Question

Consider the following statements about first ionization energies:

Answer 1

Answer:

I,II, III

Explanation:

Firstly, the magnitude of nuclear charge affects the first ionization energy of an element. Hence,as effective nuclear charge increases, the attraction between the nucleus and the outermost electron increases and ionization energy consequently increases. Thus Mg has a higher first ionization energy than Be.

Secondly, oxygen has an electron configuration of 1s2 2s2 2p4 while nitrogen has an electron configuration of 1s2 2s2 2p3. Now, recall that extra energy is often associated with half filled orbitals hence nitrogen has a higher first ionization energy than oxygen. Furthermore, the addition of electron to an already half filled 2p orbital in oxygen (pairing) leads to inter electronic repulsion and drastic fall in first ionization energy. Therefore, as we move from nitrogen to oxygen in the periodic table, greater inter-electron repulsion between two electrons in the same p-orbital counter balances the increase in effective nuclear charge hence nitrogen has a greater first ionization energy than oxygen.

Lastly, the 3p orbital is far away from the nucleus hence we expect it to feel less of nuclear attraction than a 2p orbital. Hence the first ionization energy of Ar is less than that of Ne.