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

Jun 10, 2017

All copper atoms have $\text{29 protons}$ in their nuclei.
By definition, a copper atom has $\text{29 protons}$, 29 positively charged particles in their nuclei; i.e. $Z = 29$. This is what defines the particle as a copper atom, i.e. $Z = \text{atomic number}$ determines the element.
""^63Cu, 69%;""^65Cu, 31%.