Rutherford's Gold Foil Experiment

Rutherford's Gold Foil Experiment

Read the information and answer the questions about Rutherford's Gold Foil Experiment.

Before Rutherford's experiment, scientists thought atoms were like plum puddings, with positive charge spread out and tiny negative electrons mixed in. Ernest Rutherford and his team wanted to test this idea.

They fired tiny, positively charged particles (called alpha particles) at a very thin sheet of gold foil. Around the gold foil, they placed a screen that would light up when an alpha particle hit it, so they could see where the particles went.

1. What were the tiny, positively charged particles used in the experiment called?

2. What material was used to make the thin sheet in the experiment?

Most of the alpha particles passed straight through the gold foil, as if nothing was there. This showed that atoms are mostly empty space.

A few particles were deflected (bent) at large angles. This meant they hit something small and positively charged inside the atom, because positive charges repel each other.

A very small number of particles bounced straight back! This was like firing a cannonball at a tissue paper and having it bounce back. It showed that there was a very dense, tiny, positively charged center in the atom. Rutherford called this the **nucleus**.

3. Most alpha particles went straight through the gold foil, showing that atoms are mostly   space.

4. The very dense, tiny, positively charged center of an atom is called the  .

5. Before Rutherford's experiment, scientists believed the atom was mostly empty space.

6. How did the gold foil experiment change our understanding of the atom?