Question

question
these two elements, shown in the picture below, form an ionic bond.
based on your knowledge of the groups of the periodic table, what is the
correct formula unit of the compound formed from these two elements?
a) xy₂
b) xy
c) x₂y
d) xy₆

Explanation:

Step1: Determine the valency of X and Y

• X has 1 valence electron (from the dot - structure). So, the valency of X is \(+ 1\) (it will lose 1 electron to achieve a stable configuration).
• Y has 6 valence electrons. So, the valency of Y is \(- 2\) (it will gain 2 electrons to achieve a stable configuration).

Step2: Use the criss - cross method

• For an ionic compound formed between \(X^{+}\) and \(Y^{2 -}\), using the criss - cross method (where we swap the absolute values of the valencies as sub - scripts).
• The formula of the compound is \(X_{2}Y\)

Answer:

C) \(X_{2}Y\)