Final answer:
Isotopes are different forms of an element with the same number of protons but a different number of neutrons. The three isotopes of Hydrogen are Protium, Deuterium, and Tritium.
Step-by-step explanation:
Isotopes are different forms of an element that have the same number of protons but a different number of neutrons. For example, Carbon-12 has 6 protons, 6 neutrons, and 6 electrons, while Carbon-14 has 6 protons, 8 neutrons, and 6 electrons.
The three isotopes of Hydrogen are Protium, with no neutrons; Deuterium, with one neutron; and Tritium, with two neutrons.