Question

q 11. the number of protons in an atom. number identifies the number atomic number atomic radius atomic mass electron shells

Explanation:

The atomic number of an element is defined as the number of protons in the nucleus of an atom of that element. It is a unique identifier for each element. Atomic radius is a measure of the size of an atom, atomic mass is the mass of an atom, and electron - shells are the regions around the nucleus where electrons are likely to be found.

Answer:

Atomic Number