Neutrons were discovered by?

Analysis

The question asks for the scientist credited with the discovery of the neutron, a subatomic particle found in the nucleus of an atom.

Concept

To answer this, we must look at the history of atomic theory and the key scientists involved in discovering the components of the atom:

• John Dalton: Proposed the atomic theory, suggesting atoms are indivisible spheres.
• J.J. Thomson: Discovered the electron using cathode ray tubes (the "Plum Pudding" model).
• Ernest Rutherford: Discovered the nucleus and the proton through his famous gold foil experiment.
• James Chadwick: Conducted experiments in 1932 bombarding beryllium with alpha particles, which led to the discovery of a neutral particle with a mass similar to the proton—the neutron.

Solution

1. Evaluate the options: • John Dalton (D): Known for his early atomic theory, not the discovery of subatomic particles. • J.J. Thomson (C): Discovered the electron. • Ernest Rutherford (B): Discovered the proton and the atomic nucleus. • James Chadwick (A): Successfully identified the neutron, completing our basic understanding of the atom's structure.
2. Conclusion: James Chadwick is the scientist who experimentally confirmed the existence of the neutron in 1932.

Exam Tip

A great way to remember this for your JAMB exam is the mnemonic "PEN":

• Proton: Rutherford
• Electron: Thomson
• Neutron: Chadwick (Think: Proton-Rutherford, Electron-Thomson, Neutron-Chadwick).