Simplify the following text for a Grade 10 native English-speaking person.
Original: The nucleus of tritium ( sometimes called a triton ) contains one proton and two neutrons , whereas the nucleus of protium ( by far the most abundant hydrogen isotope ) contains one proton and no neutrons .
Simplified: Tritium has one proton and two neutrons , making it heavier than ordinary hydrogen or its isotope deuterium . Hydrogen does not have any neutrons , only a proton .