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What is the valency of ammonia and ammonium ions?
The valency of ammonia NH3 as a compound has a valency of 0 due to the completion of octet in its outermost orbit. Ammonium ion has the chemical formula of NH4+ having valency of +1 in the form of a positive ion.
Valency refers to the number of electrons that are gained or lost by an atom in order to complete its outermost shell. By completing their outer shell, or octet (8 electrons in the outermost shell), the atoms become stable.
The electron numbers of ammonia and ammonium are not the same as the total amount of electrons present in the outermost orbit of the two, which is why their valencies differ. You should also keep in mind that the quantity of electrons present in an atom’s outermost orbit determines how many electrons this compound can lose or gain.
Ammonia has the formula NH3 which makes it a nitrogen-hydrogen compound. It is a colourless gas that has a pungent odour with stable binary hydride and the simplest pnictogen hydride. It’s a nitrogenous waste that helps terrestrial organisms achieve their nutritional needs by acting as a precursor to food and fertilisers.
It has zero valency because it follows the octet rule (5 + 3 = 8 electrons in the outermost orbit) which results in an oxidation number of zero. This shows it is a very stable compound that cannot lose or gain any more electrons.
An ammonium ion is generated when a neutral ammonia molecule, NH3, is protonated or takes on an extra positively charged hydrogen atom. The chemical reaction is:
NH3+H+→NH4+
When it comes to the ammonium ion, there are a total of 8 valence electrons. Although nitrogen contains five valence electrons and each hydrogen has one, the overall positive charge suggests that one electron has been lost, therefore 5 + 4 (1)-1 = 8 . As one electron has been lost it has a valency of +1.
