Question

Element X is a metal with a valency 2. Element Y is a non-metal with a valency 3.
(a) Write equations to show how X and Y form ions.
(b) If Y is a diatomic gas, write the equation for the direct combination of X and Y to form a compound.

Answer 1

(a) Element X will lose its valence electrons to form a cation as shown below:

X → X²⁺ + 2e^-

Element Y will gain three electrons to form an anion as shown below:

Y + 3e^- → Y^3-

(b) One atom of Y gain 3 electrons therefore two atoms of Y will gain 6 electrons which can be represented as:

$Y_2+6e^{-}\to Y_2^{3-}$

To balance these 6 electrons 3 atoms of X will be taken.

So, the direct combination of elements X and Y can be represented by the following chemical equation:

3X + Y₂ $\to$ X₃Y₂