Ernest Rutherford (704 words)

Ernest Rutherford
Ernest Rutherford was born in New Zealand in 1871 as one of 12 children. It was
Rutherford who first “split” an atom and who discovered the atomic
“nucleus”, a name that he invented. For this he is regarded as the
greatest experimental physicist of his time. Rutherford was one of the first and
most important researchers in nuclear physics. Soon after the discovery of
radioactivity in 1986 by the French physicist Antoine Henri Becquerel,
Rutherford discovered the three different types of radiation. By covering his
Uranium with thin foils of aluminum, gradually increasing the number of foils.

For the first three layers of foil the radiation escaping from the uranium
decreased progressively, suggesting an ordinary law of absorption. More
thickness of aluminum, however, had little further effect in reducing the
radiation at first, but eventually the intensity of the radiation began to
diminish again as even more foils were added. These experiments showed that
there were at least two distinct types of radiation- one that is very readily
absorbed, which he called the alpha – radiation, and the other more penetrative
character which he called the beta – radiation. He also had believed that he had
found a third more penetrating radiation. The Frenchman, Paul Villard,
officially gave this third radiation. He named it, after Rutherford’s first two
radiation discoveries, the gamma- radiation. It was these discoveries in
radiation that opened the door to the rest of Rutherford’ discoveries. Using
this alpha radiation, Rutherford started to experiment putting it through other
materials to get the effects. It was in one of these experiments with gold that
he was able to figure out what an atom looks like. He found that a countable
number of alpha particles actually bounced back from a thin sheet of gold foil.

Of course the majority of the particles went straight through the gold and were
only slightly scattered. Rutherford said that this was the most surprising
result he had known. He said that this discovery of the alpha particles actually
bouncing off the gold was as surprising to him as firing a fifteen inch shell at
a piece of tissue paper and having it bounce back and hit you. From this
statement we can see how immersed Rutherford actually was in his studies. By
this experiment it seemed clear to Rutherford that the alpha particle
occasionally encountered such an intense field in the atom that it was turned
back in its path as the result of a collision. When considering the mass and
energy of an alpha particle this was an astonishing observation. Rutherford said
that in order to produce such a large deflection of the alpha particle, the atom
must contain a massive charged center of very minute dimensions. From this arose
the concept of the well known “nucleus” (a name which Rutherford
coined), where the atom consists of a minute positively charged nucleus
containing most of the mass of an atom, surrounded at relatively great distances
by electrons. He also discovered that the alpha particle was repelled according
to the ordinary laws of electricity so that it should travel in a hyperbola.

From this he discovered the law of scattering, that is to say the number of
particles that should be found at any angle of deflection. Rutherford was
confident that we would get more information from scattering about the nature of
the atom than any other method. Rutherford became very excited about an idea
that Darwin had given him about the interesting results that might occur when an
alpha particle met a nucleus lighter than itself, such as the nucleus of a
hydrogen atom. Rutherford went to work right away. In 1919 Rutherford performed
a pioneer experiment in nuclear physics when he bombarded nitrogen gas with
alpha particles and obtained atoms of an oxygen isotope and protons. This
process of changing nitrogen into oxygen was the first artificially induced
nuclear reaction. It also made great headway in the following decades of
intensive research on the other nuclear transformation sand on the nature and
properties of radiation. Today, with the threat of nuclear weapons and the
promise of nuclear power it must appear that the splitting of the atom was
Rutherford’s most significant achievement. Rutherford was elected a fellow of
the Royal Society in 1903 and served as president of that institution from 1925
to 1930. He was awarded the 1908 Nobel Prize in chemistry, was knighted in 1914,
and was created a baron in 1931. He died in London on October 19, 1937, and was
buried in Westminster Abbey.