Which of the following atomic models is missing from a set that includes Dalton's solid sphere model, Thomson's plum pudding model, and Bohr's planetary model?

• A. Democritus's indivisible atom model
• B. Rutherford's nuclear model
• C. Quantum mechanical model
• D. Lewis dot structure model

Answer: (B)

Verified step by step guidance

1. Review the given atomic models: Dalton's solid sphere model, Thomson's plum pudding model, and Bohr's planetary model. Each represents a historical development in atomic theory.
2. Recall the sequence of atomic models historically: Democritus proposed the idea of indivisible atoms, Dalton introduced solid spheres, Thomson discovered electrons leading to the plum pudding model, Rutherford discovered the nucleus leading to the nuclear model, and Bohr introduced quantized orbits.
3. Identify which model is missing from the set by comparing the known models in the problem with the historical progression. Notice that Rutherford's nuclear model, which introduced the concept of a dense nucleus, is not listed among the given models.
4. Understand that the quantum mechanical model and Lewis dot structure are more modern or represent different aspects of atomic theory, but the key missing classical model in the sequence is Rutherford's nuclear model.
5. Conclude that the missing atomic model from the set is Rutherford's nuclear model, which bridges Thomson's and Bohr's models by introducing the nucleus.