Is the mass of a hydrogen atom is different from the mass of a oxygen atom?
Mass of an atom is due to protons and neutrons present in an atom and number of proton is something that distinguish between atoms, therefore mass of hydrogen is different to the mass number of oxygen, hydrogen’s mass is 1 as it has only 1 proton and no neutrons, and oxygen mass’s is 16 as it has 8 protons and 8 neutrons.