If an atom has 2 protons, 2 electrons, and 1 neutron, its atomic mass will be ______?
If an atom has 2 protons, 2 electrons, and 1 neutron, its atomic mass will be ______?
Explanation
Atomic mass = number of protons + number of neutrons → 2 + 1 = 3.
Electrons do not contribute significantly to atomic mass.