mass number and isotopes

What would we call this atom?

hydrogen-2

mass number

is the number of protons and neutrons

what property of an atom determines which element it is?

proton number

Chemists measure mass at the atomic level using a unit called the…

This unit is exactly equal to…

atomic mass unit

1/12th of carbon-12 atom

what is the mass of an isotope, measured in?

AMU

what is The mass of an isotope called?

relative isotopic mass

The relative abundance of an isotope

is the number of atoms of that isotope that exists on Earth, as a percentage of all the atoms of that element

Relative atomic mass

is the average mass of one atom of an element relative to one twelfth of the mass of a carbon-12 atom

The relative abundances of all the naturally-occurring isotopes of an element must sum to...

100 percent