Question

What is Electronegativity?
Define ionisation Enthalpy.

Answer 1

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. The Pauling scale is the most commonly used. Fluorine (the most electronegative element) is assigned a value of 4.0, and values range down to caesium and francium which are the least electronegative at 0.7.
Ionization Energy. Ionization energy is the quantity of energy that an isolated, gaseous atom in the ground electronic state must absorb to discharge an electron, resulting in a cation. This energy is usually expressed in kJ/mol, or the amount of energy it takes for all the atoms in a mole to lose one electron each.

Answer 2

electronegativity - the tendency of an atom to attract shared paired of electrons towards itself.

ionization enthalpy - amount of energy required by an isolated atom to lose electrons in its ground state.