Q5 · CSIR NET Chemistry, December 2013
Paper: CSIR NET December 2013 · Subject: Inorganic Chemistry · Chapter: Chemical Bonding · Topic: Chemical Bonding – General · Marks: 2 · Difficulty: Easy
The energy of 2s and 2p orbitals is the same for
(a)Li
(b)$\mathrm{Li^{+2}}$
(c)$\mathrm{Be^{+2}}$
(d)$\mathrm{H^{-}}$
Answer
Answer (as printed): B
Explanation
Li = 1s2 2s1 2p0 +2 Li 1s1 2s0 2p0 (hydrogen like) +2 Be = 1s2 2s0 2p0 - H = 1s2 2s0 2p0 Li has one electron in 2s and no electron in 2p hence the energies of 2s and 2p orbitals will be different. Li+2 has only one electron in 1s1 hence will have no screening effect Therefore, 2s and 2p will have same energies.
Explanation as extracted from the printed page; notation may be imperfect.
Study loop for Chemical Bonding