Questions: Atomic mass has a decimal because it is the average of all the isotopes for a particular element. The atomic number of an element is the number of in its nucleus. A number of electrons; protons B mass; protons C mass; neutrons D protons; neutrons

Solution Steps

The atomic mass of an element is a weighted average of the masses of all its isotopes. This is why it often has a decimal value.

The atomic number of an element is defined as the number of protons in its nucleus. This is a whole number and unique to each element.

• The first blank should be filled with "mass" because atomic mass is the average of all isotopes.
• The second blank should be filled with "protons" because the atomic number is the number of protons in the nucleus.

Final Answer