Question

Right or wrong sentence.

The size of an atom depends on the number of compound electrons.

Answer 1

The given sentence is wrong.

Explanation:

The size of an atom is given by its atomic radius and depends mainly on the number of electron shells (distance of the outermost shell from the nucleus) and the effective nuclear charge. Across a period, increased nuclear charge pulls electrons closer and decreases size.

Going down a group, the addition of a new electron shell increases the distance to the outer electrons and so increases atomic size; the phrase “compound electrons” is not standard. Say “electrons/shells” or “valence electrons” instead.