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.