You would also need to know the abundance of each of the isotopes, i.e., how much percent of each you will typically encounter.
the Atomic Mass
The weighted average for all isotopes that occur in nature for an element is its atomic weight listed on the Periodic Table of the elements.
The abundance percentage of each isotope
The atomic weight that is listed on the periodic table for each element is the weighted average of the atomic masses of an element's naturally occurring isotopes. So you are describing atomic weight as it is used on the periodic table.
the mass of the isotopes
the atomic number of each isotope-apex;)
Atomic mass is the average mass of all isotopes of a given element.
the Atomic Mass
The atomic mass of an element is the average of its isotopes, weighted by abundance in nature.
The atomic mass of an element is the average of its isotopes, weighted by abundance in nature.
The weighted average for all isotopes that occur in nature for an element is its atomic weight listed on the Periodic Table of the elements.
The average of all the naturally occurring isotopes of a particular element are an element's atomic Mass.
The abundance percentage of each isotope
the atomic mass
This is the atomic weight.
The atomic weight that is listed on the periodic table for each element is the weighted average of the atomic masses of an element's naturally occurring isotopes. So you are describing atomic weight as it is used on the periodic table.
The average atomic mass of an element is the average of the atomic masses of its isotopes (that is a weighted average). You have to take into account the abundance of each isotope when they do your averaging.