What did Ernest Rutherford discover as a result of his gold foil experiment?

• A. Electrons are arranged in fixed orbits around the nucleus.
• B. Atoms have a small, dense, positively charged nucleus.
• C. Protons and neutrons are evenly distributed throughout the atom.
• D. Atoms are indivisible and solid spheres.

Answer: (B)

Verified step by step guidance

1. Understand 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. Recall that before Rutherford's experiment, the prevailing atomic model was the 'plum pudding model,' which suggested that positive charge was spread out evenly in the atom.
3. Analyze the key observation: most alpha particles passed straight through the foil, but some were deflected at large angles, indicating the presence of a concentrated positive charge.
4. Conclude that Rutherford discovered atoms contain a small, dense, positively charged nucleus where most of the atom's mass is concentrated, explaining the deflection of alpha particles.
5. Recognize that this discovery disproved the idea that atoms are indivisible solid spheres and led to the nuclear model of the atom.