Question #37c39
1 Answer
Atoms are mostly composed of empty space.
Explanation:
Rutherford's gold foil experiment used an alpha particle source to probe the structure of the atom. In the experiment, conducted by Ernest Marsden (because he was young and had good eyes), an alpha source was placed in a lead cavity so that a stream of alpha particles were emitted.
These alpha particles, each with a +2 charge, were directed against a gold foil, probably about 2,000 atoms thick. For a detector, they used a zinc sulfide screen which would show tiny flashes of light every time an alpha particle hit the screen. Marsden used a microscope to watch the screen and he recorded the flashes, noting the angle the screen was at compared to the line of alpha particles.
The vast majority of the alpha particles went straight through the gold film as if it were not there. However, a very small fraction of the alpha particles were deflected by wildly varying amounts.
From these observations, Rutherford reasoned that the atom was composed of a small positively charged nucleus with a large volume of negative charge surrounding it.
