How did Rutherford come to the conclusion that most of the space in atoms is empty?

Ernest Rutherford was a physicist who conducted the famous gold foil experiment in 1911. This experiment ultimately led him to the conclusion that most of the space in atoms is empty. Let me explain how he reached this conclusion.

1. The setup: Rutherford used a beam of alpha particles (positively charged particles) emitted from a radioactive source and directed them at a thin sheet of gold foil.

2. The expectation: Based on the prevailing model at the time, called the "plum pudding model," Rutherford expected the alpha particles to pass right through the gold foil with only slight deflections. This model proposed that the positive charge was uniformly distributed throughout the atom, with electrons embedded within it.

3. The observation: However, to Rutherford's surprise, some of the alpha particles were scattered at large angles, and a small fraction even bounced straight back. According to the plum pudding model, such deflections were highly improbable.

4. The interpretation: Rutherford analyzed these unexpected results and proposed a new atomic model. He reasoned that since some particles bounced back, they must have encountered a concentrated positive charge. This could only occur if the positive charge resided in a tiny, dense region at the center of the atom, which he called the "nucleus."

5. The conclusion: Rutherford concluded that since most of the alpha particles passed through the gold foil without significant interaction, they must have traversed mostly empty space within the atom. This led him to believe that atoms are mostly empty space, with the electrons occupying regions far away from the nucleus.

In summary, Rutherford's gold foil experiment demonstrated that the majority of an atom's space is empty, with the positive charge concentrated in a small, dense nucleus. This groundbreaking discovery paved the way for our modern understanding of atomic structure.