Hydrogen has the lightest atom of all elements. The atom of the most common isotope of hydrogen known as protium does not have any neutrons; it only has one proton and one electron in the neutral state. This gives it an atomic weight of 1.
There are other isotopes of hydrogen, one of them with one neutron and the other with 2 neutrons. The isotope with a single neutron is known as deuterium and has an atomic weight of 2. The isotope with 2 neutrons is called tritium and the two neutrons give this isotope an atomic weight of 3.
Hydrogen has three isotopes-
- protium has 1 neutron
- deuterium has 2 neutrons
- tritium has 3 neutrons
since isotopes have same atomic number,all the three have 1 proton and 1 electron.
Electrons = 1 , protons = 1, neutrons = 0