53 Explain, in terms of electrons, why the radius of a potassium atom is larger than the radius of a potassium ion in the ground state.

The potassium ion is K^1+, which contains less electrons than the neutral atom. The ion is an cation, and cations always have a smaller radius than the neutral atom due to less electrons that cause increased effective nuclear charge. This creates more coulombic attraction between the nucleus and the remaining electrons in the p orbital. The attraction towards the nucleus makes the radius of the cation decrease, and the cation is smaller than the parent atom