Question

1. atomic number also gives the ______ or identity of an atom.

Explanation:

The atomic number of an atom is equal to the number of protons in its nucleus. This number also determines the element (the identity) of the atom because each element has a unique atomic number. So the blank should be filled with "element" (or "proton number" but in the context of identity, "element" is more appropriate as atomic number defines the element's identity).

Answer:

element