sotopes are different forms of the same element. They have the same proton (and electron) numbers, but different neutron (and mass) numbers. Since the number of electrons of isotopes are the same, the chemical properties are also the same, as chemical reactions require the transfer/sharing of electrons. However, the physical properties of isotopes differ, since the mass numbers are different, that means the melting/boiling points and density of isotopes are also different. Let’s investigate the isotopes of carbon: 12C and 13C Since we know isotopes have the same proton and electron numbers, we can find the number of protons of both carbon isotopes using the Periodic Table. We can then find the neutron number by subtracting the proton number from the mass number: Protons + Neutrons = Mass Number Neutrons = Mass Number - Protons Thus, from the table we can clearly see that the proton and electron numbers of the two isotopes are the same, but they differ in the neutron, hence, mass numbers. Helpful Content: https://www.sciencedirect.com/topics/earth-and-planetary-sciences/isotope https://socratic.org/questions/how-do-isotopes-differ-from-each-other https://study.com/academy/lesson/what-are-isotopes-definition-types-examples.html https://theconversation.com/explainer-what-is-an-isotope-10688 https://www.britannica.com/science/isotope https://en.wikipedia.org/wiki/Isotope http://www.uky.edu/~garose/atoms.htm https://courses.lumenlearning.com/introchem/chapter/isotopes/