For the following neutral atoms, give the number of protons, neutrons, and electrons:

Question

195/80 Hg

129/53 I

75/35 Br

137/55 Cs

196/78 Pt

Answer 1

Atomic number = # protons = # electrons (for a neutral atom)

Atomic mass = protons + neutrons

195/80 Hg: 80 protons, 80 electrons, 115 neutrons

129/53 I: 53 protons, 53 electrons, 76 neutrons

75/35 Br: 35 protons, 35 electrons, 40 neutrons

137/55 Cs: 55 protons, 55 electrons, 82 neutrons

196/78 Pt: 78 protons, 78 electrons, 118 neutrons