How do you find the average atomic mass

The difference between the atomic number of an element and the element’s atomic mass is the number of ions.

In the 1800s, one of the statements in john dalton's atomic theory was that atoms are indivisible. later experimental evidence led to the discovery of subatomic particles such as neutrons, electrons, and protons. what happened to the indivisible atom part of dalton's atomic theory, and why?

What is the mass of oxygen gas is consumed in a reaction that produces 4.60mol so2