Which of the following was a result of the Rutherford gold-foil experiment?

• A. Most alpha particles passed straight through the foil, but a few were deflected at large angles.
• B. Alpha particles caused the gold foil to emit X-rays.
• C. Alpha particles were completely reflected back toward the source.
• D. All alpha particles were absorbed by the gold foil.

Answer: (A)

Verified step by step guidance

1. Recall the purpose of the Rutherford gold-foil experiment: to investigate the structure of the atom by observing how alpha particles interact with a thin sheet of gold foil.
2. Understand the expected outcomes based on the atomic models at the time: the plum pudding model predicted that alpha particles would pass through with minimal deflection because positive charge was thought to be spread out evenly.
3. Analyze the actual observations from the experiment: most alpha particles passed straight through the foil, indicating that atoms are mostly empty space.
4. Note the surprising result that a small fraction of alpha particles were deflected at large angles, suggesting the presence of a small, dense, positively charged nucleus within the atom.
5. Conclude that the key result was that most alpha particles passed through the foil, but a few were deflected sharply, leading to the nuclear model of the atom.