Question

Question: What molecular ions would you expect for the compound depicted in the ball-and-stick model?

Short answer

Answer

For the given compound, 162 and 164 molecular ions are expected.

Step-by-step solution

Identify the elements by analyzing the model

The tetravalent black ball symbolizes a carbon atom, the white ball symbolizes a hydrogen atom.

The red ball with only one bond, that is double the size of a carbon atom, must be a bromine atom.

Predicting the molecular ion

The molecular ion is predicted by calculating the molecular weight of the compound. A molecular ion is formed when a molecule experiences either the removal or addition of one/multiple electrons.

Determination of the molecular ions

The given molecular formula is ${\text{C}}_{\text{6}}{\text{H}}_{\text{11}}\text{Br}$. Bromine has two isotopes,${}^{\text{79}}{\text{Br\hspace{0.17em}and\hspace{0.17em}}}^{\text{81}}\text{Br}$.

The molecular weight is calculated below:

$\begin{array}{c}{\text{C}}_{\text{6}}{{\text{H}}_{\text{11}}}^{\text{79}}\text{Br\hspace{0.17em}\hspace{0.17em}=\hspace{0.17em}6×12+11×1+79×1}\\ \text{=72+11+79}\\ \text{=162}\end{array}$

$\begin{array}{c}{\text{C}}_{\text{6}}{{\text{H}}_{\text{11}}}^{\text{81}}\text{Br\hspace{0.17em}\hspace{0.17em}=\hspace{0.17em}6×12+11×1+81×1}\\ \text{=72+11+81}\\ \text{=164}\end{array}$

Hence, the molecular ions are 162 and 164.