Exploring Radiation: Structure
| The discovery of radioactive elements by Marie and Pierre Curie had
shown something mysterious was going inside these atoms. What was going
on they did not know. In some way, these radioactive elements must have
a different structure to cause them to give off radiation. If atoms were
tiny little balls that John Dalton had suggested earlier, how could its
inner structure be revealed? These first answers would be given by a scientist
named Ernest Rutherford, whose experiments would virtually create the Nuclear
physics portion of Nuclear Science. |
Ernest Rutherford |
Rutherford began studying uranium radiation. From his experiments
he found that there were two types of radiation given off when elements
broke down., alpha radiation and beta radiation. Alpha radiation
was readily absorbed while beta radiation and a penetration character.
Studying the radiation of the element thorium, Rutherford found that as
it broke down, it not only gave off alpha and beta particles but it also
produced a mysterious gas later named radon.
Further Rutherford found that radioactive substances decayed into
other elements. Atoms, far from being unchanging, could turn into another
kind. Each radioactive substance had a half-life- a specific time it takes
for half of the substance to decay and turn into another substance.
| In 1911, Rutherford conducted an experiment where he bombarded a piece
of gold foil with alpha radiation. Most of the particles passed through
the foil suggesting that much of the foil was empty space. Some particles
however, bounced back pointing out that there was the presence of solid
matter. Rutherford created a type of gun which allowed alpha particles
to be shot in a beam. By running it in the dark and shooting it against
the foil, they could see tiny flashes when an alpha particle would hit
rebound back. The alpha particles that bounced back must have hit something
hard. Rutherford suggested that the atom consisted of a tiny center or
nucleus. |
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In 1919, Rutherford discovered that when nitrogen gas was bombarded
with alpha particles, some hydrogen suddenly showed up. Rutherford suggested
that the nuclei (plural of nucleus) of all atoms actually consisted
of 'hydrogen-sized' particles, which he later named protons. This
would be Rutherford's greatest work in exploring the structure and make-up
or radiation.
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