What is an isotope?

Isotopes are elements that have the same number of protons as the standard example in the periodic table, but have a different amount of neutrons.An example of this is C-12, C-13 and C-14. C-12 is the standard example of carbon whereas C-13 and C-14 have added neutrons. Isotopes still chemically react in the same way, because they all have the same about of electrons. However, the higher the number on the isotope, the greater the mass of the atom.