In the Rutherford gold foil experiment, what did Rutherford conclude about the alpha particles that were deflected at large angles?

• A. They were attracted to negatively charged particles in the atom.
• B. They were absorbed by electrons surrounding the nucleus.
• C. They passed through empty space without any interaction.
• D. They were repelled by a small, dense, positively charged nucleus in the atom.

Answer: (D)

Verified step by step guidance

1. Recall the setup of the Rutherford gold foil experiment, where alpha particles (which are positively charged) were directed at a thin sheet of gold foil.
2. Understand that most alpha particles passed through the foil with little or no deflection, indicating that atoms are mostly empty space.
3. Focus on the observation that a small fraction of alpha particles were deflected at very large angles, some even bouncing back toward the source.
4. Analyze what could cause such strong deflections: since alpha particles are positively charged, they would be repelled by a region of concentrated positive charge within the atom.
5. Conclude that Rutherford deduced the existence of a small, dense, positively charged nucleus at the center of the atom responsible for repelling the alpha particles at large angles.