Difference between alkaline earth metals and alkali metals

Both alkaline earth metals and alkali metals are s – block elements as the last electron enters the ns – orbital. They resemble with each other in some respects but still there are certain dissimilarities in their properties on account of different number of electrons in the valency shell, smaller atomic radii, high ionization potential, higher electro negativity etc.



Alkaline earth metals

Alkali metals


Electronic configuration

Two electrons are present in the valency shall. The configuration is ns2 (bivalent)

One electron is present in the valency shell. The configuration is ns1 (monovalent) more electropositive






Electropositive nature

Less electropositive

More electropositive



Weak bases, less soluble and decompose on heating.

Strong bases, highly soluble and stable towards heat.



These are not known in free state. Exist only in solution.

These are known in solid state.



Insoluble in water. Decompose on heating.

Soluble in water. Do not decompose on heating (LiCO3 is an exception)


Action of nitrogen

Directly combine with nitrogen and form nitrides

Do not directly combine with nitrogen except lithium


Action of carbon

Directly combine with carbon and form carbides

Do not directly combine with carbon



Decompose on heating evolving a mixture of NO2 and oxygen

Decompose on heating evolving only oxygen


Solubility of salts

Sulphates, phosphates fluorides, chromates, oxalates etc are insoluble in water

Sulphates, phosphates, fluorides, chromates, oxides etc are soluble in water.


Physical properties

Comparatively harder. High melting points. Diamagnetic.

Soft, low melting points paramagnetic.


Hydration of compounds

The compounds are extensively hydrated. MgCl2.6H2O, CaCl2.6H2O, BaCl2.2H2O are hydrated chlorides.

The compounds are less hydrated. NaCl, KCl, RbCl form non – hydrated chlorides


Reducing power

Weaker as ionization potential values are high and oxidation potential values are low.

Stronger as ionization potential values are low and oxidation potential values are high.

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