The atom's mass is determined by the number of __ neutrons and electrons protons and neutrons protons and electrons

## Step 1<br />The mass of an atom is primarily determined by the number of protons and neutrons it contains. These particles are located in the nucleus of the atom and are much heavier than electrons.<br /><br />## Step 2<br />Electrons, although they are a part of an atom, contribute very little to the overall mass of an atom. This is because they are located in the electron cloud, which is far away from the nucleus, and their mass is negligible compared to that of protons and neutrons.<br /><br />## Step 3<br />Therefore, the number of protons and neutrons in an atom determines its mass.