How do you calculate the number of protons, neutrons and electrons in the atom of a certain element?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

For the number of protons, we look at the atomic number of the element given. Take note that atoms must have equal numbers of protons and electrons. For the number of neutron, we must know the mass number. To find the mass number, all we need to do is round the atomic weight...

Unlock
This Answer Now

Start your 48-hour free trial to unlock this answer and thousands more. Enjoy eNotes ad-free and cancel anytime.

Start your 48-Hour Free Trial

For the number of protons, we look at the atomic number of the element given. Take note that atoms must have equal numbers of protons and electrons. For the number of neutron, we must know the mass number. To find the mass number, all we need to do is round the atomic weight to the nearest whole number (if the atomic weight is given).

After knowing what the mass number is, we use the formula below to calculate the number of neutrons.

Mass Number = (Number of Protons) + (Number of Neutrons).

Approved by eNotes Editorial Team