It is the energy required to remove electron(s) from a gaseous atom to form an ion. It increases along the period but decreases down the group due to an increase in the screening effect.
It is the energy change that occurs when electron(s) is gained by a gaseous atom to form a negative ion. It increases long the period but decreases down the group.
Note: Electronegativity is the same as electron affinity in the periodic trend.
Atomic radius is the distance between the centre of the atom to the outermost shell of that atom. It decreases along the period but increases down the group.
Effective nuclear charge
It is the pull, which the nucleus exerts on the shells of electrons outside the nucleus. It increases along the period but decreases down the group.
It is the tendency whereby atoms (usually metallic atoms) lose electron(s) to be positively charged. It increases down the group but decreases across the period.