How many neutrons are in a hydrogen atom?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

To calculate the number of protons and neutrons in an atom, one needs to know the atomic number and mass number of the atom. The number of protons in an atom is the same as the atomic number. The mass number, on the other hand, is a sum total of the number of protons and neutrons.

Hydrogen has 3 common isotopes (atoms that have the same atomic number but different mass numbers): protium, deuterium, and tritium. All these isotopes have an atomic number of 1, but the mass numbers of these isotopes are 1, 2, and 3, respectively.

This means that all these isotopes have only 1 proton (since the atomic number is 1). However, protium has 0 neutrons (mass number - atomic number=1-1=0), deuterium has 1 neutron (2-1=1), and tritium has 2 neutrons (3-1=2) in it.

See eNotes Ad-Free

Start your 48-hour free trial to get access to more than 30,000 additional guides and more than 350,000 Homework Help questions answered by our experts.

Get 48 Hours Free Access
Approved by eNotes Editorial