Question

What do you understand by valency of an element? Is it possible to state the metallic and the non metallic character of an element from their valency?
Can an element show varaible valency. Explain why? [5 MARKS]

Answer 1

Definition: 1 Mark
Explanation : 2 marks each

The valency is the number of the electrons that an atom gains , loses or even shares during a chemical reaction . In other words, the valency is the number of electrons that an atom needs to gain or lose on order to achieve a noble gas electronic configuration .

Yes ,it is possible to state the metallic and the non metallic character of an element by observing their valencies. Those elements whose valencies range from 1 to 3 are metals. They donate electrons from their outermost shell in order to gain a stable octet. They become positively charged ions called cations (cathode seeking ions) as the n(protons) become greater than the n(electrons) after electrons have been donated.

The property of elements to show valencies of more than two forms are called metals with variable valencies.
Some elements show variable valency because of the different electronic configurations. An atom of an element
can sometimes lose more electrons than are present in its valence shell i.e. loss from the penultimate shell because its electrons are in a highly excited state. These are the elements that exhibit more than 1 or variable valency.