Final answer:
Isotopes of the same element differ in the number of neutrons, thus altering their mass number, but not their chemical behavior, which is determined by their electron configuration.
Step-by-step explanation:
Isotopes: What Are They?
Isotopes are atoms of the same element with the same atomic number (number of protons) but different mass numbers due to varying numbers of neutrons in the nucleus. For example, all carbon atoms have six protons, but some have seven (carbon-13) or eight (carbon-14) neutrons, making them isotopes of carbon.
Chemical Behavior of Isotopes
The chemical properties of isotopes of the same element are identical because these properties are governed by electrons in the atom's outer shell, which are the same for all isotopes of an element. The differing number of neutrons does not affect the chemical reactivity of an atom, which is why carbon-12 and carbon-13 have the same chemical behavior.
Isotopes and Mass Number
The mass number (A) of an isotope is the sum of protons and neutrons in the nucleus. Isotopes of an element therefore differ only in the number of neutrons they contain. For instance, carbon-12 has a mass number of 12 (6 protons and 6 neutrons), whereas carbon-13 has a mass number of 13 due to an additional neutron.