What is an isotope?
Isotopes are basically atoms which have the same no. of protons but different no. of neutrons at its nucleus.
Isotopes are atoms that have the same proton no. but different nucleon no.
The chemical properties of an element is determined by its electronic configuration, which is then determined by the no. of protons it has. Since isotopes have the same no of protons at its nucleus, they have the same chemical properties.
However the fact that they have different no. of neutrons means that the isotopes will have different physical properties (e.g. density, mass). For example, if there are two isotopes with different nucleon no., the one which has a higher nucleon no. will be more dense than the other one, since it has more no. of neutrons at its nucleus.