Q.Explain the diagonal relationship.
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Start your 14-day free trial to unlock the full solution →The question asks us to explain the diagonal relationship in the periodic table.
Some second-period elements resemble the element diagonally below-and-to-the-right of them (LiMg, BeAl, B~Si) because those pairs have similar charge/radius ratios (polarising power) and electronegativity.
As we move across a period, atomic size decreases and electronegativity/polarising power increases; as we move down a group, size increases and these properties decrease. When both effects are combined by moving diagonally (one step across and one step down), they tend to cancel, so an element and the one diagonally placed to it end up with very similar charge/size ratio (ionic potential), similar polarising power and similar electronegativity. As a result they show similar chemical behaviour.
The well-known diagonally related pairs are:
- Lithium and Magnesium (Li~Mg)
- Beryllium and Aluminium (Be~Al)
- Boron and Silicon (B~Si) …
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