Question

the table below lists information about some diatomic molecules or molecular ions. for each molecule in the table: first, decide if the molecule is stable or not. then, if your answer to this question is \yes\: decide whether the molecule would be diamagnetic or paramagnetic. calculate the molecules bond order.

Explanation:

Step1: Recall MO - theory concepts

The molecular orbital (MO) theory uses the formula for bond - order \(BO=\frac{1}{2}(N_b - N_a)\), where \(N_b\) is the number of bonding electrons and \(N_a\) is the number of antibonding electrons. A molecule is stable if \(BO>0\), diamagnetic if all electrons are paired, and paramagnetic if there are unpaired electrons.

Step2: Analyze \(C_2\)

The electron - configuration of \(C\) is \(1s^22s^22p^2\). In \(C_2\), the total number of electrons is \(12\). The MO electron - configuration is \(\sigma_{1s}^2\sigma_{1s}^*^2\sigma_{2s}^2\sigma_{2s}^*^2\pi_{2p}^4\). \(N_b = 8\), \(N_a=4\), so \(BO=\frac{1}{2}(8 - 4)=2\). Since all electrons are paired, it is diamagnetic.

Step3: Analyze \(F_2^-\)

The electron - configuration of \(F\) is \(1s^22s^22p^5\). In \(F_2^-\), the total number of electrons is \(19\). The MO electron - configuration: \(\sigma_{1s}^2\sigma_{1s}^*^2\sigma_{2s}^2\sigma_{2s}^*^2\sigma_{2p}^2\pi_{2p}^4\pi_{2p}^*^4\sigma_{2p}^*^1\). \(N_b = 8\), \(N_a = 9\), so \(BO=\frac{1}{2}(8 - 9)=0.5\). Since there is an unpaired electron (\(\sigma_{2p}^*^1\)), it is paramagnetic.

Step4: Analyze \(H_2\)

The electron - configuration of \(H\) is \(1s^1\). In \(H_2\), the total number of electrons is \(2\). The MO electron - configuration is \(\sigma_{1s}^2\). \(N_b = 2\), \(N_a = 0\), so \(BO=\frac{1}{2}(2 - 0)=1\). Since all electrons are paired, it is diamagnetic.

Answer:

molecule	stable?	diamagnetic or paramagnetic?	bond order
\(F_2^-\)	yes	paramagnetic	0.5
\(H_2\)	yes	diamagnetic	1