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48Cd112.41

Element 48, a transition metal

Cadmium

A soft metal behind brilliant yellow and red paints and rechargeable batteries, and a toxic one behind a mass poisoning in Japan.

At a glance

Symbol
Cd
Atomic number
48
Average atomic mass
112.41
Group
12
Period
5
Family
transition metal
Electron configuration
[Kr] 4d¹⁰ 5s²
Electronegativity
1.69
Common ions
Cd²⁺

On the table

Periodic table with Cadmium highlighted123456789101112131415161718123456757-7189-103HHeLiBeBCNOFNeNaMgAlSiPSClArKCaScTiVCrMnFeCoNiCuZnGaGeAsSeBrKrRbSrYZrNbMoTcRuRhPdAgCdInSnSbTeIXeCsBaLaCePrNdPmSmEuGdTbDyHoErTmYbLuHfTaWReOsIrPtAuHgTlPbBiPoAtRnFrRaAcThPaUNpPuAmCmBkCfEsFmMdNoLrRfDbSgBhHsMtDsRgCnNhFlMcLvTsOg

Period 5, group 12. The other transition metals are tinted, and every cell opens its own article.

Electrons and bonding

Cadmium gives up its two 5s electrons to form Cd²⁺, its only common ion, much like zinc above it.

Properties

State at 25 °C
solid
What it looks like
soft, bluish-white metal
Melting point
321.1 °C
Boiling point
767 °C
Density
8.69 g/cm³

Where it is found

No ores are mined for cadmium alone. It occurs in zinc ores, especially sphalerite, and is recovered during zinc refining.

Discovery and name

Friedrich Stromeyer found it in 1817 while investigating zinc carbonate that turned yellow when heated. The name comes from the Latin cadmia, an old name for zinc carbonate ore.

What it is used for

Nickel-cadmium rechargeable batteries used most of it, though they are being phased out. Cadmium telluride makes thin-film solar panels, cadmium pigments give artists' paints brilliant yellows, oranges and reds, and cadmium absorbs neutrons in some reactor control rods.

In compounds

CdScadmium sulfide, cadmium yellowCdTecadmium telluride, solar panelsCdSecadmium selenide, quantum dotsCd(OH)₂cadmium hydroxide, a battery electrode

Handle with care

Toxic, and a cause of cancer. Cadmium from mining waste in the Jinzū River basin of Japan caused itai-itai disease in the 20th century, which softened bones and caused severe pain.