Rutherford, James

Describe the contributions of the following scientists to our knowledge of atomic structure J. J. Thomson, R. A. Millikan, Ernest Rutherford, James Chadwick. 

James Chadwick was happy to return to England in 1917. He had been studying in Germany at the outbreak of World War 1 and had been imprisoned there for four years. He was broke but alive. Fortunately, his old mentor Ernest Rutherford took him in. His job was to search for the neutral particle that Rutherford believed must exist in the atomic nucleus, a particle he called a neutron. 

The final piece in this subatomic jigsaw (or, at least, in this simple version) was provided by the discovery of the neutron by James Chadwick (1891 1974) in 1932. Chadwick had been a student of Rutherford s in... 

Why this emphasis Schweber has portrayed Slater as a man who developed a deep feeling of both inferiority and competitiveness toward his European mentors and peers in the fields of atomic physics and quantum electrodynamics. Slater was not alone in this reaction, as Henry James made clear. Slater, like other American physicists and chemists, used his influence in Boston, New York, and Washington circles, as well as his position within his own institution, to build up American science in an area where Americans could take a competitive lead. 107 Donnan had written Lewis in 1921 that "you are making old Europe sit up some. If it wasn t for Planck, Einstein, Rutherford, and Bragg, we should be in a bad way." 108 But it was not enough for Europeans to sit up "some" they must be made to gawk. 

The last of the three fundamental particles is the neutron. Experimenters in the early 1930s bombarded elements with alpha particles. One type of particle produced had the same mass of the proton, but carried no charge. James Chadwick (1891-1974), in collaboration with Rutherford, conducted... 

But that cannot be all, Rutherford realized. A helium nucleus may have twice the charge of a hydrogen nucleus but it has four times the mass. He therefore suggested that nuclei also contain particles that have the same mass as protons but no electrical charge. Rutherford s student James Chadwick discovered this neutral particle in 1932, and called it the neutron. 

The patent was rejected on the grounds that it was too sketchy to be comprehensible. The work foundered, and it was soon discovered that the helium was not produced by fusion at all. It was being absorbed from the atmosphere into the glass walls of the vessels used for the experiments. In 1930, no lesser authorities than James Chadwick and Ernest Rutherford dismissed the claims of hydrogen fusion, saying The presence of an element has been mistaken for its creation. ... 

However, in the last hundred years or so it has been proved by great scientists, such as Niels Bohr, Albert Einstein, Henry Moseley, Joseph Thomson, Ernest Rutherford and James Chadwick, that atoms are in fact made up of even smaller sub atomic particles. The most important of these are electrons, protons and neutrons, although 70 sub atomic particles have now been discovered. 

This was initiated by the first description of the atom structure in 1913 by Ernest Rutherford, a British scientist and Niels Bohr, a Danish scientist. Then came the discovery of the neutron in 1932 by James Chadwick (a British student of Rutherford), the discovery of artificial radioactivity by Irene and Frederic Joliot Curie (Nobel Prize in chemistry in 1935) and finally the discovery of fission in 1938 by Lise Meitner, Otto Hahn and Fritz Strassman (German scientists) which brought Hahn the Nobel Prize for physics in 1944. 

By the early twentieth century, chemists and physicists recognized that the atoms of which chemical elements are composed are themselves made up of electrons and protons, of electrically negative and positive subatomic particles that were the universal constituents of all chemical elements. Sir Joseph Thomson had discovered the electron in 1897. Ernest Rutherford postulated the existence of a positive nucleus in atoms in 1911, and he used this in developing his planetary model of the atom, with a positive center and orbiting electrons. He discovered the proton in 1919, in experiments on the disintegration of atomic nuclei. Much later, in 1932, the British physicist James Chadwick (1891— 1974) discovered a third subatomic particle, the electrically neutral neutron. 

Cerdeno-Tarraga AM, Efstratiou A, Dover LG, Holden MT, Pallen M, Bentley SD, Besra GS, Churcher C, James KD, De Zoysa A, Chillingworth T, Cronin A, Dowd L, Feltwell T, Hamlin N, Holroyd S, Jagels K, Moule S, Quail MA, Rabbinowitsch E, Rutherford KM, Thomson NR, Unwin L, Whitehead S, Barrell BG, Parkhill J (2003) Nucleic Acids Res 31 6516... 

So the question naturally arises If atomic particles are so small we can t use our senses to detect them, how do we know they are there By inference. Humankind learned long ago that the input of the senses can be flawed. Optical, olfactory, and tactile illusions abound. So to discover the nature of those parts of the world that cannot be smelled, touched, and seen, people have learned to look at secondary effects and infer their causes. The concept was well captured by the venerated scientist Ernest Rutherford in the advice he gave to James Chadwick when Chadwick was looking for evidence for the neutron. Rutherford advised. 

Rutherford suggested that this nucleus at the center of the atom was composed of densely packed positively charged particles. Soon after, Henry Moseley, before his early death at Gallipoli in World War I, supplied experimental evidence for these particles, the protons. The other particles in the nucleus, the neutrons, proved a bit harder to pin down because they have no charge. But James Chadwick, taking Rutherford s advice, finally confirmed their existence in 1932. Chadwick measured the rebound of certain radiation from nitrogen and helium and found it corresponded to a neutral particle with about the same mass as a proton. ... 

After Ernest Rutherford (1871-1937) discovered the atomic nucleus in 1911, he proposed the name proton for the very lightest of all nuclei the nucleus of the ordinary hydrogen atom. Proto- is Greek for first. In 1932, when James Chadwick (1891-1974) discovered another particle in the nucleus that was very similar to the positive proton except that it was electrically neutral, it was natural for him to call it a neutron. It was then equally natural to call both nuclear particles nucleons, especially when nuclear theory began to treat the proton and the neutron as two different states of the same fundamental particle. 

In 1932, Rutherford s coworker, English physicist James Chadwick (1891-1974), showed that the nucleus also contained another subatomic particle, a neutral particle called the neutron. A neutron has a mass nearly equal to that of a proton, hut it carries no electrical charge. Thus, three subatomic particles are the fundamental building blocks from which all atoms are... 

Rutherford, Ernest (1871-1937) British Physicist Ernest Rutherford was born on August 30, 1871, in Nelson, New Zealand, to James Rutherford, a Scottish wheelwright who emigrated to New Zealand in 1842. His mother, Martha Thompson, an English schoolteacher, followed in 1855. 

Chadwick, Sir James. (1891-1974). A British physicist who was awarded the Nobel Prize in 1935 for his discovery of the neutron (1932), the existence of which had been predicted by Rutherford. 

The proton was observed by Rutherford and James Chadwick in 1919 as a particle that is emitted by bombardment of certain atoms with a-particles. 

Several years later, in 1919, Rutherford discovered the positively charged particle, the proton, that makes up the dense nucleus of an atom. It would be another thirteen years before James Chadwick discovered the neutrally charged neutron, the second component of the nucleus. 

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