Bismuth

Symbol: Bi
Atomic Number: 83
Atomic Weight: 208.98037
Element Classification: Other Metal
Discovered By: Known to the ancients.
Discovery Date: n/a (Unknown)
Name Origin: German: bisemutum, (white mass), Now spelled wismut.

Density (g/cc): 9.747
Melting Point (K): 544.5
Boiling Point (K): 1883
Appearance: Hard, brittle, steel-gray metal with a pinkish tinge
Atomic Radius (pm): 170
Atomic Volume (cc/mol): 21.3
Covalent Radius (pm): 146
Ionic Radius: 74 (+5e) 96 (+3e)
Specific Heat (@20C J/g mol): 0.124
Fusion Heat (kJ/mol): 11.00
Evaporation Heat (kJ/mol): 172.0
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 120.00
Pauling Negativity Number: 2.02
First Ionizing Energy (kJ/mol): 702.9
Oxidation States: 5, 3
Electronic Configuration: [Xe] 4f14 5d10 6s2 6p3
Lattice Structure: Rhombohedral (RHL)
Lattice Constant (): 4.750
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 2.25
Brinell Hardness [/MN m-2]: 94.2

Note: Bismuth is a soft metal, but brittle, and not difficult to prepare. However, retaining bismuth particles in free machining steels is difficult. 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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