Cadmium

Cadmium is a chemical element wi the seembol Cd an atomic nummer 48. This saft, bluish-white metal is chemically seemilar tae the twa ither stable metals in group 12, zinc an mercur. Lik zinc, it prefers oxidation state +2 in maist o its compoonds an lik mercur it shaws a law meltin pynt compared tae transeetion metals. Cadmium an its congeners are nae always considered transeetion metals, in that thay dae nae hae pairtly filled d or f electron shells in the elemental or common oxidation states. The average concentration o cadmium in the Yird's crust is atween 0.1 an 0.5 pairts per million (ppm). It wis discovered in 1817 simultaneously bi Stromeyer an Hermann, baith in Germany, as an impurity in zinc carbonate.

Cadmium, ₄₈Cd

Cadmium
Pronunciation	/ˈkædmiəm/ ​(KAD-mee-əm)
Appearance	sillery bluish-gray metallic
Standard atomic weight Ar, std(Cd)	7002112414000000000♠112.414(4)
Cadmium in the periodic cairt
Hydrogen Helium Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Airn Cobalt Nickel Capper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Siller (element) Cadmium Indium Tin Antimony Tellurium Iodine Xenon Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gowd Mercur (element) Thallium Leid (element) Bismuth Polonium Astatine Radon Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Ununtrium Flerovium Ununpentium Livermorium Ununseptium Ununoctium Zn ↑ Cd ↓ Hg siller ← cadmium → indium
Atomic nummer (Z)	48
Group	group 12
Period	period 5
Block	d-block
Element category	Post-transeetion metal
Electron confeeguration	[Kr] 4d10 5s2
Electrons per shell	2, 8, 18, 18, 2
Pheesical properties
Phase at STP	solit
Meltin pynt	594.22 K ​(321.07 °C, ​609.93 °F)
Bylin pynt	1040 K ​(767 °C, ​1413 °F)
Density (near r.t.)	8.65 g/cm3
when liquid (at m.p.)	7.996 g/cm3
Heat o fusion	6.21 kJ/mol
Heat o vapourisation	99.87 kJ/mol
Molar heat capacity	26.020 J/(mol·K)
Vapour pressur P (Pa) 1 10 100 1 k 10 k 100 k at T (K) 530 583 654 745 867 1040
Atomic properties
Oxidation states	−2, +1, +2 (a mildly basic oxide)
Electronegativity	Pauling scale: 1.69
Atomic radius	empirical: 151 pm
Covalent radius	144±9 pm
Van der Waals radius	158 pm
Colour lines in a spectral range Spectral lines o cadmium
Ither properties
Naitural occurrence	primordial
Creestal structur	​hexagonal close-packed (hcp)
Speed o soond thin rod	2310 m/s (at 20 °C)
Thermal expansion	30.8 µm/(m·K) (at 25 °C)
Thermal conductivity	96.6 W/(m·K)
Electrical resistivity	(22 °C) 72.7 n Ω·m
Magnetic orderin	diamagnetic
Young's modulus	50 GPa
Shear modulus	19 GPa
Bulk modulus	42 GPa
Poisson ratio	0.30
Mohs haurdness	2.0
Brinell haurdness	203 MPa
CAS Nummer	7440-43-9
History
Diskivery	Karl Samuel Leberecht Hermann an Friedrich Stromeyer (1817)
First isolation	Karl Samuel Leberecht Hermann an Friedrich Stromeyer (1817)
Named by	Friedrich Stromeyer (1817)
Main isotopes o cadmium
Iso­tope Abun­dance Hauf-life (t1/2) Decay mode Pro­duct 106Cd 1.25% >4.1×1020 y (β+β+) 106Pd 107Cd syn 6.5 h ε 107Ag 108Cd 0.89% >4.1×1017 y (β+β+) 108Pd 109Cd syn 462.6 d ε 109Ag 110Cd 12.49% - (SF) 111Cd 12.8% - (SF) 112Cd 24.13% - (SF) 113Cd 12.22% 7.7×1015 y β− 113In 113mCd syn 14.1 y β− 113In IT 113Cd 114Cd 28.73% >6.4×1018 y (β−β−) 114Sn 115Cd syn 53.46 h β− 115In 116Cd 7.49% 3.1×1019 y β−β− 116Sn
Decay modes in parentheses are predictit, but hae nae yet been observed