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. molecule stable? diamagnetic or paramagnetic? bond order n₂ yes diamagnetic no paramagnetic li₂ yes diamagnetic no paramagnetic he₂ yes diamagnetic no paramagnetic

Explanation:

Step1: Recall molecular - orbital theory for $N_2$

Nitrogen has 7 electrons. In $N_2$, the total number of electrons is 14. The molecular - orbital configuration is $(\sigma_{1s})^2(\sigma_{1s}^*)^2(\sigma_{2s})^2(\sigma_{2s}^*)^2(\pi_{2p_x})^2(\pi_{2p_y})^2(\sigma_{2p_z})^2$.

Step2: Calculate bond order of $N_2$

The bond - order formula is $BO=\frac{1}{2}(N_b - N_{a})$, where $N_b$ is the number of bonding electrons and $N_{a}$ is the number of antibonding electrons. For $N_2$, $N_b = 10$ and $N_{a}=4$. So, $BO=\frac{1}{2}(10 - 4)=3$. Since all electrons are paired, it is diamagnetic and stable.

Step3: Recall molecular - orbital theory for $Li_2$

Lithium has 3 electrons. In $Li_2$, the total number of electrons is 6. The molecular - orbital configuration is $(\sigma_{1s})^2(\sigma_{1s}^*)^2(\sigma_{2s})^2$.

Step4: Calculate bond order of $Li_2$

Using the bond - order formula $BO=\frac{1}{2}(N_b - N_{a})$, with $N_b = 4$ and $N_{a}=2$, we get $BO=\frac{1}{2}(4 - 2)=1$. Since all electrons are paired, it is diamagnetic and stable.

Step5: Recall molecular - orbital theory for $He_2$

Helium has 2 electrons. In $He_2$, the total number of electrons is 4. The molecular - orbital configuration is $(\sigma_{1s})^2(\sigma_{1s}^*)^2$.

Step6: Calculate bond order of $He_2$

Using the bond - order formula $BO=\frac{1}{2}(N_b - N_{a})$, with $N_b = 2$ and $N_{a}=2$, we get $BO=\frac{1}{2}(2 - 2)=0$. It is diamagnetic but unstable.

Answer:

molecule	stable?	diamagnetic or paramagnetic?	bond order
$Li_2$	yes	diamagnetic	1
$He_2$	no	diamagnetic	0