Question

For the electrons of oxygen atom, which of the following statements is correct?

• A. $Z_{eff}$ for an electron in a $2s$ orbital is the same as $Z_{eff}$ for an electron in a $2p$ orbital
• B. An electron in the $2s$ orbital has the same energy as an electron in the $2p$ orbital
• C. $Z_{eff}$ for an electron in Is orbital is the same as $Z_{eff}$ for an electron in a $2s$ orbital.
• D. The two electrons present in the $2s$ orbital have spin quantum numbers, $m_s$ but of opposite sign

Answer 1

Answer: (D)

(a) $Z_{eff}$ for an electron in a $2s$ orbital is greater than that in a $2p$ orbital ($s$ orbital is more tightly bound to the nucleus than $p$ orbital).
(b) Energy of $2s<2p$, lower the value of $n+l$, lower is the energy.
(c) $Z_{eff}$ for an electron in is orbital is greater than $Z_{eff}$ for an electron in a $2s$ orbital.
(d) The two electrons present in any orbital have spin quantum numbers with opposite sign (i.e., $m_s=+\frac{1}{2}$ and $-\frac{1}{2}$).