# Is the molecular mass of nitrogen gas 28*"amu"?

Aug 5, 2017

$\text{Nitrogen gas}$ does indeed have a molecular mass of $28 \cdot g \cdot m o {l}^{-} 1$. How do I know this........?

#### Explanation:

Well, I know this because I have access to a Periodic Table of elements, which tells us the atomic mass of all the known elements. Such Periodic Tables should be made available to you in all examinations in Chemistry and Physics that you ever sit.

And the Periodic Table lists $\text{(i) atomic number, Z}$, and $\text{(ii) atomic mass}$. The atomic number of nitrogen is 7, i.e. there are 7 protons in the nitrogen nucleus....and (usually) 7 neutrons, 14 massive particles thus reside in most nitrogen nuclei.

But we are not finished there. Nitrogen is a room temperature, $\text{binuclear gas}$, i.e. ${N}_{2}$, and inorganic chemists often refer to this as $\text{dinitrogen}$ to emphasize the molecularity. In fact ALL the elemental gases, i.e. dihydrogen, dioxygen, dinitrogen, difluorine, dichlorine, are BINUCLEAR (save of course the Noble Gases.......which have very limited chemistry).

Have you got a Periodic Table beside you? You will soon remember the molar masses of common elements...........