In Rutherford's gold foil experiment, what caused the deflection of the alpha particles?

• A. Collisions with other alpha particles
• B. The gold foil's surface impurities
• C. The positively charged nucleus of the gold atoms
• D. The electrons surrounding the gold atoms

Answer: (C)

Verified step by step guidance

1. Recall the setup of Rutherford's gold foil experiment: alpha particles (which are positively charged) were directed at a very 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. Recognize that some alpha particles were deflected at large angles, which suggested the presence of a small, dense, positively charged center within the atom.
4. Identify that this center is the nucleus of the gold atoms, which repels the positively charged alpha particles due to electrostatic forces.
5. Conclude that the deflection of alpha particles was caused by their interaction with the positively charged nucleus of the gold atoms, not by collisions with other alpha particles, surface impurities, or electrons.