definition of?

Question

first molar ionization ethalpy
effevtive nuclear charge
electronegativity

Answer 1

electronegativity is the ability of the bonded pair of atoms to attract the bonded pair of electrons towards itself.
effective nuclear charge is the total charge present on the nucleus.

Answer 2

1. The molar enthaply change accompanying the removal of an electron from a gas-phase atom (or ion).

2. The nuclear charge, Z, is the charge of the nucleus. The effective nuclear charge, Zeff, is the amount of positive charge on the nucleus perceived by an electron. Electrons intervening between the nucleus and an outer electron are said to shield or screen the outer electron from the nucleus so that the outer electron does not experience the full nuclear charge.

3. 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.

Answer 3

Effective nuclear charge may well be a useful concept, in order to try to understand the relationship between the nucleus and the electrons surrounding it, but don't quote it in examination answers - refer to actual nuclear charge, screening and distance of the electrons from the nucleus instead.