Alkali metals have a valency of +1. With only a single covalent bond, the metals are weakly bound. The metals are soft, so that they can be cut with a knife. They have low density and lithium, sodium and potassium are all light enough to float on water. They react with non-metals to form salts. These salts are white, crystalline and soluble in water. Under conditions where alkali metals react with water the result is an alkaline solution. They have a characteristic reaction with oxygen such that oxygen will combine with lithium to form lithium oxide (Li2O).
|Element||Atomic number||Atomic weight||Boiling point||Density||Heat fusion||Heat vapour||Melting point||Specific heat capacity||Thermal conductivity|
|Caesium||55||132.9||963.16° K||1900 kg/m³||2.09 kJ/mol||68.26 kJ/mol||301.86° K||5.3 W/m/K|
|Hydrogen||1||1.01||20.46° K||71 kg/m³||13.96° K|
|Rubidium||37||85.47||961.16° K||1530 kg/m³||2.3 kJ/mol||75.8 kJ/mol||312.06° K||8 W/m/K|
|Sodium||11||22.99||1165.16° K||970 kg/m³||2.6 kJ/mol||101.01 kJ/mol||370.96° K||134 J/kg/K||21.8 W/m/K|