Question

The atomic number of an atom is determined by its1) number of electrons.2) number of protons.3) number of neutrons.4) sum of protons and neutrons.

Answer 1

The atomic number of an atom can be said to be defined by the number of protons in an element.

An atom can be said to be the part of an element. It defines a particle of matter that uniquely defines an element.

A proton is a stable subatomic particle which contains a positive charge that forms part of the nucleus of an atom. A proton determines the atomic number of an atom.

Therefore, the number of protons in an element determines the atomic number.

ANSWER:

2) Number of protons.