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About Cadmium

Cadmium Bohr

In nature, cadmium is most commonly found as a minor component of zinc ores. This fact led to its discovery in 1817 by Friedrich Stromeyer, who was at the time looking for contaminants in a sample of the zinc carbonate mineral calamine, from which the name of the element was subsequently derived.

Cadmium found a variety of applications soon after its discovery. The first notable use of cadmium was in red, orange, and yellow pigments based on cadmium sulfides and selenides, which started on a small scale as early as the 1840’s. Cadmium pigments are valued for their vividness and permanence, and at the time of their introduction there were few options for stable pigments in this color range. As industrial scale production of the metal started in the earlier twentieth century, cadmium pigments gained in popularity and other applications followed. Since cadmium is resistant to corrosion it can be used as a protective coating on more easily corroded metals such as steel, deposited by an electroplating process. Nickel-cadmium (NiCd) batteries were first invented in 1899, but became commonly produced starting in the mid-1940’s. For the next fifty years, they were the primary rechargeable batteries available for consumer electronics. Cadmium can also be a component of silver-based solder alloys that are versatile and have high strength along with a uniquely low melting point, and cadmium compounds can be used to stabilize PVC plastics, greatly increasing their resistance to heat and general wear.

Unfortunately, using cadmium for all of these applications had one major downside: cadmium and many of its compounds are extremely toxic. Poisoning by the metal’s fumes or cadmium-laden dust is often acute, producing severe flu-like symptoms, respiratory problems, and damage to the liver and kidneys within hours of exposure. Acute organ damage can also result from ingestion of large amounts of cadmium compounds, but long term low-level exposure can also lead to insidious damage, producing progressive kidney disease, gout, and dangerously weak bones which lead to severe pain and fractures.

Poisoning is obviously a risk for welders exposed to fumes, artists working with cadmium pigments, miners and metal refiners working with zinc ores, and workers in plants producing cadmium-laden products, but even more alarming is the risk to the general public. Cadmium in industrial waste, landfills, and mines easily leaches into groundwater, and from there can be consumed in drinking water or accumulate in crops. All plants can absorb some cadmium from the soil, but some are particularly prone to concentrating the metal, which sometimes leads to tragic mass poisonings.

Cadmium's toxicity concerns have lead to new workplace safety regulations, battery recycling programs, and a substantial decline in traditional uses of the metal. Alternative pigments such as cerium sulphide and azo pigments are now available for many applications, though some fine artist's paints still include cadmium. In most applications of corrosion-resistant thin films, zinc or aluminum plating can serve the same purpose as cadmium. Few solder formulas still include cadmium, and alternative stabilizers have been developed for the manufacture of PVC products. Finally, nickel metal hydride(NiMH) and lithium ion batteries are now becoming economically viable and functionally comparable alternatives to Ni-Cd for rechargeable batteries in consumer electronics, though Ni-Cd batteries still have advantages to recommend them for some specialized applications.

A relatively new application for cadmium in compound semiconductors is becoming increasingly relevant. Cadmium can form II-VI class semiconducting compounds with selenium, tellurium, and sulfur, and can also be a component of several ternary semiconductors. The largest current use of cadmium semiconductors is in cadmium telluride thin-film photovoltaics, but they are also used in radiation detectors, electro-optic modulators, optical windows and lenses, photoresistors, and lasers. Additionally, ongoing research into nanoscale cadmium semiconductor crystals such as cadmium selenide quantum dots has shown promise for a variety of applications, including higher-efficiency LED-type lighting.

Cadmium is relatively rare and there are no common cadmium ores, so today the element is still obtained commercially as a byproduct of zinc mining. Cadmium sulfide is the compound most commonly found in zinc ores, and as it is easy to isolate and purify, it is the primary source of cadmium for industrial applications.

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Cadmium is a key component in battery production, certain pigments and coatings, and is commonly used in electroplating. Cadmium oxide is used in phosphors for television picture tubes. Cadmium sulfide (CdS) is used as a photoconductive surface coating for photocopier drums. Cadmium is also used High Purity (99.999%) Cadmium Oxide (CdO) Powderto absorb neutrons in nuclear reactors. Cadmium in glass and ceramic glazes create a distinctive cadmium yellow. High Purity (99.99999%) Cadmium (Cd) Sputtering TargetCadmium is available as metal and compounds with purities from 99% to 99.999% (ACS grade to ultra-high purity). Elemental or metallic forms include pellets, rod, wire and granules for evaporation source material purposes. Cadmium oxide is available in powder and dense pellet form for such uses as optical coating and thin film applications. Oxides tend to be insoluble. Fluorides are another insoluble form for uses in which oxygen is undesirable such as metallurgy, chemical and physical vapor deposition and in some optical coatings. Cadmium is also available in soluble forms including chlorides, nitrates and acetates. These compounds can be manufactured as solutions at specified stoichiometries.

Cadmium Properties

Cadmium(Cd) atomic and molecular weight, atomic number and elemental symbolCadmium is a Block D, Group 12, Period 5 element. Cadmium Bohr ModelThe number of electrons in each of Cadmium's shells is 2, 8, 18, 18, 2 and its electronic configuration is [Kr] 4d10 5s2. Elemental CadmiumThe cadmium atom has a radius of and its Van der Waals radius is In its elemental form, CAS 7440-43-9, cadmium has a silvery bluish gray metallic appearance. Cadmium makes up about 0.1 ppm of the earth's crust. No significant deposits of cadmium containing ores are known, however, it is sometimes found in its metallic form. It is a common impurity in zinc ores and is isolated during the production of zinc. Cadmium was first discovered by Friedrich Stromeyer in 1817. The name cadmium originates from the Latin word 'cadmia' and the Greek word 'kadmeia'.

Symbol: Cd
Atomic Number: 48
Atomic Weight: 112.411
Element Category: transition metal
Group, Period, Block: 12, 5, d
Color: bluish-white/ silvery gray metallic
Other Names: Cadmio, Cádmio, Kadmium,
Melting Point: 321.07 °C, 609.93 °F, 594.22 K
Boiling Point: 767 °C, 1413 °F, 1040 K
Density: 8.65 g/cm3
Liquid Density @ Melting Point: 7.996 g/cm3
Density @ 20°C: 8.65 g/cm3
Density of Solid: 8650 kg·m3
Specific Heat: 0.23 (kJ/kg K)
Superconductivity Temperature: 0.517 [or -272.633 °C (-458.74 °F)] K
Triple Point: N/A
Critical Point: N/A
Heat of Fusion (kJ·mol-1): 6.11
Heat of Vaporization (kJ·mol-1): 100
Heat of Atomization (kJ·mol-1): 112.05
Thermal Conductivity: 96.6 W·m-1·K-1
Thermal Expansion: (25 °C) 30.8 µm·m-1·K-1
Electrical Resistivity: (22 °C) 72.7 nΩ·m
Tensile Strength: N/A
Molar Heat Capacity: 26.020 J·mol-1·K-1
Young's Modulus: 50 GPa
Shear Modulus: 19 GPa
Bulk Modulus: 42 GPa
Poisson Ratio: 0.3
Mohs Hardness: 2
Vickers Hardness: N/A
Brinell Hardness: 203 MPa
Speed of Sound: (20 °C) 2310 m·s-1
Pauling Electronegativity: 1.69
Sanderson Electronegativity: 1.98
Allred Rochow Electronegativity: 1.46
Mulliken-Jaffe Electronegativity: 1.53 (sp orbital)
Allen Electronegativity: N/A
Pauling Electropositivity: 2.31
Reflectivity (%): 67
Refractive Index: N/A
Electrons: 48
Protons: 48
Neutrons: 64
Electron Configuration: [Kr] 4d10 5s2
Atomic Radius: 151 pm
Atomic Radius,
non-bonded (Å):
Covalent Radius: 144±9 pm
Covalent Radius (Å): 1.4
Van der Waals Radius: 158 pm
Oxidation States: 2, 1 (mildly basic oxide)
Phase: Solid
Crystal Structure: hexagonal close-packed
Magnetic Ordering: diamagnetic
Electron Affinity (kJ·mol-1) Not stable
1st Ionization Energy: 867.78 kJ·mol-1
2nd Ionization Energy: 1631.42 kJ·mol-1
3rd Ionization Energy: 3616.30 kJ·mol-1
CAS Number: 7440-43-9
EC Number: 231-152-8
MDL Number: MFCD00010914
Beilstein Number: 8137359
SMILES Identifier: [Cd]
InChI Identifier: InChI=1S/Cd
PubChem CID: 23973
ChemSpider ID: 22410
Earth - Total: 16.4 ppb
Mercury - Total: 0.19 ppb
Venus - Total: 17.2 ppb
Earth - Seawater (Oceans), ppb by weight: 0.05
Earth - Seawater (Oceans), ppb by atoms: 0.0028
Earth -  Crust (Crustal Rocks), ppb by weight: 150
Earth -  Crust (Crustal Rocks), ppb by atoms: 30
Sun - Total, ppb by weight: 6
Sun - Total, ppb by atoms: 0.07
Stream, ppb by weight: N/A
Stream, ppb by atoms: N/A
Meterorite (Carbonaceous), ppb by weight: 450
Meterorite (Carbonaceous), ppb by atoms: 60
Typical Human Body, ppb by weight: 700
Typical Human Body, ppb by atom: 39
Universe, ppb by weight: 2
Universe, ppb by atom: 0.02
Discovered By: Karl Samuel Leberecht Hermann and Friedrich Stromeyer
Discovery Date: 1817
First Isolation: Karl Samuel Leberecht Hermann and Friedrich Stromeyer (1817)

Health, Safety & Transportation Information for Cadmium

Cadmium and its compounds are toxic. Safety data for Cadmium and its compounds can vary widely depending on the form. For potential hazard information, toxicity, and road, sea and air transportation limitations, such as DOT Hazard Class, DOT Number, EU Number, NFPA Health rating and RTECS Class, please see the specific material or compound referenced in the Products tab. The below information applies to elemental (metallic) Cadmium.

Safety Data
Material Safety Data Sheet MSDS
Signal Word Danger
Hazard Statements H330-H341-H350-H361fd-H372-H410
Hazard Codes T+,N
Risk Codes 45-26-48/23/25-50/53-62-63-68
Safety Precautions 53-45-60-61
RTECS Number EU9800000
Transport Information UN 2570 6.1/PG 1
WGK Germany 3
Globally Harmonized System of
Classification and Labelling (GHS)
Environment-Hazardous to the aquatic environment Health Hazard Skull and Crossbones-Acute Toxicity

Cadmium Isotopes

Naturally occurring cadmium (Cd) has six stable isotopes: 106Cd, 108Cd, 110Cd, 111Cd, 112Cd, and 114Cd.

Nuclide Isotopic Mass Half-Life Mode of Decay Nuclear Spin Magnetic Moment Binding Energy (MeV) Natural Abundance
(% by atom)
95Cd 94.94987(64)# 5# ms Unknown 9/2+# N/A 761.13 -
96Cd 95.93977(54)# 1# s ß+ to 96Ag 0+ N/A 778.53 -
97Cd 96.93494(43)# 2.8(6) s ß+ to 97Ag; ß+ + p to 96Ag 9/2+# N/A 791.26 -
98Cd 97.92740(8) 9.2(3) s ß+ to 98Ag; ß+ + p to 97Ag 0+ N/A 805.86 -
99Cd 98.92501(22)# 16(3) s ß+ to 99Ag; ß+ + p to 98Ag; ß+ + a to 98Ag (5/2+) N/A 815.81 -
100Cd 99.92029(10) 49.1(5) s ß+ to 100Ag 0+ N/A 828.54 -
101Cd 100.91868(16) 1.36(5) min ß+ to 101Ag (5/2+) N/A 845.94 -
102Cd 101.91446(3) 5.5(5) min ß+ to 102Ag 0+ N/A 854.02 -
103Cd 102.913419(17) 7.3(1) min ß+ to 103Ag 5/2+ N/A 862.09 -
104Cd 103.909849(10) 57.7(10) min ß+ to 104Ag 0+ N/A 879.49 -
105Cd 104.909468(12) 55.5(4) min ß+ to 105Ag 5/2+ N/A 887.57 -
106Cd 105.906459(6) Observationally Stable - 0+ N/A 895.65 1.25
107Cd 106.906618(6) 6.50(2) h EC to 107Ag 5/2+ -0.615055 903.73 -
108Cd 107.904184(6) Observationally Stable - 0+ N/A 911.8 0.89
109Cd 108.904982(4) 461.4(12) d EC to 109Ag 5/2+ -0.827846 919.88 -
110Cd 109.9030021(29) STABLE - 0+ N/A 927.96 12.49
111Cd 110.9041781(29) STABLE - 1/2+ -0.5948857 936.04 12.8
112Cd 111.9027578(29) STABLE - 0+ N/A 944.12 24.13
113Cd 112.9044017(29) 7.7(3)E+15 y ß- to 113In 1/2+ -0.6223005 952.2 12.22
114Cd 113.9033585(29) Observationally Stable - 0+ N/A 960.28 28.73
115Cd 114.9054310(29) 53.46(5) h ß- to 115Cd 1/2+ -1.087 968.36 -
116Cd 115.904756(3) 3.1(4)E+19 y ß- to 116Sn 0+ N/A 976.43 7.49
117Cd 116.907219(4) 2.49(4) h ß- to 117Cd 1/2+ N/A 984.51 -
118Cd 117.906915(22) 50.3(2) min ß- to 118Cd 0+ N/A 992.59 -
119Cd 118.90992(9) 2.69(2) min ß- to 119Cd (3/2+) N/A 1000.67 -
120Cd 119.90985(2) 50.80(21) s ß- to 120Cd 0+ N/A 1008.75 -
121Cd 120.91298(9) 13.5(3) s ß- to 121Cd (3/2+) N/A 1007.51 -
122Cd 121.91333(5) 5.24(3) s ß- to 122Cd 0+ N/A 1015.59 -
123Cd 122.91700(4) 2.10(2) s ß- to 123Cd (3/2)+ N/A 1023.67 -
124Cd 123.91765(7) 1.25(2) s ß- to 124Cd 0+ N/A 1031.75 -
125Cd 124.92125(7) 0.65(2) s ß- to 125Cd (3/2+)# N/A 1030.51 -
126Cd 125.92235(6) 0.515(17) s ß- to 126Cd 0+ N/A 1038.59 -
127Cd 126.92644(8) 0.37(7) s ß- to 127Cd (3/2+) N/A 1046.67 -
128Cd 127.92776(32) 0.28(4) s ß- to 128Cd 0+ N/A 1054.75 -
129Cd 128.93215(32)# 242(8) ms ß- to 129Cd; IT 3/2+# N/A 1053.51 -
130Cd 129.9339(3) 162(7) ms ß- to 130Cd; ß- + n to 129Cd; 0+ N/A 1061.59 -
131Cd 130.94067(32)# 68(3) ms Unknown 7/2-# N/A 1060.35 -
132Cd 131.94555(54)# 97(10) ms Unknown 0+ N/A 1068.43 -