Potassium (K)

From Wikipedia, the free encyclopediaPotassium is a chemical element with symbol K (derived from Neo-Latin, kalium) and atomic number 19. It was first isolated from potash, the ashes of plants, from which its name is derived. In the Periodic table, potassium is one of seven elements in column (group) 1 (alkali metals):they all have a single valence electron in their outer electron shell, which they readily give up to create an atom with a positive charge - a cation, and combine with anions to form salts.

Potassium in the periodic table

SymbolK
Atomic number19
Group1
Period4
Blocks
Element categoryAlkali Metal

Physical properties

Phase at STPSolid
Density0.862 g/cm3
Atomic weight39.0983 u
Melting point336.7 K
63.55 °C
146.39 °F
Boiling point1032 K
758.85 °C
1397.93 °F

Atomära egenskaper

Electronegativity (Pauling Scale)0.82
Electron affinity48.383 kJ/mol
Ionization energies
1418.8 kJ/mol
2 3052 kJ/mol
3 4420 kJ/mol
4 5877 kJ/mol
5 7975 kJ/mol
6 9590 kJ/mol
7 11343 kJ/mol
8 14944 kJ/mol
9 16963.7 kJ/mol
10 48610 kJ/mol
11 54490 kJ/mol
12 60730 kJ/mol
13 68950 kJ/mol
14 75900 kJ/mol
15 83080 kJ/mol
16 93400 kJ/mol
17 99710 kJ/mol
18 444880 kJ/mol
19 476063 kJ/mol

Electron configuration

Electron configuration1s2 2s2 2p6 3s2 3p6 4s1
Electrons per shell2, 8, 8, 1

History

Discovered1807
Discovered byHumphry Davy