Which property increases down a group and to the left on the periodic table?

Which property increases down a group and to the left on the periodic table?

• A. Ionization Energy
• B. Atomic Radius
• C. Electron Affinity
• D. Electronegativity

Answer: (B)

Atomic radius describes how large an atom is. It increases down a group because each step down adds a new electron shell, pushing outer electrons farther from the nucleus and increasing shielding. It also increases as you move to the left across a period because there are fewer protons pulling on the same outer electrons, so the effective nuclear pull is weaker and the outer electrons aren’t held as tightly, making the atom larger. This combination—larger size with added shells down a column and weaker pull to the left across a row—is why this property grows both down a group and to the left. Other properties don’t follow that pattern: ionization energy generally decreases down a group, and electron affinity and electronegativity also tend to decrease down a group, so they don’t increase in both directions.

Atomic radius describes how large an atom is. It increases down a group because each step down adds a new electron shell, pushing outer electrons farther from the nucleus and increasing shielding. It also increases as you move to the left across a period because there are fewer protons pulling on the same outer electrons, so the effective nuclear pull is weaker and the outer electrons aren’t held as tightly, making the atom larger. This combination—larger size with added shells down a column and weaker pull to the left across a row—is why this property grows both down a group and to the left. Other properties don’t follow that pattern: ionization energy generally decreases down a group, and electron affinity and electronegativity also tend to decrease down a group, so they don’t increase in both directions.