Question

How do you get the valency of a basic radical from its formula? Explain with an example.​

Answer 1

Answer:

Count how many hydrogen atoms are in the formula. This is the valency of the radical. For example, H2SO4 has two hydrogen atoms, so the valency of sulfate is two. Because sulfate can bond with two positive hydrogen atom, its valency is the opposite charge and often expressed as 2-.

Answer 2

The valency of a basic radical from its formula is determined by the cross-valency method.

• In the cross-valency or criss-cross method, the numerical value of the ion charge of the two atoms are crossed over which becomes the subscript of the other ion.
• The number of atoms bonded with other elements determines another's valency.
• An example can be given of a compound aluminium chloride which has the formula $AlCl_{3}$.
• The number of an aluminium atom is one and the chlorine atoms are three.
• Thus, the valency has to be cross-valenced, and the valency of aluminium becomes 3 and that of chlorine becomes 1.