Subject: Inorganic Chemistry · Chapter: Chemical Bonding · Topic: Chemical Bonding – General · Exam: CSIR-NET DEC 2013 · Marks: 2 · Difficulty: Easy
The energy of 2 s and 2 p orbitals is the same for
(a)Li
(b)$\mathrm{Li^{2+}}$
(c)$\mathrm{Be}^{2+}$
(d)$\mathrm{H}^{-}$
Answer
Answer (as printed): B
Explanation
$\mathrm{Li} = 1s^{2}\,2s^{1}\,2p^{0}$$\mathrm{Li^{2+}} = 1s^{1}\,2s^{0}\,2p^{0}$ (hydrogen like)$\mathrm{Be^{2+}} = 1s^{2}\,2s^{0}\,2p^{0}$$\mathrm{H^{-}} = 1s^{2}\,2s^{0}\,2p^{0}$Li has one electron in 2s and no electron in 2p hence the energies of 2s and 2p orbitals will be different.$\mathrm{Li^{2+}}$ has only one electron in $1s^{1}$ hence will have no screening effectTherefore, 2s and 2p will have same energies.