Tungsten - Electron Configuration and Oxidation States - W (2024)

by Nick Connor

Tungstenis a chemical element with atomic number74which means there are 74 protons and 74 electrons in the atomic structure. Thechemical symbolfor Tungsten isW.

Electron Configuration and Oxidation States of Tungsten

Electron configuration ofTungstenis[Xe] 4f145d46s2.

Possible oxidation states are+6.

Electron Configuration

The periodic table is a tabular display of the chemical elements organized on the basis of their atomic numbers, electron configurations, and chemical properties. The electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. Knowledge of theelectron configurationof different atoms is useful in understanding the structure of the periodic table of elements.

Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms. Thechemical properties of the atomare determined by the number of protons, in fact, by number andarrangement of electrons. Theconfiguration of these electronsfollows from the principles of quantum mechanics. The number of electrons in each element’s electron shells, particularly the outermost valence shell, is the primary factor in determining its chemical bonding behavior. In the periodic table, the elements are listed in order of increasing atomic number Z.

It is thePauli exclusion principlethat requires the electrons in an atom to occupy different energy levels instead of them all condensing in the ground state. The ordering of the electrons in the ground state of multielectron atoms, starts with the lowest energy state (ground state) and moves progressively from there up the energy scale until each of the atom’s electrons has been assigned a unique set of quantum numbers. This fact has key implications for the building up of the periodic table of elements.

The first two columns on the left side of the periodic table are where thessubshells are being occupied. Because of this, the first two rows of the periodic table are labeled thes block. Similarly, thep blockare the right-most six columns of the periodic table, thed blockis the middle 10 columns of the periodic table, while thef blockis the 14-column section that is normally depicted as detached from the main body of the periodic table. It could be part of the main body, but then the periodic table would be rather long and cumbersome.

For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. The electron configuration can be visualized as the core electrons, equivalent to thenoble gasof the preceding period, and the valence electrons (e.g. [Xe] 6s2 for barium).

Oxidation States

Oxidation states are typically represented by integers which may be positive, zero, or negative. Most elements have more than one possible oxidation state. For example, carbon has nine possible integer oxidation states from −4 to +4.

The current IUPAC Gold Book definition of oxidation state is:

“Oxidation state of an atom is the charge of this atom after ionic approximation of its heteronuclear bonds…”

and the term oxidation number is nearly synonymous. An element that is not combined with any other different elements has an oxidation state of 0. Oxidation state 0 occurs for all elements – it is simply the element in its elemental form. An atom of an element in a compound will have a positive oxidation state if it has had electrons removed. Similarly, adding electrons results in a negative oxidation state. We have also distinguish between the possible and common oxidation states of every element. For example, silicon has nine possible integer oxidation states from −4 to +4, but only -4, 0 and +4 are common oxidation states.

1

H

Hydrogen

1s1

Hydrogen

Discoverer: Cavendish, Henry

Element Category: Non Metal

Hydrogenis a chemical element withatomic number1which means there are 1 protons and 1 electrons in the atomic structure. Thechemical symbolfor Hydrogen isH.

With a standard atomic weight of circa 1.008, hydrogen is the lightest element on the periodic table. Its monatomic form (H) is the most abundant chemical substance in the Universe, constituting roughly 75% of all baryonic mass.

1s1

2

He

Helium

1s2

Helium

Discoverer: Ramsey, Sir William and Cleve, Per Teodor

Element Category: Noble gas

Helium is a chemical element with atomic number 2 which means there are 2 protons and 2 electrons in the atomic structure. The chemical symbol for Helium is He.

It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas, the first in the noble gas group in the periodic table. Its boiling point is the lowest among all the elements.

1s2

3

Li

Lithium

[He] 2s1

Lithium

Discoverer: Arfvedson, Johan August

Element Category: Alkali metal

Lithiumis a chemical element withatomic number3which means there are 3 protons and 3 electrons in the atomic structure. Thechemical symbolfor Lithium isLi.

It is a soft, silvery-white alkali metal. Under standard conditions, it is the lightest metal and the lightest solid element. Like all alkali metals, lithium is highly reactive and flammable, and is stored in mineral oil.

[He] 2s1

4

Be

Beryllium

[He] 2s2

Beryllium

Discoverer: Vauquelin, Nicholas Louis

Element Category: Alkaline earth metal

Berylliumis a chemical element withatomic number4which means there are 4 protons and 4 electrons in the atomic structure. Thechemical symbolfor Beryllium isBe.

Beryllium is a hard, grayish metal naturally found in mineral rocks, coal, soil, and volcanic dust. The commercial use of beryllium requires the use of appropriate dust control equipment and industrial controls at all times because of the toxicity of inhaled beryllium-containing dusts that can cause a chronic life-threatening allergic disease in some people called berylliosis.

[He] 2s2

5

B

Boron

[He] 2s2 2p1

Boron

Discoverer: Davy, Sir H. and Thénard, L.-J. and Gay-Lussac, L.-J.

Element Category: Metalloids

Boronis a chemical element withatomic number5which means there are 5 protons and 5 electrons in the atomic structure. Thechemical symbolfor Boron isB.

Significant concentrations of boron occur on the Earth in compounds known as the borate minerals. There are over 100 different borate minerals, but the most common are: borax, kernite, ulexite etc. Natural boron consists primarily of two stable isotopes, 11B (80.1%) and 10B (19.9%). In nuclear industry boron is commonly used as a neutron absorber due to the high neutron cross-section of isotope 10B.

[He] 2s2 2p1

6

C

Carbon

[He] 2s22p2

Carbon

Discoverer: unknown

Element Category: Nonmetals

Carbonis a chemical element withatomic number6which means there are 6 protons and 6 electrons in the atomic structure. Thechemical symbolfor Carbon isC.

It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds. Carbon is one of the few elements known since antiquity. Carbon is the 15th most abundant element in the Earth’s crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen.

[He] 2s22p2

7

N

Nitrogen

[He] 2s22p3

Nitrogen

Discoverer: Rutherford, Daniel

Element Category: Nonmetals

Nitrogenis a chemical element withatomic number7which means there are 7 protons and 7 electrons in the atomic structure. Thechemical symbolfor Nitrogen isN.

Nitrogen is a colourless, odourless unreactive gas that forms about 78% of the earth’s atmosphere. Liquid nitrogen (made by distilling liquid air) boils at 77.4 kelvins (−195.8°C) and is used as a coolant.

[He] 2s22p3

8

O

Oxygen

[He] 2s22p4

Oxygen

Discoverer: Priestley, Joseph and Scheele, Carl Wilhelm

Element Category: Nonmetals

Oxygenis a chemical element withatomic number8which means there are 8 protons and 8 electrons in the atomic structure. Thechemical symbolfor Oxygen isO.

Oxygen is a colourless, odourless reactive gas, the chemical element of atomic number 8 and the life-supporting component of the air. It is a member of the chalcogen group on the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as well as with other compounds. By mass, oxygen is the third-most abundant element in the universe, after hydrogen and helium.

[He] 2s22p4

9

F

Fluorine

[He] 2s22p5

Fluorine

Discoverer: Moissan, Henri

Element Category: Nonmetals

Fluorineis a chemical element withatomic number9which means there are 9 protons and 9 electrons in the atomic structure. Thechemical symbolfor Fluorine isF.

Fluorine is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. As the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.

[He] 2s22p5

10

Ne

Neon

[He] 2s22p6

Neon

Discoverer: Ramsay, William and Travers, Morris

Element Category: Noble gas

Neonis a chemical element withatomic number10which means there are 10 protons and 10 electrons in the atomic structure. Thechemical symbolfor Neon isNe.

Neon is a colorless, odorless, inert monatomic gas under standard conditions, with about two-thirds the density of air.

[He] 2s22p6

11

Na

Sodium

[Ne] 3s1

Sodium

Discoverer: Davy, Sir Humphry

Element Category: Alkali metal

Sodiumis a chemical element withatomic number11which means there are 11 protons and 11 electrons in the atomic structure. Thechemical symbolfor Sodium isNa.

Sodium is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table, because it has a single electron in its outer shell that it readily donates, creating a positively charged atom—the Na+ cation.

[Ne] 3s1

12

Mg

Magnesium

[Ne] 3s2

Magnesium

Discoverer: Black, Joseph

Element Category: Alkaline earth metal

Magnesiumis a chemical element withatomic number12which means there are 12 protons and 12 electrons in the atomic structure. Thechemical symbolfor Magnesium isMg.

Magnesium is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (group 2, or alkaline earth metals) of the periodic table: all group 2 elements have the same electron configuration in the outer electron shell and a similar crystal structure.

[Ne] 3s2

13

Al

Aluminium

[Ne] 3s23p1

Aluminium

Discoverer: Oersted, Hans Christian

Element Category: Post-transition metals

Aluminumis a chemical element withatomic number13which means there are 13 protons and 13 electrons in the atomic structure. Thechemical symbolfor Aluminum isAl.

Aluminium is a silvery-white, soft, nonmagnetic, ductile metal in the boron group. By mass, aluminium makes up about 8% of the Earth’s crust; it is the third most abundant element after oxygen and silicon and the most abundant metal in the crust, though it is less common in the mantle below.

[Ne] 3s23p1

14

Si

Silicon

[Ne] 3s23p2

Silicon

Discoverer: Berzelius, Jöns Jacob

Element Category: Metalloids

Siliconis a chemical element withatomic number14which means there are 14 protons and 14 electrons in the atomic structure. Thechemical symbolfor Silicon isSi.

Silicon is a hard and brittle crystalline solid with a blue-grey metallic lustre, it is a tetravalent metalloid and semiconductor.

[Ne] 3s23p2

15

P

Phosphorus

[Ne] 3s23p3

Phosphorus

Discoverer: Brandt, Hennig

Element Category: Nonmetal

Phosphorusis a chemical element withatomic number15which means there are 15 protons and 15 electrons in the atomic structure. Thechemical symbolfor Phosphorus isP.

As an element, phosphorus exists in two major forms—white phosphorus and red phosphorus—but because it is highly reactive, phosphorus is never found as a free element on Earth. At 0.099%, phosphorus is the most abundant pnictogen in the Earth’s crust.

[Ne] 3s23p3

16

S

Sulfur

[Ne] 3s23p4

Sulfur

Discoverer: unknown

Element Category: Nonmetal

Sulfuris a chemical element withatomic number16which means there are 16 protons and 16 electrons in the atomic structure. Thechemical symbolfor Sulfur isS.

Sulfur is abundant, multivalent, and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S8. Elemental sulfur is a bright yellow crystalline solid at room temperature. Chemically, sulfur reacts with all elements except for gold, platinum, iridium, tellurium, and the noble gases.

[Ne] 3s23p4

17

Cl

Chlorine

[Ne] 3s23p5

Chlorine

Discoverer: Scheele, Carl Wilhelm

Element Category: Nonmetal

Chlorineis a chemical element withatomic number17which means there are 17 protons and 17 electrons in the atomic structure. Thechemical symbolfor Chlorine isCl.

Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity, behind only oxygen and fluorine.

[Ne] 3s23p5

18

Ar

Argon

[Ne] 3s23p6

Argon

Discoverer: Ramsay, Sir William and Strutt, John (Lord Rayleigh)

Element Category: Noble gas

Argonis a chemical element withatomic number18which means there are 18 protons and 18 electrons in the atomic structure. Thechemical symbolfor Argon isAr.

Argon is the third-most abundant gas in the Earth’s atmosphere, at 0.934% (9340 ppmv). Argon is mostly used as an inert shielding gas in welding and other high-temperature industrial processes where ordinarily unreactive substances become reactive; for example, an argon atmosphere is used in graphite electric furnaces to prevent the graphite from burning.

[Ne] 3s23p6

19

K

Potassium

[Ar] 4s1

Potassium

Discoverer: Davy, Sir Humphry

Element Category: Alkali metal

Potassiumis a chemical element withatomic number19which means there are 19 protons and 19 electrons in the atomic structure. Thechemical symbolfor Potassium isK.

Potassium was first isolated from potash, the ashes of plants, from which its name derives. In the periodic table, potassium is one of the alkali metals. All of the alkali metals have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge – a cation, which combines with anions to form salts. Naturally occurring potassium is composed of three isotopes, of which 40K is radioactive.

[Ar] 4s1

20

Ca

Calcium

[Ar] 4s2

Calcium

Discoverer: Davy, Sir Humphry

Element Category: Alkaline earth metal

Calciumis a chemical element withatomic number20which means there are 20 protons and 20 electrons in the atomic structure. Thechemical symbolfor Calcium isCa.

Calcium is an alkaline earth metal, it is a reactive pale yellow metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to its heavier hom*ologues strontium and barium. It is the fifth most abundant element in Earth’s crust and the third most abundant metal, after iron and aluminium.

[Ar] 4s2

21

Sc

Scandium

[Ar] 3d14s2

Scandium

Discoverer: Nilson, Lars Fredrik

Element Category: Transition metals

Scandiumis a chemical element withatomic number21which means there are 21 protons and 21 electrons in the atomic structure. Thechemical symbolfor Scandium isSc.

Scandium is a silvery-white metallic d-block element, it has historically been sometimes classified as a rare-earth element, together with yttrium and the lanthanides.

[Ar] 3d14s2

22

Ti

Titanium

[Ar] 3d24s2

Titanium

Discoverer: Gregor, William

Element Category: Transition metals

Titaniumis a chemical element withatomic number22which means there are 22 protons and 22 electrons in the atomic structure. Thechemical symbolfor Titanium isTi. Titanium is a lustrous transition metal with a silver color, low density, and high strength. Titanium is resistant to corrosion in sea water, aqua regia, and chlorine. Titanium can be used in surface condensers. These condensers use tubes that are usually made of stainless steel, copper alloys, or titanium depending on several selection criteria (such as thermal conductivity or corrosion resistance). Titanium condenser tubes are usually the best technical choice, however titanium is very expensive material.

[Ar] 3d24s2

23

V

Vanadium

[Ar] 3d34s2

Vanadium

Discoverer: Del Rio, Andrés Manuel (1801) and Sefström, Nils Gabriel (1830)

Element Category: Transition metals

Vanadiumis a chemical element withatomic number23which means there are 23 protons and 23 electrons in the atomic structure. Thechemical symbolfor Vanadium isV.

Vanadium is a hard, silvery grey, ductile, and malleable transition metal. The elemental metal is rarely found in nature, but once isolated artificially, the formation of an oxide layer (passivation) stabilizes the free metal somewhat against further oxidation.

[Ar] 3d34s2

24

Cr

Chromium

[Ar] 3d54s1

Chromium

Discoverer: Vauquelin

Element Category: Transition metals

Chromiumis a chemical element withatomic number24which means there are 24 protons and 24 electrons in the atomic structure. Thechemical symbolfor Chromium isCr.

Chromium is a steely-grey, lustrous, hard and brittle metal4 which takes a high polish, resists tarnishing, and has a high melting point. A major development was the discovery that steel could be made highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel.

[Ar] 3d54s1

25

Mn

Manganese

[Ar] 3d5 4s2

Manganese

Discoverer: Gahn, Johan Gottlieb

Element Category: Transition metals

Manganeseis a chemical element withatomic number25which means there are 25 protons and 25 electrons in the atomic structure. Thechemical symbolfor Manganese isMn.

Manganese is a metal with important industrial metal alloy uses, particularly in stainless steels.

[Ar] 3d5 4s2

26

Fe

Iron

[Ar] 3d6 4s2

Iron

Discoverer: unknown

Element Category: Transition metals

Ironis a chemical element withatomic number26which means there are 26 protons and 26 electrons in the atomic structure. Thechemical symbolfor Iron isFe.

Iron is a metal in the first transition series. It is by mass the most common element on Earth, forming much of Earth’s outer and inner core. It is the fourth most common element in the Earth’s crust. Its abundance in rocky planets like Earth is due to its abundant production by fusion in high-mass stars.

[Ar] 3d6 4s2

27

Co

Cobalt

[Ar] 3d7 4s2

Cobalt

Discoverer: Brandt, Georg

Element Category: Transition metals

Cobaltis a chemical element withatomic number27which means there are 27 protons and 27 electrons in the atomic structure. Thechemical symbolfor Cobalt isCo.

Cobalt is found in the Earth’s crust only in chemically combined form, save for small deposits found in alloys of natural meteoric iron. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal.

[Ar] 3d7 4s2

28

Ni

Nickel

[Ar] 3d8 4s2

Nickel

Discoverer: Cronstedt, Alex Fredrik

Element Category: Transition metals

Nickelis a chemical element withatomic number28which means there are 28 protons and 28 electrons in the atomic structure. Thechemical symbolfor Nickel isNi.

Nickel is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile.

[Ar] 3d8 4s2

29

Cu

Copper

[Ar] 3d10 4s1

Copperis a chemical element withatomic number29which means there are 29 protons and 29 electrons in the atomic structure. Thechemical symbolfor Copper isCu.

Copper is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a reddish-orange color. Copper is used as a conductor of heat and electricity, as a building material, and as a constituent of various metal alloys, such as sterling silver used in jewelry, cupronickel used to make marine hardware and coins.

[Ar] 3d10 4s1

30

Zn

Zinc

[Ar] 3d104s2

Zinc

Discoverer: unknown

Element Category: Transition metals

Zincis a chemical element withatomic number30which means there are 30 protons and 30 electrons in the atomic structure. Thechemical symbolfor Zinc isZn.

In some respects zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size.

[Ar] 3d104s2

31

Ga

Gallium

[Ar] 3d104s24p1

Gallium

Discoverer: Lecoq de Boisbaudran, Paul-Émile

Element Category: Post-transition metals

Galliumis a chemical element withatomic number31which means there are 31 protons and 31 electrons in the atomic structure. Thechemical symbolfor Gallium isGa.

Gallium has similarities to the other metals of the group, aluminium, indium, and thallium. Gallium does not occur as a free element in nature, but as gallium(III) compounds in trace amounts in zinc ores and in bauxite.

[Ar] 3d104s24p1

32

Ge

Germanium

[Ar] 3d104s24p2

Germanium

Discoverer: Winkler, Clemens A.

Element Category: Metalloids

Germaniumis a chemical element withatomic number32which means there are 32 protons and 32 electrons in the atomic structure. Thechemical symbolfor Germanium isGe.

Germanium is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. Pure germanium is a semiconductor with an appearance similar to elemental silicon.

[Ar] 3d104s24p2

33

As

Arsenic

[Ar] 3d104s24p3

Arsenic

Discoverer: unknown

Element Category: Metalloids

Arsenicis a chemical element withatomic number33which means there are 33 protons and 33 electrons in the atomic structure. Thechemical symbolfor Arsenic isAs.

Arsenic occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal. Arsenic is a metalloid.

[Ar] 3d104s24p3

34

Se

Selenium

[Ar] 3d104s24p4

Selenium

Discoverer: Berzelius, Jöns Jacob

Element Category: Nonmetal

Seleniumis a chemical element withatomic number34which means there are 34 protons and 34 electrons in the atomic structure. Thechemical symbolfor Selenium isSe.

Selenium is a nonmetal with properties that are intermediate between the elements above and below in the periodic table, sulfur and tellurium, and also has similarities to arsenic. It rarely occurs in its elemental state or as pure ore compounds in the Earth’s crust.

[Ar] 3d104s24p4

35

Br

Bromine

[Ar] 3d104s24p5

Bromine

Discoverer: Balard, Antoine-Jérôme

Element Category: Nonmetal

Bromineis a chemical element withatomic number35which means there are 35 protons and 35 electrons in the atomic structure. Thechemical symbolfor Bromine isBr.

Bromine is the third-lightest halogen, and is a fuming red-brown liquid at room temperature that evaporates readily to form a similarly coloured gas. Its properties are thus intermediate between those of chlorine and iodine.

[Ar] 3d104s24p5

36

Kr

Krypton

[Ar] 3d104s24p6

Krypton

Discoverer: Ramsay, Sir William and Travers, Morris

Element Category: Noble gas

Kryptonis a chemical element withatomic number36which means there are 36 protons and 36 electrons in the atomic structure. Thechemical symbolfor Krypton isKr.

Krypton is a member of group 18 (noble gases) elements. A colorless, odorless, tasteless noble gas, krypton occurs in trace amounts in the atmosphere and is often used with other rare gases in fluorescent lamps.

[Ar] 3d104s24p6

37

Rb

Rubidium

[Kr] 5s1

Rubidium

Discoverer: Bunsen, Robert Wilhelm and Kirchhoff, Gustav Robert

Element Category: Alkali metals

Rubidiumis a chemical element withatomic number37which means there are 37 protons and 37 electrons in the atomic structure. Thechemical symbolfor Rubidium isRb.

Rubidium is a soft, silvery-white metallic element of the alkali metal group, with an atomic mass of 85.4678. Elemental rubidium is highly reactive, with properties similar to those of other alkali metals, including rapid oxidation in air.

[Kr] 5s1

38

Sr

Strontium

[Kr] 5s2

Strontium

Discoverer: Crawford, Adair

Element Category: Alkaline earth metals

Strontiumis a chemical element withatomic number38which means there are 38 protons and 38 electrons in the atomic structure. Thechemical symbolfor Strontium isSr.

Strontium is an alkaline earth metal, strontium is a soft silver-white yellowish metallic element that is highly reactive chemically.

[Kr] 5s2

39

Y

Yttrium

[Kr] 4d15s2

Yttrium

Discoverer: Gadolin, Johan

Element Category: Transition metals

Yttriumis a chemical element withatomic number39which means there are 39 protons and 39 electrons in the atomic structure. Thechemical symbolfor Yttrium isY.

Yttrium is a silvery-metallic transition metal chemically similar to the lanthanides and has often been classified as a “rare-earth element”.

[Kr] 4d15s2

40

Zr

Zirconium

[Kr] 4d25s2

Zirconium

Discoverer: Klaproth, Martin Heinrich

Element Category: Transition metals

Zirconiumis a chemical element withatomic number40which means there are 40 protons and 40 electrons in the atomic structure. Thechemical symbolfor Zirconium isZr. Zirconium is a lustrous, grey-white, strong transition metal that resembles hafnium and, to a lesser extent, titanium. Zirconium is mainly used as a refractory and opacifier, although small amounts are used as an alloying agent for its strong resistance to corrosion. Zirconium is widely used as a cladding for nuclear reactor fuels.

[Kr] 4d25s2

41

Nb

Niobium

[Kr] 4d45s1

Niobium

Discoverer: Hatchet, Charles

Element Category: Transition metals

Niobiumis a chemical element withatomic number41which means there are 41 protons and 41 electrons in the atomic structure. Thechemical symbolfor Niobium isNb.

Niobium is a soft, grey, ductile transition metal, often found in the minerals pyrochlore (the main commercial source for niobium) and columbite.

[Kr] 4d45s1

42

Mo

Molybdenum

[Kr] 4d5 5s1

Molybdenum

Discoverer: Scheele, Carl Welhelm

Element Category: Transition metals

Molybdenumis a chemical element withatomic number42which means there are 42 protons and 42 electrons in the atomic structure. Thechemical symbolfor Molybdenum isMo.

Molybdenum a silvery metal with a gray cast, has the sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of world production of the element (about 80%) is used in steel alloys, including high-strength alloys and superalloys.

[Kr] 4d5 5s1

43

Tc

Technetium

[Kr] 4d5 5s2

Technetium

Discoverer: Perrier, Carlo and Segrè, Emilio

Element Category: Transition metals

Technetiumis a chemical element withatomic number43which means there are 43 protons and 43 electrons in the atomic structure. Thechemical symbolfor Technetium isTc.

Technetium is the lightest element whose isotopes are all radioactive; none are stable. Nearly all technetium is produced synthetically, and only minute amounts are found in the Earth’s crust. The chemical properties of this silvery gray, crystalline transition metal are intermediate between rhenium and manganese.

[Kr] 4d5 5s2

44

Ru

Ruthenium

[Kr] 4d7 5s1

Ruthenium

Discoverer: Klaus, Karl Karlovich

Element Category: Transition metals

Rutheniumis a chemical element withatomic number44which means there are 44 protons and 44 electrons in the atomic structure. Thechemical symbolfor Ruthenium isRu.

Ruthenium is a rare transition metal belonging to the platinum group of the periodic table. Like the other metals of the platinum group, ruthenium is inert to most other chemicals.

[Kr] 4d7 5s1

45

Rh

Rhodium

[Kr] 4d8 5s1

Rhodium

Discoverer: Wollaston, William Hyde

Element Category: Transition metals

Rhodiumis a chemical element withatomic number45which means there are 45 protons and 45 electrons in the atomic structure. Thechemical symbolfor Rhodium isRh.

Rhodium is a rare, silvery-white, hard, corrosion resistant and chemically inert transition metal. It is a noble metal and a member of the platinum group.

[Kr] 4d8 5s1

46

Pd

Palladium

[Kr] 4d10

Palladium

Discoverer: Wollaston, William Hyde

Element Category: Transition metals

Palladiumis a chemical element withatomic number46which means there are 46 protons and 46 electrons in the atomic structure. Thechemical symbolfor Palladium isPd.

Palladium, platinum, rhodium, ruthenium, iridium and osmium form a group of elements referred to as the platinum group metals (PGMs). These have similar chemical properties, but palladium has the lowest melting point and is the least dense of them.

[Kr] 4d10

47

Ag

Silver

[Kr] 4d105s1

Silver

Discoverer: unknown

Element Category: Transition metals

Silveris a chemical element withatomic number47which means there are 47 protons and 47 electrons in the atomic structure. Thechemical symbolfor Silver isAg.

Silver is a soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earth’s crust in the pure, free elemental form (“native silver”), as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite.

[Kr] 4d105s1

48

Cd

Cadmium

[Kr] 4d105s2

Cadmium

Discoverer: Stromeyer, Prof. Friedrich

Element Category: Transition metals

Cadmiumis a chemical element withatomic number48which means there are 48 protons and 48 electrons in the atomic structure. Thechemical symbolfor Cadmium isCd.

Cadmium is a soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. In nuclear industry cadmium is commonly used as a thermal neutron absorber due to very high neutron absorption cross-section of 113Cd. 113Cd has specific absorption cross-section.

[Kr] 4d105s2

49

In

Indium

[Kr] 4d105s25p1

Indium

Discoverer: Reich, Ferdinand and Richter, Hieronymus

Element Category: Post-transition metals

Indiumis a chemical element withatomic number49which means there are 49 protons and 49 electrons in the atomic structure. Thechemical symbolfor Indium isIn.

Indium is a post-transition metal that makes up 0.21 parts per million of the Earth’s crust. Very soft and malleable, indium has a melting point higher than sodium and gallium, but lower than lithium and tin. Chemically, indium is similar to gallium and thallium.

[Kr] 4d105s25p1

50

Sn

Tin

[Kr] 4d105s25p2

Tin

Discoverer: unknown

Element Category: Post-transition metals

Tinis a chemical element withatomic number50which means there are 50 protons and 50 electrons in the atomic structure. Thechemical symbolfor Tin isSn.

Tin is a post-transition metal in group 14 of the periodic table. It is obtained chiefly from the mineral cassiterite, which contains tin dioxide. The first alloy used on a large scale was bronze, made of tin and copper, from as early as 3000 BC.

[Kr] 4d105s25p2

51

Sb

Antimony

[Kr] 4d105s25p3

Antimony

Discoverer: unknown

Element Category: Metalloids

Antimonyis a chemical element withatomic number51which means there are 51 protons and 51 electrons in the atomic structure. Thechemical symbolfor Antimony isSb.

Antimony is a lustrous gray metalloid, it is found in nature mainly as the sulfide mineral stibnite. Antimony compounds have been known since ancient times and were powdered for use as medicine and cosmetics, often known by the Arabic name, kohl.

[Kr] 4d105s25p3

52

Te

Tellurium

[Kr] 4d105s25p4

Tellurium

Discoverer: Müller von Reichenstein, Franz Joseph

Element Category: Metalloids

Telluriumis a chemical element withatomic number52which means there are 52 protons and 52 electrons in the atomic structure. Thechemical symbolfor Tellurium isTe.

Tellurium is a brittle, mildly toxic, rare, silver-white metalloid. Tellurium is chemically related to selenium and sulfur. It is occasionally found in native form as elemental crystals. Tellurium is far more common in the universe as a whole than on Earth. Its extreme rarity in the Earth’s crust, comparable to that of platinum.

[Kr] 4d105s25p4

53

I

Iodine

[Kr] 4d105s25p5

Iodine

Discoverer: Courtois, Bernard

Element Category: Nonmetal

Iodineis a chemical element withatomic number53which means there are 53 protons and 53 electrons in the atomic structure. Thechemical symbolfor Iodine isI.

Iodine is the heaviest of the stable halogens, it exists as a lustrous, purple-black metallic solid at standard conditions that sublimes readily to form a violet gas. Iodine is the least abundant of the stable halogens, being the sixty-first most abundant element. It is even less abundant than the so-called rare earths. It is the heaviest essential mineral nutrient.

[Kr] 4d105s25p5

54

Xe

Xenon

[Kr] 4d105s25p6

Xenon

Discoverer: Ramsay, William and Travers, Morris William

Element Category: Noble gas

Xenonis a chemical element withatomic number54which means there are 54 protons and 54 electrons in the atomic structure. Thechemical symbolfor Xenon isXe.

Xenon is a colorless, dense, odorless noble gas found in the Earth’s atmosphere in trace amounts. The name xenon for this gas comes from the Greek word ξένον [xenon], neuter singular form of ξένος [xenos], meaning ‘foreign(er)’, ‘strange(r)’, or ‘guest’. In nuclear industry, especially artificial xenon 135 has a tremendous impact on the operation of a nuclear reactor.

[Kr] 4d105s25p6

55

Cs

Caesium

[Xe] 6s1

Caesium

Discoverer: Kirchhoff, Gustav and Bunsen, Robert

Element Category: Alkali metal

Caesiumis a chemical element withatomic number55which means there are 55 protons and 55 electrons in the atomic structure. Thechemical symbolfor Caesium isCs.

Caesium is a soft, silvery-gold alkali metal with a melting point of 28.5 °C, which makes it one of only five elemental metals that are liquid at or near room temperature. Caesium has physical and chemical properties similar to those of rubidium and potassium.

[Xe] 6s1

56

Ba

Barium

[Xe] 6s2

Barium

Discoverer: Davy, Sir Humphry

Element Category: Alkaline earth metals

Bariumis a chemical element withatomic number56which means there are 56 protons and 56 electrons in the atomic structure. Thechemical symbolfor Barium isBa.

Barium is the fifth element in group 2 and is a soft, silvery alkaline earth metal. Because of its high chemical reactivity, barium is never found in nature as a free element. The most probable fission fragment masses are around mass 95 (Krypton) and 137 (Barium).

[Xe] 6s2

57-71

Lanthanoids

Lanthanoids

Discoverer: —

Element Category:

Lanthanoids comprise the 15 metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium. These elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements.

72

Hf

Hafnium

[Xe] 4f145d26s2

Hafnium

Discoverer: Coster, Dirk and De Hevesy, George Charles

Element Category: Transition metals

Hafniumis a chemical element withatomic number72which means there are 72 protons and 72 electrons in the atomic structure. Thechemical symbolfor Hafnium isHf. Hafnium is a lustrous, silvery gray, tetravalent transition metal, hafnium chemically resembles zirconium and is found in many zirconium minerals. Hafnium’s large neutron capture cross-section makes it a good material for neutron absorption in control rods in nuclear power plants, but at the same time requires that it be removed from the neutron-transparent corrosion-resistant zirconium alloys used in nuclear reactors.

[Xe] 4f145d26s2

73

Ta

Tantalum

[Xe] 4f145d36s2

Tantalum

Discoverer: Ekeberg, Anders Gustav

Element Category: Transition metals

Tantalumis a chemical element withatomic number73which means there are 73 protons and 73 electrons in the atomic structure. Thechemical symbolfor Tantalum isTa.

Tantalum is a rare, hard, blue-gray, lustrous transition metal that is highly corrosion-resistant.

[Xe] 4f145d36s2

74

W

Tungsten

[Xe] 4f145d46s2

Tungsten

Discoverer: Elhuyar, Juan José and Elhuyar, Fausto

Element Category: Transition metals

Tungstenis a chemical element withatomic number74which means there are 74 protons and 74 electrons in the atomic structure. Thechemical symbolfor Tungsten isW.

Tungsten is a rare metal found naturally on Earth almost exclusively in chemical compounds. Tungsten is an intrinsically brittle and hard material, making it difficult to work.

[Xe] 4f145d46s2

75

Re

Rhenium

[Xe] 4f145d56s2

Rhenium

Discoverer: Noddack, Walter and Berg, Otto Carl and Tacke, Ida

Element Category: Transition metals

Rheniumis a chemical element withatomic number75which means there are 75 protons and 75 electrons in the atomic structure. Thechemical symbolfor Rhenium isRe.

Rhenium is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table.

[Xe] 4f145d56s2

76

Os

Osmium

[Xe] 4f145d66s2

Osmium

Discoverer: Tennant, Smithson

Element Category: Transition metals

Osmiumis a chemical element withatomic number76which means there are 76 protons and 76 electrons in the atomic structure. Thechemical symbolfor Osmium isOs. Osmium is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mostly in platinum ores. Osmium is the densest naturally occurring element, with a density of 22.59 g/cm3. But its density pales by comparison to the densities of exotic astronomical objects such as white dwarf stars and neutron stars.

[Xe] 4f145d66s2

77

Ir

Iridium

[Xe] 4f145d76s2

Iridium

Discoverer: Tennant, Smithson

Element Category: Transition metals

Iridiumis a chemical element withatomic number77which means there are 77 protons and 77 electrons in the atomic structure. Thechemical symbolfor Iridium isIr.

Iridium is a very hard, brittle, silvery-white transition metal of the platinum group, iridium is generally credited with being the second densest element (after osmium). It is also the most corrosion-resistant metal, even at temperatures as high as 2000 °C.

[Xe] 4f145d76s2

78

Pt

Platinum

[Xe] 4f145d96s1

Platinum

Discoverer: Ulloa, Antonio de

Element Category: Transition metals

Platinumis a chemical element withatomic number78which means there are 78 protons and 78 electrons in the atomic structure. Thechemical symbolfor Platinum isPt. Platinum is a dense, malleable, ductile, highly unreactive, precious, silverish-white transition metal. Platinum is one of the least reactive metals. It has remarkable resistance to corrosion, even at high temperatures, and is therefore considered a noble metal. Platinum is used in catalytic converters, laboratory equipment, electrical contacts and electrodes, platinum resistance thermometers, dentistry equipment, and jewelry.

[Xe] 4f145d96s1

79

Au

Gold

[Xe] 4f145d106s1

Gold

Discoverer: unknown

Element Category: Transition metals

Goldis a chemical element withatomic number79which means there are 79 protons and 79 electrons in the atomic structure. Thechemical symbolfor Gold isAu.

Gold is a bright, slightly reddish yellow, dense, soft, malleable, and ductile metal. Gold is a transition metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions. Gold is thought to have been produced in supernova nucleosynthesis, from the collision of neutron stars.

[Xe] 4f145d106s1

80

Hg

Mercury

[Xe] 4f14 5d10 6s2

Mercury

Discoverer: unknown

Element Category: Transition metals

Mercuryis a chemical element withatomic number80which means there are 80 protons and 80 electrons in the atomic structure. Thechemical symbolfor Mercury isHg.

Mercury is commonly known as quicksilver and was formerly named hydrargyrum. Mercury is a heavy, silvery d-block element, mercury is the only metallic element that is liquid at standard conditions for temperature and pressure.

[Xe] 4f14 5d10 6s2

81

Tl

Thallium

[Hg] 6p1

Thallium

Discoverer: Crookes, William

Element Category: Post-transition metals

Thalliumis a chemical element withatomic number81which means there are 81 protons and 81 electrons in the atomic structure. Thechemical symbolfor Thallium isTl.

Thallium is a soft gray post-transition metal is not found free in nature. Commercially, thallium is produced as a byproduct from refining of heavy metal sulfide ores. Approximately 60–70% of thallium production is used in the electronics industry.

[Hg] 6p1

82

Pb

Lead

[Hg] 6p2

Lead

Discoverer: unknown

Element Category: Post-transition metals

Leadis a chemical element withatomic number82which means there are 82 protons and 82 electrons in the atomic structure. Thechemical symbolfor Lead isPb.

Lead is a heavy metal that is denser than most common materials. Lead is soft and malleable, and has a relatively low melting point. Lead is widely used as a gamma shield. Major advantage of lead shield is in its compactness due to its higher density. Lead has the highest atomic number of any stable element and concludes three major decay chains of heavier elements.

[Hg] 6p2

83

Bi

Bismuth

[Hg] 6p3

Bismuth

Discoverer: Geoffroy, Claude

Element Category: Post-transition metals

Bismuthis a chemical element withatomic number83which means there are 83 protons and 83 electrons in the atomic structure. Thechemical symbolfor Bismuth isBi.

Bismuth is a brittle metal with a silvery white color when freshly produced, but surface oxidation can give it a pink tinge. Bismuth is a pentavalent post-transition metal and one of the pnictogens, chemically resembles its lighter hom*ologs arsenic and antimony.

[Hg] 6p3

84

Po

Polonium

[Hg] 6p4

Polonium

Discoverer: Curie, Marie and Pierre

Element Category: Post-transition metals

Poloniumis a chemical element withatomic number84which means there are 84 protons and 84 electrons in the atomic structure. Thechemical symbolfor Polonium isPo.

Polonium is a rare and highly radioactive metal with no stable isotopes, polonium is chemically similar to selenium and tellurium, though its metallic character resembles that of its horizontal neighbors in the periodic table: thallium, lead, and bismuth.

[Hg] 6p4

85

At

Astatine

[Hg] 6p5

Astatine

Discoverer: Corson, Dale R. and Mackenzie, K. R.

Element Category: Metalloids

Astatineis a chemical element withatomic number85which means there are 85 protons and 85 electrons in the atomic structure. Thechemical symbolfor Astatine isAt.

Astatine is the rarest naturally occurring element on the Earth’s crust. It occurs on Earth as the decay product of various heavier elements. The bulk properties of astatine are not known with any certainty.

[Hg] 6p5

86

Rn

Radon

[Hg] 6p6

Radon

Discoverer: Dorn, Friedrich Ernst

Element Category: Noble gas

Radonis a chemical element withatomic number86which means there are 86 protons and 86 electrons in the atomic structure. Thechemical symbolfor Radon isRn.

Radon is a radioactive, colorless, odorless, tasteless noble gas. Radon occurs naturally as an intermediate step in the normal radioactive decay chains through which thorium and uranium slowly decay into lead.

[Hg] 6p6

87

Fr

Francium

[Rn] 7s1

Francium

Discoverer: Perey, Marguerite

Element Category: Alkali metal

Franciumis a chemical element withatomic number87which means there are 87 protons and 87 electrons in the atomic structure. Thechemical symbolfor Francium isFr.

Francium is an alkali metal, that has one valence electron. Francium is the second-least electronegative element, behind only caesium, and is the second rarest naturally occurring element (after astatine). Francium is a highly radioactive metal that decays into astatine, radium, and radon.

[Rn] 7s1

88

Ra

Radium

[Rn] 7s2

Radium

Discoverer: Curie, Marie and Pierre

Element Category: Alkaline earth metal

Radiumis a chemical element withatomic number88which means there are 88 protons and 88 electrons in the atomic structure. Thechemical symbolfor Radium isRa.

Pure radium is silvery-white alkaline earth metal. All isotopes of radium are highly radioactive, with the most stable isotope being radium-226.

[Rn] 7s2

89-103

Actinoids

Actinoids

Discoverer: —

Element Category:

The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to 103, actinium through lawrencium.

104

Rf

Rutherfordium

[Rn] 5f146d2 7s2

Rutherfordium

Discoverer: Scientists at Dubna, Russia (1964)/Albert Ghiorso et. al. (1969)

Element Category: Transition metal

Rutherfordiumis a chemical element withatomic number104which means there are 104 protons and 104 electrons in the atomic structure. Thechemical symbolfor Rutherfordium isRf.

[Rn] 5f146d2 7s2

105

Db

Dubnium

[Rn] 5f146d3 7s2

Dubnium

Discoverer: Scientists at Dubna, Russia (1967)/Lawrence Berkeley Laboratory (1970)

Element Category: Transition metal

Dubniumis a chemical element withatomic number105which means there are 105 protons and 105 electrons in the atomic structure. Thechemical symbolfor Dubnium isDb.

[Rn] 5f146d3 7s2

106

Sg

Seaborgium

[Rn] 5f146d4 7s2

Seaborgium

Discoverer: Albert Ghiorso et. al.

Element Category: Transition metal

Seaborgiumis a chemical element withatomic number106which means there are 106 protons and 106 electrons in the atomic structure. Thechemical symbolfor Seaborgium isSg.

[Rn] 5f146d4 7s2

107

Bh

Bohrium

[Rn] 5f146d5 7s2

Bohrium

Discoverer: Scientists at Dubna, Russia

Element Category: Transition metal

Bohriumis a chemical element withatomic number107which means there are 107 protons and 107 electrons in the atomic structure. Thechemical symbolfor Bohrium isBh.

[Rn] 5f146d5 7s2

108

Hs

Hassium

[Rn] 5f146d6 7s2

Hassium

Discoverer: Armbruster, Paula and Muenzenberg, Dr. Gottfried

Element Category: Transition metal

Hassiumis a chemical element withatomic number108which means there are 108 protons and 108 electrons in the atomic structure. Thechemical symbolfor Hassium isHs. It is a synthetic element (first synthesised at Hasse in Germany) and radioactive. The most stable known isotope,269Hs, has a half-life of approximately 9.7 seconds. It has an estimated density of 40.7 x 103kg/m3. The density of Hassium results from itshigh atomic weightand from the significant decrease inionic radiiof the elements in the lanthanide series, known aslanthanide and actinide contraction.

[Rn] 5f146d6 7s2

109

Mt

Meitnerium

[Rn] 5f146d7 7s2

Meitnerium

Discoverer: Armbruster, Paula and Muenzenberg, Dr. Gottfried

Element Category: unknown, probably a transition metal

Meitneriumis a chemical element withatomic number109which means there are 109 protons and 109 electrons in the atomic structure. Thechemical symbolfor Meitnerium isMt.

[Rn] 5f146d7 7s2

110

Ds

Darmstadtium

[Rn] 5f146d8 7s2

Darmstadtium

Discoverer: Armbruster, Paula and Muenzenberg, Dr. Gottfried

Element Category: unknown, probably a transition metal

Darmstadtiumis a chemical element withatomic number110which means there are 110 protons and 110 electrons in the atomic structure. Thechemical symbolfor Darmstadtium isDs.

[Rn] 5f146d8 7s2

111

Rg

Roentgenium

[Rn] 5f146d9 7s2

Roentgenium

Discoverer: David Anderson, Ruhani Rabin, Team Updraft

Element Category: unknown, probably a transition metal

Roentgeniumis a chemical element withatomic number111which means there are 111 protons and 111 electrons in the atomic structure. Thechemical symbolfor Roentgenium isRg.

[Rn] 5f146d9 7s2

112

Cn

Copernicium

[Rn] 5f146d10 7s2

Copernicium

Discoverer: Armbruster, Paula and Muenzenberg, Dr. Gottfried

Element Category: unknown, probably a transition metal

Coperniciumis a chemical element withatomic number112which means there are 112 protons and 112 electrons in the atomic structure. Thechemical symbolfor Copernicium isCn.

[Rn] 5f146d10 7s2

113

Nh

Nihonium

[Rn] 5f146d10 7s2 7p1

Nihonium

Discoverer: Y. T. Oganessian et. al.

Element Category: unknown, probably a transition metal

Nihoniumis a chemical element withatomic number113which means there are 113 protons and 113 electrons in the atomic structure. Thechemical symbolfor Nihonium isNh.

[Rn] 5f146d10 7s2 7p1

114

Fl

Flerovium

[Rn] 5f146d10 7s2 7p2

Flerovium

Discoverer: Scientists at Dubna, Russia

Element Category: unknown, probably a post-transition metal

Fleroviumis a chemical element withatomic number114which means there are 114 protons and 114 electrons in the atomic structure. Thechemical symbolfor Flerovium isFl.

[Rn] 5f146d10 7s2 7p2

115

Mc

Moscovium

[Rn] 5f146d10 7s2 7p3

Moscovium

Discoverer: Y. T. Oganessian et. al.

Element Category: unknown

Moscoviumis a chemical element withatomic number115which means there are 115 protons and 115 electrons in the atomic structure. Thechemical symbolfor Moscovium isMc.

[Rn] 5f146d10 7s2 7p3

116

Lv

Livermorium

[Rn] 5f146d10 7s2 7p4

Livermorium

Discoverer: Scientists at Dubna, Russia

Element Category: unknown

Livermoriumis a chemical element withatomic number116which means there are 116 protons and 116 electrons in the atomic structure. Thechemical symbolfor Livermorium isLv.

[Rn] 5f146d10 7s2 7p4

117

Ts

Tennessine

[Rn] 5f146d10 7s2 7p5

Tennessine

Discoverer: —

Element Category: unknown

Tennessineis a chemical element withatomic number117which means there are 117 protons and 117 electrons in the atomic structure. Thechemical symbolfor Tennessine isTs.

[Rn] 5f146d10 7s2 7p5

118

Og

Oganesson

[Rn] 5f146d10 7s2 7p6

Oganesson

Discoverer: Y. T. Oganessian et. al.

Element Category: unknown

Oganessonis a chemical element withatomic number118which means there are 118 protons and 118 electrons in the atomic structure. Thechemical symbolfor Oganesson isOg.

[Rn] 5f146d10 7s2 7p6

57

La

Lanthanum

[Xe] 5d16s2

Lanthanum

Discoverer: Mosander, Carl Gustav

Element Category: Lanthanoids

Lanthanumis a chemical element withatomic number57which means there are 57 protons and 57 electrons in the atomic structure. Thechemical symbolfor Lanthanum isLa.

Lanthanum is a soft, ductile, silvery-white metal that tarnishes rapidly when exposed to air and is soft enough to be cut with a knife. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype. It is also sometimes considered the first element of the 6th-period transition metals and is traditionally counted among the rare earth elements.

[Xe] 5d16s2

58

Ce

Cerium

[Xe] 4f15d16s2

Cerium

Discoverer: Hisinger, Wilhelm and Berzelius, Jöns Jacob/Klaproth, Martin Heinrich

Element Category: Lanthanoids

Ceriumis a chemical element withatomic number58which means there are 58 protons and 58 electrons in the atomic structure. Thechemical symbolfor Cerium isCe.

Cerium is a soft, ductile and silvery-white metal that tarnishes when exposed to air, and it is soft enough to be cut with a knife. Cerium is the second element in the lanthanide series. Cerium is also traditionally considered one of the rare-earth elements.

[Xe] 4f15d16s2

59

Pr

Praseodymium

[Xe] 4f36s2

Praseodymium

Discoverer: Von Welsbach, Baron Auer

Element Category: Lanthanoids

Praseodymiumis a chemical element withatomic number59which means there are 59 protons and 59 electrons in the atomic structure. Thechemical symbolfor Praseodymium isPr.

Praseodymium is a soft, silvery, malleable and ductile metal, valued for its magnetic, electrical, chemical, and optical properties. Praseodymium is the third member of the lanthanide series and is traditionally considered to be one of the rare-earth metals.

[Xe] 4f36s2

60

Nd

Neodymium

[Xe] 4f46s2

Neodymium

Discoverer: Von Welsbach, Baron Auer

Element Category: Lanthanoids

Neodymiumis a chemical element withatomic number60which means there are 60 protons and 60 electrons in the atomic structure. Thechemical symbolfor Neodymium isNd.

Neodymium is a soft silvery metal that tarnishes in air. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Although neodymium is classed as a rare earth, it is a fairly common element.

[Xe] 4f46s2

61

Pm

Promethium

[Xe] 4f56s2

Promethium

Discoverer: Marinsky, Jacob A. and Coryell, Charles D. and Glendenin, Lawerence. E.

Element Category: Lanthanoids

Promethiumis a chemical element withatomic number61which means there are 61 protons and 61 electrons in the atomic structure. Thechemical symbolfor Promethium isPm.

Promethium is one of only two such elements that are followed in the periodic table by elements with stable forms. All of its isotopes are radioactive. In nuclear reactors, promethium equilibrium exists in power operation. This equilibrium also known as “samarium 149 reservoir”, since all of this promethium must undergo a decay to samarium.

[Xe] 4f56s2

62

Sm

Samarium

[Xe] 4f66s2

Samarium

Discoverer: Lecoq de Boisbaudran, Paul-Émile

Element Category: Lanthanoids

Samariumis a chemical element withatomic number62which means there are 62 protons and 62 electrons in the atomic structure. Thechemical symbolfor Samarium isSm. Samarium is a typical member of the lanthanide series, it is a moderately hard silvery metal that readily oxidizes in air. The name samarium is after the mineral samarskite from which it was isolated. Although classified as a rare earth element, samarium is the 40th most abundant element in the Earth’s crust and is more common than such metals as tin. In nuclear industry, especially natural and artificial samarium 149 has an important impact on the operation of a nuclear reactor.

[Xe] 4f66s2

63

Eu

Europium

[Xe] 4f76s2

Europium

Discoverer: Demarçay, Eugène-Antole

Element Category: Lanthanoids

Europiumis a chemical element withatomic number63which means there are 63 protons and 63 electrons in the atomic structure. Thechemical symbolfor Europium isEu.

Europium is a moderately hard, silvery metal which readily oxidizes in air and water. Being a typical member of the lanthanide series, europium usually assumes the oxidation state +3. Europium is one of the least abundant elements in the universe. Only about 5×10−8% of all matter in the universe is europium.

[Xe] 4f76s2

64

Gd

Gadolinium

[Xe] 4f75d16s2

Gadolinium

Discoverer: De Marignac, Charles Galissard

Element Category: Lanthanoids

Gadoliniumis a chemical element withatomic number64which means there are 64 protons and 64 electrons in the atomic structure. Thechemical symbolfor Gadolinium isGd.

Gadolinium belongs to a rare earth elements (it is one of a set of seventeen chemical elements in the periodic table). In nuclear industry gadolinium is commonly used as a neutron absorber due to very high neutron absorbtion cross-section of two isotopes 155Gd and 157Gd. In fact their absorption cross-sections are the highest among all stable isotopes.

[Xe] 4f75d16s2

65

Tb

Terbium

[Xe] 4f96s2

Terbium

Discoverer: Mosander, Carl Gustav

Element Category: Lanthanoids

Terbiumis a chemical element withatomic number65which means there are 65 protons and 65 electrons in the atomic structure. Thechemical symbolfor Terbium isTb.

Terbium is a silvery-white, rare earth metal that is malleable, ductile, and soft enough to be cut with a knife. The ninth member of the lanthanide series, terbium is a fairly electropositive metal that reacts with water, evolving hydrogen gas.

[Xe] 4f96s2

66

Dy

Dysprosium

[Xe] 4f106s2

Dysprosium

Discoverer: Lecoq de Boisbaudran, Paul-Émile

Element Category: Lanthanoids

Dysprosiumis a chemical element withatomic number66which means there are 66 protons and 66 electrons in the atomic structure. Thechemical symbolfor Dysprosium isDy.

is a rare earth element with a metallic silver luster. Dysprosium is used for its high thermal neutron absorption cross-section in making control rods in nuclear reactors, for its high magnetic susceptibility in data storage applications.

[Xe] 4f106s2

67

Ho

Holmium

[Xe] 4f116s2

Holmium

Discoverer: Cleve, Per Theodor

Element Category: Lanthanoids

Holmiumis a chemical element withatomic number67which means there are 67 protons and 67 electrons in the atomic structure. Thechemical symbolfor Holmium isHo.

Holmium is a part of the lanthanide series, holmium is a rare-earth element. Holmium is a relatively soft and malleable silvery-white metal.

[Xe] 4f116s2

68

Er

Erbium

[Xe] 4f126s2

Erbium

Discoverer: Mosander, Carl Gustav

Element Category: Lanthanoids

Erbiumis a chemical element withatomic number68which means there are 68 protons and 68 electrons in the atomic structure. Thechemical symbolfor Erbium isEr.

Erbium is a silvery-white solid metal when artificially isolated, natural erbium is always found in chemical combination with other elements. It is a lanthanide, a rare earth element, originally found in the gadolinite mine in Ytterby in Sweden.

[Xe] 4f126s2

69

Th

Thulium

[Xe] 4f136s2

Thulium

Discoverer: Cleve, Per Teodor

Element Category: Lanthanoids

Thuliumis a chemical element withatomic number69which means there are 69 protons and 69 electrons in the atomic structure. Thechemical symbolfor Thulium isTm.

Thulium is an easily workable metal with a bright silvery-gray luster. It is fairly soft and slowly tarnishes in air. Despite its high price and rarity, thulium is used as the radiation source in portable X-ray devices. Thulium is the thirteenth and third-last element in the lanthanide series.

[Xe] 4f136s2

70

Yb

Ytterbium

[Xe] 4f146s2

Ytterbium

Discoverer: De Marignac, Jean Charles Galissard

Element Category: Lanthanoids

Ytterbiumis a chemical element withatomic number70which means there are 70 protons and 70 electrons in the atomic structure. Thechemical symbolfor Ytterbium isYb.

Because of its closed-shell electron configuration, its density and melting and boiling points differ significantly from those of most other lanthanides.

[Xe] 4f146s2

71

Lu

Lutetium

[Xe] 4f145d16s2

Lutetium

Discoverer: Urbain, Georges

Element Category: Lanthanoids

Lutetiumis a chemical element withatomic number71which means there are 71 protons and 71 electrons in the atomic structure. Thechemical symbolfor Lutetium isLu.

Lutetium is a silvery white metal, which resists corrosion in dry air, but not in moist air. Lutetium is the last element in the lanthanide series, and it is traditionally counted among the rare earths.

[Xe] 4f145d16s2

89

Ac

Actinium

[Rn] 6d17s2

Actinium

Discoverer: Debierne, André

Element Category: Actinoids

Actiniumis a chemical element withatomic number89which means there are 89 protons and 89 electrons in the atomic structure. Thechemical symbolfor Actinium isAc.

Actinium is a soft, silvery-white radioactive metal. Actinium gave the name to the actinide series, a group of 15 similar elements between actinium and lawrencium in the periodic table.

[Rn] 6d17s2

90

Th

Thorium

[Rn] 6d27s2

Thorium

Discoverer: Berzelius, Jöns Jacob

Element Category: Actinoids

Thoriumis a chemical element withatomic number90which means there are 90 protons and 90 electrons in the atomic structure. Thechemical symbolfor Thorium isTh.

Thorium metal is silvery and tarnishes black when exposed to air, forming the dioxide. Thorium is moderately hard, malleable, and has a high melting point. Thorium is a naturally-occurring element and it is estimated to be about three times more abundant than uranium. Thorium is commonly found in monazite sands (rare earth metals containing phosphate mineral).

[Rn] 6d27s2

91

Pa

Protactinium

[Rn] 5f26d17s2

Protactinium

Discoverer: Göhring, Otto and Fajans, Kasimir

Element Category: Actinoids

Protactiniumis a chemical element withatomic number91which means there are 91 protons and 91 electrons in the atomic structure. Thechemical symbolfor Protactinium isPa.

Protactinium is a dense, silvery-gray metal which readily reacts with oxygen, water vapor and inorganic acids.

[Rn] 5f26d17s2

92

U

Uranium

[Rn] 5f36d17s2

Uranium

Discoverer: Klaproth, Martin Heinrich

Element Category: Actinoids

Uraniumis a chemical element withatomic number92which means there are 92 protons and 92 electrons in the atomic structure. Thechemical symbolfor Uranium isU.

Uranium is a silvery-white metal in the actinide series of the periodic table. Uranium is weakly radioactive because all isotopes of uranium are unstable, with half-lives varying between 159,200 years and 4.5 billion years. Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten.

[Rn] 5f36d17s2

93

Np

Neptunium

[Rn] 5f46d17s2

Neptunium

Discoverer: McMillan, Edwin M. and Abelson, Philip H.

Element Category: Actinoids

Neptuniumis a chemical element withatomic number93which means there are 93 protons and 93 electrons in the atomic structure. Thechemical symbolfor Neptunium isNp.

Neptunium metal is silvery and tarnishes when exposed to air. Neptunium is the first transuranic element.

[Rn] 5f46d17s2

94

Pu

Plutonium

[Rn] 5f67s2

Plutonium

Discoverer: Glenn T. Seaborg, Joseph W. Kennedy, Edward M. McMillan, Arthur C. Wohl

Element Category: Actinoids

Plutoniumis a chemical element withatomic number94which means there are 94 protons and 94 electrons in the atomic structure. Thechemical symbolfor Plutonium isPu.

Plutonium is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized.

[Rn] 5f67s2

95

Am

Americium

[Rn] 5f77s2

Americium

Discoverer: Glenn T. Seaborg, Ralph A. James, Leon O. Morgan, Albert Ghiorso

Element Category: Actinoids

Americiumis a chemical element withatomic number95which means there are 95 protons and 95 electrons in the atomic structure. Thechemical symbolfor Americium isAm.

Americium is a transuranic member of the actinide series, in the periodic table located under the lanthanide element europium, and thus by analogy was named after the Americas.

[Rn] 5f77s2

96

Cm

Curium

[Rn] 5f76d 7s2

Curium

Discoverer: Glenn T. Seaborg, Ralph A. James, Albert Ghiorso

Element Category: Actinoids

Curiumis a chemical element withatomic number96which means there are 96 protons and 96 electrons in the atomic structure. Thechemical symbolfor Curium isCm.

Curium is a hard, dense, silvery metal with a relatively high melting point and boiling point for an actinide.

[Rn] 5f76d 7s2

97

Bk

Berkelium

[Rn] 5f97s2

Berkelium

Discoverer: Stanley G. Thompson, Glenn T. Seaborg, Kenneth Street, Jr., Albert Ghiorso

Element Category: Actinoids

Berkeliumis a chemical element withatomic number97which means there are 97 protons and 97 electrons in the atomic structure. Thechemical symbolfor Berkelium isBk.

Berkelium is a member of the actinide and transuranium element series.

[Rn] 5f97s2

98

Cf

Californium

[Rn] 5f107s2

Californium

Discoverer: Stanley G. Thompson, Glenn T. Seaborg, Kenneth Street, Jr., Albert Ghiorso

Element Category: Actinoids

Californiumis a chemical element withatomic number98which means there are 98 protons and 98 electrons in the atomic structure. Thechemical symbolfor Californium isCf.

Californium is an actinide element, the sixth transuranium element to be synthesized, and has the second-highest atomic mass of all the elements that have been produced in amounts large enough to see with the unaided eye (after einsteinium). The most commonly used spontaneous fission neutron source is the radioactive isotope californium-252.

[Rn] 5f107s2

99

Es

Einsteinium

[Rn] 5f117s2

Einsteinium

Discoverer: Albert Ghiorso et. al.

Element Category: Actinoids

Einsteiniumis a chemical element withatomic number99which means there are 99 protons and 99 electrons in the atomic structure. Thechemical symbolfor Einsteinium isEs.

Einsteinium is the seventh transuranic element, and an actinide.

[Rn] 5f117s2

100

Fm

Fermium

[Rn] 5f127s2

Fermium

Discoverer: Albert Ghiorso et. al.

Element Category: Actinoids

Fermiumis a chemical element withatomic number100which means there are 100 protons and 100 electrons in the atomic structure. Thechemical symbolfor Fermium isFm.

Fermium is a member of the actinide series. It is the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities.

[Rn] 5f127s2

101

Md

Mendelevium

[Rn] 5f137s2

Mendelevium

Discoverer: Stanley G. Thompson, Glenn T. Seaborg, Bernard G. Harvey, Gregory R. Choppin, Albert Ghiorso

Element Category: Actinoids

Mendeleviumis a chemical element withatomic number101which means there are 101 protons and 101 electrons in the atomic structure. Thechemical symbolfor Mendelevium isMd.

Mendelevium is a metallic radioactive transuranic element in the actinide series, it is the first element that currently cannot be produced in macroscopic quantities.

[Rn] 5f137s2

102

No

Nobelium

[Rn] 5f147s2

Nobelium

Discoverer: Albert Ghiorso, Glenn T. Seaborg, Torbørn Sikkeland, John R. Walton

Element Category: Actinoids

Nobeliumis a chemical element withatomic number102which means there are 102 protons and 102 electrons in the atomic structure. Thechemical symbolfor Nobelium isNo.

Nobelium is the tenth transuranic element and is the penultimate member of the actinide series. Like all elements with atomic number over 100, nobelium can only be produced in particle accelerators by bombarding lighter elements with charged particles.

[Rn] 5f147s2

103

Lr

Lawrencium

[Rn] 5f147s2 7p1

Lawrencium

Discoverer: Albert Ghiorso, Torbjørn Sikkeland, Almon E. Larsh, Robert M. Latimer

Element Category: Actinoids

Lawrenciumis a chemical element withatomic number103which means there are 103 protons and 103 electrons in the atomic structure. Thechemical symbolfor Lawrencium isLr.

Lawrencium is the final member of the actinide series. Like all elements with atomic number over 100, lawrencium can only be produced in particle accelerators by bombarding lighter elements with charged particles.

[Rn] 5f147s2 7p1

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