How many protons, nuetrons, and electrons are in
18 2-
O
8
Look at your formula and/or the periodic table. Everything you need is there.
O = oxygen.
8 = atomic number = number of protons.
18 = mass number = number of protons + number of neutrons.
-2 charge = number of electrons. The number of electrons is the same as the atomic number (that is, the number of protons and number of neutrons is the same in a NEUTRAL atom. If it is -2 that means there are two more electrons; therefore, O^-2 would have 10 electrons).