Mass number and relative atomic mass?Watch
I know mass numbers and relative atomic numbers are different: the mass number is the number of protons and neutrons in an atom and the RAM is the average weighted mass of the isotopes of that element when compared with carbon-12. What I don't understand is why on the Periodic Table they're the same number? Could you therefore say when referencing to the Perioidc table that the mass number/ram are the same number? Is this always the case? (I'm doing GCSE Chemistry)
Also remember that mass number (of one isotope) can NEVER be anything but a whole number (since it is the proton and neutron count).
Bromine is another fun one, its two stable isotopes have masses of 79 and 81. What is the RAM? What do you notice? How could that have happened?