chemistry

ELECTRONIC THEORY OF VALENCY

·         This was proposed by Kossel and Lewis.

·         This theory explains how and why the bonds are formed.

·         Valence electrons are responsible for bonding process.

·         Inert gases have ns²np⁶configuration but, Helium has 1s². Thus, all inert gases have octet and helium has duplet configuration.

·         Noble gases are chemically inert and will not take part in bonding because they are stable due to octet configuration in the valence shell.

·         Atoms of all other elements contain less than 8 electrons in valence shell.

§  ∴These elements are chemically reactive and take part in chemical reactions to become stable by attaining octet configuration.

·         Attaining octet configuration in the valence shell is called octet rule or octet theory.

·         Some elements may become stable by attaining duplet configuration e.g. H, Li, Be.

·         Octet configuration can be achieved by loosing or gaining or mutual sharing of electrons.

§  As per this theory, core electrons will not take part in bonding. Atom - Valence = Core