Cadmium
Cadmium is a soft, bluish-white transition metal, closely related to zinc in the periodic table and often found alongside it in nature. It was once common in rechargeable batteries and bright yellow and red pigments, but its toxicity and tendency to accumulate in the body have pushed industry toward safer substitutes over recent decades. Today its use is tightly restricted in most consumer products.
- Group · Period
- 12 · 5
- At room temp
- solid
- Melts at
- 594.22 K
- Density
- 8.69 g/cm³
- Discovered
- 1817
Uses
Cadmium’s most familiar historical use was in nickel-cadmium rechargeable batteries, which powered cordless tools and electronics for decades before being largely displaced by nickel-metal hydride and lithium-ion technology. It was also prized as a pigment — cadmium yellow and cadmium red gave paints and ceramics an intense, stable color that was hard to match with other materials. Cadmium plating was once widely used to protect steel hardware, especially aircraft components, from corrosion.
Because cadmium absorbs neutrons efficiently, it’s also used in control rods that regulate the nuclear fission reaction inside some nuclear reactors. Most of these uses have narrowed considerably in recent decades as cadmium’s toxicity became better understood, and today it’s mainly used in specialized applications where a safer substitute isn’t yet practical.
History
Cadmium was discovered in 1817 by the German chemist Friedrich Stromeyer, who noticed that some samples of zinc carbonate behaved differently from others when heated and traced the difference to a previously unrecognized metal hidden within the ore. He named it cadmium, from cadmia, the old Latin and Greek name for zinc ore, reflecting how closely the two metals occur together in nature. For much of the twentieth century cadmium found wide industrial use, but growing understanding of its health risks has since made caution, rather than adoption, the dominant theme of its more recent history.
Fun facts
- Cadmium is toxic and builds up in the kidneys and bones over time, which is why its use in everyday products is now heavily restricted.
- Cadmium yellow and cadmium red were favorite pigments of painters like Monet and Van Gogh, prized for their intensity and stability.
- Nickel-cadmium (NiCd) rechargeable batteries, once common in power tools and cordless electronics, relied on cadmium as a key electrode material.
Frequently asked questions
Why is cadmium banned or restricted in so many products now?
Cadmium is a cumulative toxin — the body has no efficient way to get rid of it, so repeated exposure lets it build up in the kidneys and bones over years and cause serious harm. That risk is why regulations like RoHS restrict cadmium in electronics, toys and other consumer goods, pushing manufacturers toward safer alternatives such as lithium-ion batteries and cadmium-free pigments.
What was cadmium yellow, and is it still used?
Cadmium yellow and cadmium red are pigments made from cadmium sulfide and cadmium selenide compounds, valued historically for their bold, long-lasting color. Well-known painters used them extensively, and artist-grade cadmium paints are still sold today, but industrial and household use of cadmium pigments has declined sharply because of toxicity concerns.
How was cadmium discovered?
German chemist Friedrich Stromeyer found it in 1817 while investigating zinc carbonate samples that behaved oddly when heated. He isolated a new metal hiding within the zinc mineral and named it after cadmia, an old name for zinc ore — a fitting name, since cadmium and zinc are chemically similar and almost always found together in nature.
Compounds
4 notable compounds containing Cd
- CdCl2salt
Cadmium chloride
A white, water-soluble salt used mainly as a laboratory and industrial source of dissolved cadmium ions. It forms a distinctive layered crystal structure that is often cited as a reference lattice in chemistry.
Used for: Precursor for depositing cadmium sulfide and cadmium telluride films
- CdOoxide
Cadmium oxide
A brownish-black crystalline oxide that forms when cadmium metal burns in air. It behaves as a wide-bandgap semiconductor as well as an industrial chemical intermediate.
Used for: Electroplating baths and nickel-cadmium battery electrodes
- CdSpigment
Cadmium sulfide
A bright yellow-orange semiconducting solid formed from cadmium and sulfur. Its strong, stable color made it a prized artists' pigment long before its toxicity became a health concern.
Used for: Historic 'cadmium yellow' pigment and light-sensitive photoresistors
- CdTesemiconductor
Cadmium telluride
A crystalline compound of cadmium and tellurium whose band gap closely matches the peak intensity of sunlight, making it efficient at converting light directly into electricity.
Used for: Thin-film solar panels and infrared detector windows
Isotopes
41 known isotopes
Swipe to see all columns →
| Isotope | Natural abundance | Half-life | Decay mode | Mass excess | Binding energy / nucleon | Decay width |
|---|---|---|---|---|---|---|
| Cd-106 stable | 1.245% | Stable | — | -87,132.15 keV | 8,539.05 keV | — |
| Cd-108 stable | 0.888% | Stable | — | -89,252.42 keV | 8,550.02 keV | — |
| Cd-110 stable | 12.47% | Stable | — | -90,347.97 keV | 8,551.28 keV | — |
| Cd-111 stable | 12.795% | Stable | — | -89,252.25 keV | 8,537.08 keV | — |
| Cd-112 stable | 24.109% | Stable | — | -90,574.86 keV | 8,544.73 keV | — |
| Cd-113 | 12.227% | 8.04E15 Y | Beta-minus decay (100%) | -89,043.29 keV | 8,526.99 keV | 1.80 × 10-39 eV |
| Cd-114 stable | 28.754% | Stable | — | -90,014.93 keV | 8,531.51 keV | — |
| Cd-116 | 7.512% | 3.3E+19 Y | Double beta-minus decay | -88,712.49 keV | 8,512.35 keV | 4.38 × 10-43 eV |
Show all 41 isotopes
| Cd-94 | — | 760 ns | ECP, Electron capture / beta-plus decay | -40,440 keV | 8,102 keV | 6.00 × 10-10 eV |
| Cd-95 | — | 32 ms | Beta-plus decay (100%), Beta-plus, proton emission (4.5%) | -47,056 keV | 8,171 keV | 1.43 × 10-14 eV |
| Cd-96 | — | 1.03 s | Electron capture / beta-plus decay (100%) | -55,572 keV | 8,259 keV | 4.43 × 10-16 eV |
| Cd-97 | — | 2.8 s | Electron capture (100%), ECP | -60,734.03 keV | 8,310.3 keV | 1.63 × 10-16 eV |
| Cd-98 | — | 9.3 s | Electron capture / beta-plus decay (100%), ECP (0.029%) | -67,636.43 keV | 8,378.3 keV | 4.91 × 10-17 eV |
| Cd-99 | — | 16 s | Electron capture / beta-plus decay (100%), Beta-plus, proton emission (0.17%), Beta-plus, alpha emission (0.0001%) | -69,931.13 keV | 8,398.37 keV | 2.85 × 10-17 eV |
| Cd-100 | — | 49.1 s | Electron capture / beta-plus decay (100%) | -74,194.6 keV | 8,437.74 keV | 9.29 × 10-18 eV |
| Cd-101 | — | 1.36 m | Electron capture / beta-plus decay (100%) | -75,836.47 keV | 8,450.37 keV | 5.59 × 10-18 eV |
| Cd-102 | — | 5.5 m | Electron capture / beta-plus decay (100%) | -79,659.7 keV | 8,484.13 keV | 1.38 × 10-18 eV |
| Cd-103 | — | 7.3 m | Electron capture / beta-plus decay (100%) | -80,651.63 keV | 8,489.75 keV | 1.04 × 10-18 eV |
| Cd-104 | — | 57.7 m | Electron capture / beta-plus decay (100%) | -83,968.39 keV | 8,517.62 keV | 1.32 × 10-19 eV |
| Cd-105 | — | 55.5 m | Electron capture / beta-plus decay (100%) | -84,333.85 keV | 8,516.85 keV | 1.37 × 10-19 eV |
| Cd-107 | — | 6.50 h | Electron capture / beta-plus decay (100%) | -86,990.33 keV | 8,533.35 keV | 1.95 × 10-20 eV |
| Cd-109 | — | 461.9 d | Electron capture (100%) | -88,504.33 keV | 8,538.76 keV | 1.14 × 10-23 eV |
| Cd-115 | — | 53.46 h | Beta-minus decay (100%) | -88,084.48 keV | 8,510.73 keV | 2.37 × 10-21 eV |
| Cd-117 | — | 2.49 h | Beta-minus decay (100%) | -86,418.4 keV | 8,488.97 keV | 5.09 × 10-20 eV |
| Cd-118 | — | 50.3 m | Beta-minus decay (100%) | -86,701.65 keV | 8,487.84 keV | 1.51 × 10-19 eV |
| Cd-119 | — | 2.69 m | Beta-minus decay (100%) | -83,976.94 keV | 8,461.44 keV | 2.83 × 10-18 eV |
| Cd-120 | — | 50.80 s | Beta-minus decay (100%) | -83,957.37 keV | 8,458.02 keV | 8.98 × 10-18 eV |
| Cd-121 | — | 13.5 s | Beta-minus decay (100%) | -81,073.84 keV | 8,431 keV | 3.38 × 10-17 eV |
| Cd-122 | — | 5.24 s | Beta-minus decay (100%) | -80,612.38 keV | 8,424.27 keV | 8.71 × 10-17 eV |
| Cd-123 | — | 2.10 s | Beta-minus decay (100%) | -77,414.18 keV | 8,395.4 keV | 2.17 × 10-16 eV |
| Cd-124 | — | 1.25 s | Beta-minus decay (100%) | -76,699.44 keV | 8,387.02 keV | 3.65 × 10-16 eV |
| Cd-125 | — | 0.68 s | Beta-minus decay (100%) | -73,348.09 keV | 8,357.68 keV | 6.71 × 10-16 eV |
| Cd-126 | — | 0.514 s | Beta-minus decay (100%) | -72,255.73 keV | 8,346.74 keV | 8.88 × 10-16 eV |
| Cd-127 | — | 0.37 s | Beta-minus decay (100%) | -68,741.2 keV | 8,316.9 keV | 1.23 × 10-15 eV |
| Cd-128 | — | 0.28 s | Beta-minus decay (100%) | -67,238.25 keV | 8,303.24 keV | 1.63 × 10-15 eV |
| Cd-129 | — | 154 ms | Beta-minus decay (100%), Beta-minus, neutron emission (0%) | -63,122.14 keV | 8,269.53 keV | 2.96 × 10-15 eV |
| Cd-130 | — | 162 ms | Beta-minus decay (100%), Beta-minus, neutron emission (3.5%) | -61,117.6 keV | 8,252.59 keV | 2.82 × 10-15 eV |
| Cd-131 | — | 68 ms | Beta-minus decay (100%), Beta-minus, neutron emission (3.5%) | -55,211.76 keV | 8,206.12 keV | 6.71 × 10-15 eV |
| Cd-132 | — | 84 ms | Beta-minus decay (100%), Beta-minus, neutron emission (60%), B-2N | -50,465.43 keV | 8,169.14 keV | 5.43 × 10-15 eV |
| Cd-133 | — | 57 ms | Beta-minus decay (100%), Beta-minus, neutron emission, B-2N | -44,140 keV | 8,121 keV | 8.00 × 10-15 eV |
| Cd-134 | — | 65 ms | Beta-minus decay (100%), Beta-minus, neutron emission, B-2N | -39,460 keV | 8,086 keV | 7.02 × 10-15 eV |