# There are seven naturally occurring diatomic molecules. What are they?

Apr 10, 2018

Well, five of them are gases, one a liquid, and one a solid at ${25}^{\circ} \text{C}$ and $\text{1 atm}$. But if you mean which ones actually are found as such,

The five gases are ${\text{H}}_{2}$, ${\text{N}}_{2}$, ${\text{O}}_{2}$, ${\text{F}}_{2}$, and ${\text{Cl}}_{2}$, while the liquid is ${\text{Br}}_{2}$ and the solid is ${\text{I}}_{2}$. To prove it, here are their respective boiling points at $\text{1 atm}$:

${T}_{b} \left({H}_{2}\right) = - {252.9}^{\circ} \text{C}$
${T}_{b} \left({N}_{2}\right) = - {195.8}^{\circ} \text{C}$
${T}_{b} \left({O}_{2}\right) = - {183.0}^{\circ} \text{C}$
${T}_{b} \left({F}_{2}\right) = - {188.1}^{\circ} \text{C}$
${T}_{b} \left(C {l}_{2}\right) = - {34.04}^{\circ} \text{C}$
${T}_{b} \left(B {r}_{2}\right) = {58.00}^{\circ} \text{C}$
${T}_{b} \left({I}_{2}\right) = {184.2}^{\circ} \text{C}$

You should be able to say why these show that the molecule is a gas, liquid, or solid at room temperature, i.e. for which of these is ${T}_{b} > {25}^{\circ} \text{C}$ (if so, we have a liquid), etc.