Atomic and Ionic Radii Quiz | AS Chemistry

Answer: c) The increasing nuclear charge pulls the electrons closer to the nucleus, while the shielding effect remains relatively constant because the number of inner electron shells doesn't change.

d) Mg²⁺ has the smallest radius because it has the largest nuclear charge (+12), pulling its electrons closest to the nucleus.

Answer: c) Anions gain electrons, increasing electron-electron repulsion and thus the radius.

Answer: b) New electron shells are added, increasing the distance between the nucleus and the outermost electrons.

a) Li and Na have the largest difference in atomic radius because Na is much larger than Li due to being in the next period down.

Answer: b) Inner shell electrons shield the outer electrons from the full nuclear charge.

Answer: b) These are isoelectronic. Cl⁻ has the fewest protons, therefore the least nuclear attraction, and so the largest radius. Ca²⁺ has the most protons and the smallest radius.

Answer: b) Iodine is further down the halogen group than fluorine, meaning it has more electron shells, leading to a larger atomic radius.

b) Al³⁺ < Mg²⁺ < Na⁺ < O²⁻

• Al³⁺ (smallest): Highest nuclear charge (+13), strongest pull on electrons.
• Mg²⁺: Weaker pull than Al³⁺, but still strong.
• Na⁺: Weaker attraction than Mg²⁺.
• F⁻: More electrons relative to protons, larger size.
• O²⁻ (largest): Least nuclear attraction per electron, largest radius.