Trends

Electronegativity

The tendency of an atom to attract bonding electrons towards itself.

Ionization Energy

The energy required to remove an electron from an atom.

Atomic Radius

The distance from the nucleus to the outermost electron shell of an atom.

Across a Period (Left to Right) - Electronegativity

Increases due to higher nuclear charge attracting electrons more strongly.

Across a Period (Left to Right) - Ionization Energy

Increases as electrons are held more tightly by the increasing nuclear charge.

Across a Period (Left to Right) - Atomic Radius

Decreases because the increased nuclear charge pulls the electron cloud closer.

Down a Group (Top to Bottom) - Electronegativity

Decreases as valence electrons experience reduced effective nuclear charge.

Down a Group (Top to Bottom) - Ionization Energy

Decreases because outer electrons are more shielded and farther from the nucleus.

Down a Group (Top to Bottom) - Atomic Radius

Increases due to additional electron shells leading to a larger atomic radius.