Potassium

Symbol: K
Atomic Number: 19
Atomic Weight: 39.0983
Element Classification: Alkali Metal
Discovered By: Sir Humphrey Davy
Discovery Date: 1807 (England)
Name Origin: English: pot ash; symbol from Latin: kalium, (alkali).

Density (g/cc): 0.856
Melting Point (K): 336.8
Boiling Point (K): 1047
Appearance: Soft, waxy, silvery-white metal
Atomic Radius (pm): 235
Atomic Volume (cc/mol): 45.3
Covalent Radius (pm): 203
Ionic Radius: 133 (+1e)
Specific Heat (@20C J/g mol): 0.753
Fusion Heat (kJ/mol): 102.5
Evaporation Heat (kJ/mol): 2.33
Thermal Conductivity (@25C W/m K):
Debye Temperature (K): 100.00
Pauling Negativity Number: 0.82
First Ionizing Energy (kJ/mol): 418.5
Oxidation States: 1
Electronic Configuration: [Ar] 4s1
Lattice Structure: Body-Centered Cubic (BCC)
Lattice Constant (): 5.230
Lattice C/A Ratio: n/a

Mineral Hardness [no units]: 0.4
Brinell Hardness [/MN m-2]: 0.363

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