Potassium or kalium

Symbol: K
Atomic number: 19
Category: alkali metals
Group: 1
Period: 4
Block: s
Atomic weight: 39.0983 g/mol
Electrons per shell: 2, 8, 8, 1
CAS number: 7440-09-7
Phase: solid
Density: 0.89 kg/l (near room temperature)
Melting point: 336.53 K (63.38C, 146.08F)
Boiling point: 1032 K (759C, 1398F)
Crystal structure: cubic body centered
Oxidation states: 1
Electronegativity: 0.82 (Pauling scale)
Name's origin (potassium): potash
Name's meaning: potassium was first isolated from potash
Name's origin (kalium): al-qaly
Name's meaning: the calcined ashes, referring to the original source of alkaline substance
Facts:
- the second lightest elemental metal after lithium
- floats on water
- can be cut with a knife
- like other alkali metals it reacts violently with water, forming hydrogen gas