Question

What do all atoms in a piece of pure copper have in common?

Answer 1

All copper atoms have `"29 protons"` in their nuclei.

Explanation:

By definition, a copper atom has `"29 protons"`, 29 positively charged particles in their nuclei; i.e. `Z=29`. This is what defines the particle as a copper atom, i.e. `Z="atomic number"` determines the element.

The nucleus MAY contain approx. 34-35 neutrons, massive, neutrally charged particles, in their nuclei, and the differing number of neutrons gives rise to the existence of copper isotopes:

`""^63Cu, 69%;""^65Cu, 31%`.