Question

Based on the group valency of elements state the formula for the following giving justification for Compounds formed when an element of group 2 combines with an element of group 17.

Answer 1

Valency — the chemical combining capacity of an element is considered valency

• The word "valence" was described in 1425 from the Latin word valentia, which means strength or capacity.
• It depends upon the outermost shell electron
• if in its outermost shell has 1,2,3 e^- then their valency is 1,2,3 respectively
• if in its outermost shell has 5,6,7,8, e^- then their valency is 3,2,1,0 respectively
• valency of the first group element is 1 because having only one e^- in their outermost shell
• valency of the second group element is 2 because having only two e^- in their outermost shell

Based on the group valency of elements states the formula are:

• A compound is formed when an element, A of group 2 combines with an element, B of group seventeen.
• The valency of group 2 elements is 2 and that of group 17 is 1.
• Thus, two elements of group 17 are required to combine with group 2 elements.

For example, MgX₂ or MgCl2, CaX₂ or CaCl₂, etc