Metallic Character
The tendency of an element to lose electrons and display typical metallic properties such as lustre, malleability and conductivity.
Unit
Dimensionless
In depth
Metallic character depends inversely on ionisation energy, so it decreases across a period as effective nuclear charge grows and increases down a group as the valence shell moves further from the nucleus. This is why the boundary between metals and non-metals runs diagonally through the p-block.
Examples in the real world
Caesium is the most metallic stable element; within period 3, sodium is strongly metallic while chlorine is not at all.