Test: Mendeleev's periodic table, Modern periodic table - JEE MCQ

The cause of periodicity of properties of elements is due to the repetition of similar electronic configuration of their atoms in the outermost energy shell after certain regular interval.

The tendency of an atom in a molecule to attract the shared pair of electrons towards itself is called its electronegativity.
Electronegativity is a dimensionless property since it is only a tendency. It only indicates the net result of the tendencies of different elements to attract the bond forming electron pair.

The electronic configuration of Na,Ne,Mg and Al after the removal of an electron is as

The ionisation energy decreases as the size of the atom/ion increases. Further ionisation energy increases with increase in nuclear charge.
Since, Na⁺ gives a stable electronic configuration hence its IE₂ is highest among the given species and therefore the correct order of their IE₂ is
Mg < Al < Ne < Na

Electronic configuration of 
The maximum covalency of any element is found by counting the number of covalent and coordinate bonds that it can form.
So, the maximum covalency of element having is 6.
Since, it has 3 electrons in the valence shell, its highest oxidation state is +3.

Electronegativity values of given elements are as follows:

IP increases along the period. But IP of . Further IP of because atoms with fully or partly filled orbitals are most stable and hence have high ionisation energy.

The first ionization enthalpy generally decreases down the group in Group 13 of the periodic table due to the increasing atomic size, which leads to easier removal of the outermost electron. So, the order B > Ga > Tl follows this trend.

I.E. E.A.

Electronegativity