The neutron was discovered in 1932 by James Chadwick, when he bombarded beryllium-9 with an alpha particle. The products were a neutron and another nuclide. What is the other nuclide?

Question

Quizplus · Accepted Answer

The mass number of beryllium-9 is 9, and the mass number of an alpha particle (helium-4) is 4, so the total mass number on the left side of the equation is 9 + 4 = 13. Since the neutron has a mass number of 1, the other nuclide must have a mass number of 12 (13 - 1 = 12). The only option with a mass number of 12 is carbon-12, so the answer is D.

The Neutron Was Discovered in 1932 by James Chadwick, When