Trends in the periodic table

Half-the distance between two bonded atoms

Energy required to remove one mole of electrons from one mole of gaseous atoms

This is a measure of the attraction an atom of an element has for bonding electrons

The covalent radius increases going down the group and decreases going across the period

It increases due to the increasing number of electron shells making the atom bigger

The 1st ionisation energy decreases going down the group and increases going across the period

It decreases due to the increasing nuclear charge pulling the electrons closer to the nucleus

It decreases due to the increasing number of electron shells making the atom bigger and increased shielding as this means that the outer electrons are less strongly held

It increases due to the increasing nuclear charge pulling electrons closer to the nucleus and the smaller covalent radius meaning the outer electrons are more strongly held

Electronegativity decreases going down the group and increases going across the period

It decreases due to the increasing number of electron shells making the atom bigger and the increased shielding resulting in the outer electrons being less tightly held

It increases due to the increasing nuclear charge pulling the electrons closer in to the nucleus and the smaller covalent radius meaning that the outer electrons are more tightly held