The following figure shows the
nuclei of two atoms. Are the atoms of the same isotope
of an element or of different isotopes of that element?
Recall that one element an atom is
an atom of depends on how many protons are contained in the atom’s nucleus. Recall also that different isotopes
of the same element contain different numbers of neutrons.
For the nuclei shown, a proton is
represented by a pink circle containing a plus symbol, and a neutron is represented
by a green circle. We observe that each nucleus
contains a single proton. As both of the nuclei shown contain
the same number of protons, both of the nuclei shown must be of the same element, in
this case the element hydrogen.
We see though that the nuclei
contain different numbers of neutrons to each other. This shows that these nuclei are of
different isotopes. So the correct answer is that the
atoms shown are atoms of different isotopes of the same element.