Answer:
Explanation:
Every element is constituted by atoms with the same atomic number, which is the number of protons in their nuclei. So, all the atoms of a same element have the same number of protons.
For instance, the element sodium has atomic number 11, and all its atoms have 11 protons.
The atomic number identifies uniquely every element.
In the atomic nuclei there are protons and neutrons. Neutrons can vary from one atom of a particular element to another atom of the same element. That is what the term isotope accounts for. Isotopes are atoms with the same atomic number and different number of neutrons.
Most elements have different isotopes. The atomic mass of fifferent isotopes of a particular element will differ among them, because the neutrons account for the mass.
