CBSE Class 11-science Answered

's' block elements, (except helium) are those in which the valence-shell is the 'ns' orbital and where the last electron enters into the 's' orbital of the outer element. The general outer electronic configuration of such elements is either ns¹or ns². The 's' block elements belong to group 1 and 2 of the long form periodic table. They are situated on the left side of the table.

Characteristics

• The general outer electronic configurations of 's' block elements are ns^1-2 as all inner shells are already full.

• The 's' block elements are either all alkali metals like Li, Na, K, Rb, Cs and Fr, as in group 1 (having ns¹ outer electronic configuration) or alkaline Earth metals like Be, Mg, Ca, Sr, Ba and Ra, as in group 2 (having ns² outer electronic configurations).

• The 's' block metals are soft and have a low melting and boiling point.

• The metals are very active. They are highly electropositive and lose their valence electrons to form monovalent or divalent cation

• Being highly electropositive, these elements lose electrons readily and are strong reducing agents.

• The 's' block elements mostly form ionic compounds like NaCl, KCl, CaCl₂ etc