Cadmium

Symbol: Cd
Atomic Number: 48
Atomic Weight: 112.411
Element Classification: Transition Metal
Discovered By: Fredrich Stromeyer
Discovery Date: 1817 (Germany)
Name Origin: Greek: kadmeia (ancient name for calamine (zinc oxide)).

Density (g/cc): 8.65
Melting Point (K): 594.1
Boiling Point (K): 1038
Appearance: Soft, malleable, blue-white metal
Atomic Radius (pm): 154
Atomic Volume (cc/mol): 13.1
Covalent Radius (pm): 148
Ionic Radius: 97 (+2e)
Specific Heat (@20C J/g mol): 0.232
Fusion Heat (kJ/mol): 6.11
Evaporation Heat (kJ/mol): 59.1
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 120.00
Pauling Negativity Number: 1.69
First Ionizing Energy (kJ/mol): 867.2
Oxidation States: 2
Electronic Configuration: [Kr] 4d10 5s2
Lattice Structure: Hexagonal (HEX)
Lattice Constant (): 2.980
Lattice C/A Ratio: 1.886

Mineral Hardness [no units]: 2.0
Brinell Hardness [/MN m-2]: 203

Note: Cadmium, with a hexagonal close-packed crystal structure, is quite prone to mechanical twin formation if sectioning or grinding is performed too aggressively. Due to their low melting points, and low recrystallization temperatures, cold setting resins are usually recommended as recrystallization may occur during hot compression mounting. Heating of surfaces during grinding must be minimized. Grinding of these metals is always difficult, as SiC particles tend to embed heavily. Many authors have recommended coating the SiC paper surface with bees wax, but this does not solve the problem. Embedding is most common with the finer grit size papers. Diamond is not a very effective abrasive with these metals. Alumina works quite well.

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