Which of the following best describes Rutherford's contribution to atomic theory based on his gold foil experiment?

• A. He determined that atoms consist mostly of neutrons.
• B. He proposed that atoms have a small, dense, positively charged nucleus.
• C. He suggested that atoms are indivisible and solid spheres.
• D. He discovered that electrons orbit the nucleus in fixed energy levels.

Answer: (B)

Verified step by step guidance

1. Recall the context of Rutherford's gold foil experiment, which involved firing alpha particles at a thin sheet of gold foil to observe their scattering patterns.
2. Understand that most alpha particles passed straight through the foil, but some were deflected at large angles, indicating the presence of a small, dense, positively charged center within the atom.
3. Recognize that this observation led Rutherford to propose a new atomic model where the atom consists mostly of empty space with a tiny, dense nucleus at the center containing positive charge.
4. Note that this nucleus contains protons (and later discovered neutrons), but Rutherford's key contribution was the concept of the nucleus itself, not the detailed composition of neutrons or electron energy levels.
5. Compare this with other atomic models: the indivisible solid sphere model was proposed by Dalton, and the fixed energy levels for electrons were introduced later by Bohr.