Question

What is the notation for a copper atom that contains thirty-four neutrons?

Answer 1

Well it is simply `""^63Cu`....

Explanation:

We don't need to add the atomic number `Z`, here, `29`, because the `Cu` symbol SPECIFIES a nucleus that contains 29 massive, positively charged particles..... So how many electrons in the neutral atom?

Answer 2

We could write it as `""^63Cu` or `""_29^63Cu`.

Explanation:

If we look on the periodic table, it shows that copper `(Cu)` has an atomic number of `29`, and so it has `29` protons.

If it has `34` neutrons, then its total mass is `34+29=63` units.

We would write the notation as:

`""_29^63Cu`

Even shorter, we know that only an atomic number defines the element's identity, and so we can remove the bottom number, and write the isotope notation as simply as:

`""^63Cu`