True.
Scientists want an easy to understand and easy to follow system for finding how much atoms weight.
So they needed a starting point, something to base it off of.
They decided on Carbon 12, that is, a Carbon with 12 unit things (6 neutrons + 6 protons), and is easy to come across and fairly pure.
Protons and Neutrons weigh the same amount.
So they weigh a Carbon 12, and then said that whatever mass it had was 12 AMU (atomic mass unit). That is why when you look at atomic masses on period tables you will see all elements that are not carbon have a decimal value due to isotopes, but Carbon is exactly 12.0000 in all tables I have seen.
Scientists want an easy to understand and easy to follow system for finding how much atoms weight.
So they needed a starting point, something to base it off of.
They decided on Carbon 12, that is, a Carbon with 12 unit things (6 neutrons + 6 protons), and is easy to come across and fairly pure.
Protons and Neutrons weigh the same amount.
So they weigh a Carbon 12, and then said that whatever mass it had was 12 AMU (atomic mass unit). That is why when you look at atomic masses on period tables you will see all elements that are not carbon have a decimal value due to isotopes, but Carbon is exactly 12.0000 in all tables I have seen.