Question

Define valency. Give valency to copper and iron?

Answer 1

Valency:

• The combining capacity of the atom of an element is called its valency.
• It is always a whole number.
• Valency varies from 1 to 8.
• Valency is always positive.
• An element with a valency is one called monovalent, with two called divalent.
• The valency of noble gases is zero.

Variable valency

• Variable valency is the power of elements to represent different valencies in different compounds.
• Variable valency doesn't have a fixed pattern.
• To get the variable valency of any element, its electronic configuration is necessary.
• Some elements represent variable valency by reason of different electronic configurations. It happens due to the loss of electrons from one shell to another.
• The reason for losing extra electrons is a matter of specific electrons.
• The process of jumping electrons from 1 shell to another is due to the presence of vacant orbits in the same subshells.

Valency of copper:

• The atomic number of copper is 29.
• The electronic configuration of the element is- 1s²2s²2p⁶3s²3p⁶4s¹3d¹⁰.
• Therefore, the valency of copper is 2 and1.

Valency of Iron:

• The atomic number of iron is 26.
• The electronic configuration of the element is- 1s²2s²2p⁶3s²3p⁶4s²3d⁶.
• Therefore, the valency of iron is 2 and 3.

Iron and copper have variable valency because they show involvement of vacant orbitals and electrons from outermost and penultimate shells are involved in the reaction.