You're absolutely right! You're describing the Rutherford scattering experiment, a landmark experiment in nuclear physics conducted by Ernest Rutherford and his colleagues in the early 20th century.

Here's a breakdown of what happened:

* The Setup: Alpha particles (positively charged helium nuclei) were fired at a thin gold foil.

* The Expectation: Based on the prevailing "plum pudding model" of the atom (where positive charge was thought to be distributed throughout the atom), the alpha particles were expected to pass through the foil with only slight deflections.

* The Surprise: To everyone's astonishment, a small but significant fraction of the alpha particles were deflected at very large angles, some even bouncing back directly towards the source!

* The Interpretation: Rutherford realized that this scattering pattern could only be explained if the positive charge of the atom was concentrated in a tiny, dense core called the nucleus. The alpha particles, being positively charged, were repelled by this positively charged nucleus, causing the large deflections.

Key takeaways from the Rutherford scattering experiment:

* The atom is mostly empty space.

* The positively charged nucleus is a tiny, dense region at the center of the atom.

* The electrons orbit the nucleus at a relatively large distance.

This experiment revolutionized our understanding of atomic structure and paved the way for further developments in nuclear physics.