Which of the following claims did J.J. Thomson make about the structure of the atom?

• A. Atoms consist of a positively charged sphere with negatively charged electrons embedded within it.
• B. Atoms are made up of protons, neutrons, and electrons.
• C. Atoms have a dense, positively charged nucleus surrounded by electrons.
• D. Atoms are indivisible and cannot be broken down into smaller particles.

Answer: (A)

Verified step by step guidance

1. Understand the historical context of atomic models before J.J. Thomson's work, where atoms were thought to be indivisible particles.
2. Recall that J.J. Thomson discovered the electron, a negatively charged particle smaller than the atom, which led him to propose a new atomic model.
3. Recognize that Thomson's model is often called the 'plum pudding model,' where the atom is described as a positively charged sphere with negatively charged electrons embedded within it.
4. Compare Thomson's claim to other atomic models: the nuclear model (dense nucleus with electrons around it) came later with Rutherford, and the proton-neutron-electron model was developed after Thomson's time.
5. Conclude that Thomson's key claim was that atoms consist of a positively charged sphere with negatively charged electrons embedded within it, which was a major step forward from the idea of indivisible atoms.