Determine the number of protons, electrons, and neutrons for the isotope gold-118. The symbol for gold is Au.
A) 118 protons, 118 electrons, 79 neutrons
B) 79 protons, 79 electrons, 118 neutrons
C) 79 protons, 79 electrons, 39 neutrons
D) 118 protons, 118 electrons, 39 neutrons
E) 79 protons, 39 electrons, 118 neutrons

Question

Quizplus · Accepted Answer

Gold (Au) has an atomic number of 79, which means it has 79 protons and, in a neutral atom, 79 electrons. The isotope gold-118 refers to the mass number, which is the sum of protons and neutrons. Therefore, to find the number of neutrons: 118 (mass number) - 79 (protons) = 39 neutrons.

Determine the Number of Protons, Electrons, and Neutrons for the Isotope