Question

1. what determines what element an atom is - its very identity?

number of protons
number of neutrons
number of electrons
rewatch

Explanation:

The atomic number, which is the number of protons in an atom's nucleus, defines the element. Changing the number of protons changes the element. Neutrons affect isotopes and electrons are involved in chemical bonding but do not determine the element's identity.

Answer:

Number of protons