How are isotopes of the same element alike? How are they different?

They have the same number of protons and different number of neutrons

Explanation:

Isotopes tend to vary in their mass numbers in which this is due to the changing number of neutrons but at the same time their protons remain the same

See below.

Explanation:

They have the same number of protons in the nucleus so their chemical properties are the same.

Their atomic masses are different due to the different number of neutrons in the nucleus. Some of the isotopes of an element may be radioactive.