Question

What is the atomic number of an element equal to?

Answer 1

The atomic number, `Z`, is equal to the number of protons, positively charged nuclear particles, that reside in the element's nucleus.

Explanation:

`Z=1`, the element is hydrogen, `Z=2`, the element is helium, .....`Z=6`, the element is carbon..........`Z=17`, the element is chlorine.

Now sometimes in chemistry, when we say proton, we mean the `H^+" or "H_3O^+` ion. Here, in the context of atomic physics, we mean a massive, positively charged nuclear particle, whose number defines the identity of the nucleus.

Two questions:

`"Do you have to remember these numbers?"`

`"In the neutral ATOM how many electrons are there compared"` `"to Z?"`