Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons.What is its atomic number and atomic weight?
A)The atomic number is 79,and the atomic weight is 197.
B)The atomic number is 79,and the atomic weight is 118.
C)The atomic number is 118,and the atomic weight is 197.
D)The atomic number is 118,and the atomic weight is 79.

Question

Quizplus · Accepted Answer

The atomic number is determined by the number of protons in the nucleus, so the gold atom has an atomic number of 79. The atomic weight is the sum of the number of protons and neutrons in the nucleus, so the gold atom has an atomic weight of 197 (79 protons + 118 neutrons). Choice A is the only option that correctly identifies both the atomic number and atomic weight.

Consider an Atom of Gold in Which the Nucleus Contains