Question

What is the highest valency?

Answer 1

Hint:Valency is defined as the number of electrons gained or lost by an atom to attain stability and acquire noble gas configuration. It is the capacity of an atom to combine with another atom. If the number of electrons in the outermost shell is in between one and four, then the compound will have positive valency.

Complete step-by-step answer:Valence electrons are the electrons that are present in the outermost shell of an atom. Valence electrons help in determining the valency of an atom.
The valency of an element that belongs to s-block and p-block of the periodic table can be calculated by the number of valence electrons present in an atom and eight minus the number of valence electrons.
The valency of d-block and f-block of an element is calculated not only on the basis of valence electrons but also on d and f orbital electrons. The general valency of d block and f block elements are two and three.
Valency depends upon the number of valence electrons present in an atom. If an atom has three electrons in an octet, it has to give them away so as to attain an octet. If an atom has five electrons, it has to gain three electrons to attain an octet. If an atom has four electrons, then it needs or gives four electrons to attain octet. Therefore the highest valency of an element is four.

Note:It is to note that, as we move down the group, the number of valence electrons does not change. Therefore, all elements in a group have the same valency but as we move from left to right in a period, valency firstly increases from one to four and then reduces to zero.