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# Discuss the pattern of variation in the oxidation states of B to Ti.

11.1     Discuss the pattern of variation in the oxidation states of
$(i)\; B\; to\; Tl$

These elements belong to group 13 of the general electronic configuration$ns^2,\ np^1$. These elements have three valence electrons, therefore, they can exhibit a maximum only +3 oxidation state. Boron shows only +3 oxidation state but other elements also show +1 oxidation state.  On moving down the group from$B\; to\; Tl$, its stability increases due to inert pair effect. After removal of the last electron from p- orbital, the remaining two electrons behave like inert gases and don't take part in bonding. They are strongly attracted by the nucleus. This reluctance of the s- electron pair to take part in bond formation is called inert pair effect.