If the number of electrons in an atom is 8 and the number of protons is also 8, then

(a) Atomic number is equal to the number of protons in one atom. Since this atom contains 8 orotons, so the atomic is 8

(b) This atom contains an equal number of positively charged and negatively charged electrons (8 each), so it has no overall charge. That is, the charge on this atom is 0 (zero).