question archive The mass number is the number of protons added to the number of neutrons
The mass number is the number of protons added to the number of neutrons
Subject:ChemistryPrice: Bought3
The mass number is the number of protons added to the number of neutrons.
Hydrogen only contains 1 proton and no neutrons, so that gives a of 1.
However, there are some isotopes of Hydrogen, in other words, some atoms that have more than zero neutrons. For example, Deuterium has 1 neutrons hence an atomic mass of 2 and Tritium has 2 neutrons hence an atomic mass of 3.
The number you see for atomic mass in a periodic table is an average of the abundance of the isotopes, which is why it's a decimal like ##1.00794## and not a whole number.
