If you want to change the mass of an atom what do you do

The mass of an individual atom will not change unless the atom undergoes a nuclear change. The average mass of an element remains essentially staple as an average of the common isotopes. However the mass number of a sample of an element can and will change over time as the radioactive isotopes undergo nuclear changes.

Explanation:

Is it right

The atomic mass is the sum of the protons and neutrons. As the atomic number increases it causes an increase in the atomic mass.

Explanation:

The number of neutrons in a nucleus affects the mass of the atom but not its chemical properties. Thus, a nucleus with six protons and six neutrons will have the same chemical properties as a nucleus with six protons and eight neutrons, although the two masses will be different.

a electronegativity decreases beacuse the size of nucleus is bigger.