# What are the numbers of the subatomic particles in neon?

Well, for neon gas $Z \text{ the atomic number} = 10$
Given $Z$, we thus know that there are 10 positively charged protons in the neon nucleus. In order to attain electrical neutrality, there must also be 10 extranuclear electrons. We are not done yet because the nucleus also contains neutrons, massive nuclear particles of zero charge. The common isotope of $N e$ is ""^20Ne, and thus there are 10 neutrons.
You should not have to remember the atomic number, because before a test you should be issued a Periodic Table. You will nevertheless have to be able to interpret the data on the table; certainly you have to know what $Z$ signifies.