What is the difference between alkali metals and alkali earth metals
- Nature of the elements: alkali metals are soft in nature when compared to alkaline earth metals.
- Oxidation state: alkali earth metals exhibit an oxidation state of +1. Alkaline earth metals which have two electrons in the outermost s-orbital exhibit an oxidation state of +2.
- Reactivity with nitrogen: alkali metals do not react with nitrogen directly. Alkaline earth metals combine with nitrogen directly and form nitrides.
- Reaction with ammonia: alkali metals react with ammonia forming amides. Alkaline earth metals react with ammonia at low temperature forming hexamines M (NH3) 6
- Stability of the carbonates: carbonates formed by alkali metals are very stable compared to those formed by alkaline earth metals. Carbonates of alkaline earth metals decompose easily upon heating.
- Decomposition of nitrates: nitrates formed by alkali metals decompose evolving oxygen. NO2 is liberated by decomposition of nitrates formed by alkaline earth metals.
2KNO3 ? 2KNO2 + O2
2Ba (NO3)2 ? 2BaO + 4NO2 + O2
- Solubility of sulphates: Sulphates formed by alkali metals are highly soluble and form alums very easily. Sulphates of alkaline earth metals are sparingly soluble and do not form alums.
- Solubility of bicarbonates: bicarbonates of alkali metals are less soluble than their corresponding carbonates. But, the bicarbonates of alkaline earth metals are more soluble than their corresponding carbonates.
- Solubility of fluorides, carbonates, phosphates and oxalates: fluorides, carbonates, phosphates and oxalates of alkali metals are soluble. While those of alkaline earth metals are insoluble.