# Question #d9e98

Dec 3, 2017

An atom can lose its electron or gain electron from atoms of other elements. Electropositve metals like that in Group 1 and Group 2 of periodic table can readily donate or lose electrons.

Alkali metals{Gr.1} on the account of low ionisation energy have a stong tendency to lose their single valence electron(ns1) and change to unipositive ion . Na$\rightarrow$Na+ + 1e-

By losing the solitary valence electron , alkali metals acquire the stable configuration of nearest noble gas . These elements have strong tendeny to form M+ ion and thus exhibit an oxidation state of +1 thus forming positive valency.

Where as Gr.17 elements readily accept electrons{X + 1e-$\rightarrow$ X-}.
This is on the account of high electron gain enthalpy. They have very stong tendency to accept electons and form anions{X-} thus forming negative valency as by accepting an electron they can attain the nearest stable noble gas configuration.

Generally elements with low Ionisation Enthalpy shows positive valency and elements with high negative electron gain enthalpy shows negative valency ,