Electronegativity A measure of the ability of an atom that is bonded to another atom to attract electrons to itself. Trend: Increases from left to right Exclude Noble Gases Decrease top to bottom Electronegativity

Ionization Energy The energy required to remove an electron from a gaseous atom when the atom is in its ground state. Trend: Increases from left to right Decrease from top to bottom

Atomic Radius An estimate of the size of an atom. Trend: Decrease from left to right Increase from top to bottom

Ionic Radius How does the size of an atom change when electrons are added or removed? As an Atom loses 1 or more electrons (becomes positive), it loses a layer therefore, its radius decreases.

Ionic Radius How does the size of an atom change when electrons are added or removed? As an Atom gains 1 or more electrons (negative), it fills its valence layer, therefore, its radius increases.

Ionic Radius Trend increases as move down the periodic table. Lose electron – smaller Gain electron - bigger