Zinc

Symbol: Zn
Atomic Number: 30
Atomic Weight: 65.39
Element Classification: Transition Metal
Discovered By: Known to the ancients.
Discovery Date: n/a (Germany)
Name Origin: German: zink (German for tin).

Density (g/cc): 7.133
Melting Point (K): 692.73
Boiling Point (K): 1180
Appearance: Bluish-silver, ductile metal
Atomic Radius (pm): 138
Atomic Volume (cc/mol): 9.2
Covalent Radius (pm): 125
Ionic Radius: 74 (+2e)
Specific Heat (@20C J/g mol): 0.388
Fusion Heat (kJ/mol): 7.28
Evaporation Heat (kJ/mol): 114.8
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 234.00
Pauling Negativity Number: 1.65
First Ionizing Energy (kJ/mol): 905.8
Oxidation States: 2
Electronic Configuration: [Ar] 3d10 4s2
Lattice Structure: Hexagonal (HEX)
Lattice Constant (): 2.660
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 2.5
Brinell Hardness [/MN m-2]: 412

Note: Zinc, with a hexagonal close-packed crystal structure, is quite prone to mechanical twin formation if sectioning or grinding is performed too aggressively. It is harder, however, than tin or lead and tends to be brittle. Zinc is widely used to coat sheet steel (galvanized steel) for corrosion protection, and is a common metallographic subject. Pure zinc is very difficult to prepare. 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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