Question

If the number of protons in one atom of an element Y is 20, then the number of electrons in its ion Y²⁺ will be ______.

Options

• 20

• 19

• 18

• 16

Answer 1

If the number of protons in one atom of an element Y is 20, then the number of electrons in its ion Y²⁺ will be 18.

Explanation:

An atom with 20 protons has an atomic number of 20, meaning its neutral state contains 20 electrons. The 2+ charge on the Y²⁺ ion indicates that the atom has lost 2 negatively charged valence electrons to achieve a stable outer shell. Subtracting these 2 lost electrons from the original 20 leaves the ion with a total of 18 electrons.