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
$be_2$	yes <br> no	diamagnetic <br> paramagnetic
$ne_2$	yes <br> no	diamagnetic <br> paramagnetic

Explanation:

Step1: Recall molecular - orbital theory

Molecular - orbital theory is used to determine stability, magnetic properties, and bond - order. 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.

Step2: Analyze $B_2$

The electron - configuration of $B$ is $1s^22s^22p^1$. For $B_2$, the molecular - orbital configuration is $(\sigma_{1s})^2(\sigma_{1s}^*)^2(\sigma_{2s})^2(\sigma_{2s}^*)^2(\pi_{2p_x})^1(\pi_{2p_y})^1$. $N_b = 6$, $N_a = 4$. $BO=\frac{1}{2}(6 - 4)=1$. Since $BO>0$, $B_2$ is stable. It has unpaired electrons, so it is paramagnetic.

Step3: Analyze $Be_2$

The electron - configuration of $Be$ is $1s^22s^2$. For $Be_2$, the molecular - orbital configuration is $(\sigma_{1s})^2(\sigma_{1s}^*)^2(\sigma_{2s})^2(\sigma_{2s}^*)^2$. $N_b = 4$, $N_a = 4$. $BO=\frac{1}{2}(4 - 4)=0$. Since $BO = 0$, $Be_2$ is unstable.

Step4: Analyze $Ne_2$

The electron - configuration of $Ne$ is $1s^22s^22p^6$. For $Ne_2$, the molecular - orbital configuration has a large number of antibonding electrons. $N_b = 8$, $N_a = 8$. $BO=\frac{1}{2}(8 - 8)=0$. Since $BO = 0$, $Ne_2$ is unstable.

Answer:

molecule	stable?	diamagnetic or paramagnetic?	bond order
$Be_2$	no	N/A (unstable)	0
$Ne_2$	no	N/A (unstable)	0