Rutherford, Ernest atomic theory

Ernest Rutherfords proposed atomic structure added to the problems posed to nineteenth century physics by the ultraviolet catastrophe and the photoelectric effect. Rutherfords atom had a negatively charged electron circling a positively charged nucleus. The physics of the day predicted that the atom would emit radiation, causing the electron to lose energy and spiral down into the nucleus. Theory predicted that Rutherfords atom could not exist. Clearly, science needed new ideas to explain these three anomalies. 

Though the Alchemical Society included academic chemists in its ranks, and productively worked out spiritual implications of modem science for them, none of the scientists in the Alchemical Society directly contributed to the major discoveries and theoretical innovations of modem atomic theory. But Ernest Rutherford and Frederick Soddy s laboratory at McGill was the site of a... 

RUTHERFORD, ERNEST (1871-1937). Rutherford was a British physicist who was bom in the South Island of New Zealand and is famous for his pioneering work in nuclear physics and for his theory of the structure of the atom. 

See section 0006 for the contributions to atomic theory of John Dalton, J. J. Thomson, Max Planck, Ernest Rutherford, Niels Bohr, Louis de Broglie, Werner Heisenberg, and Erwin Schrodinger. 

Medieval alchemists spent years trying to convert other metals into gold without success. Years of failure and the acceptance of Dalton s atomic theory early in the nineteenth century convinced scientists that one element could not be converted into another. Then, in 1896 Henri Becquerel discovered radioactive rays (natural radioactivity) coming from a uranium compound. Ernest Rutherford s study of these rays showed that atoms of one element may indeed be converted into atoms of other elements by spontaneous nuclear disintegrations. Many years later it was shown that nuclear reactions initiated by bombardment of nuclei with accelerated subatomic particles or other nuclei can also transform one element into another—accompanied by the release of radiation (induced radioactivity). 

Atomic theory is central to chemistry. According to this theory, all matter is composed of small particles, or atoms. Each element is composed of the same kind of atom, and a compound is composed of two or more elements chemically combined in fixed proportions. A chemical reaction consists of the rearrangement of the atoms present in the reacting substances to give new chemical combinations present in the substances formed by the reaction. Although Dalton considered atoms to be the ultimate particles of matter, we now know that atoms themselves have structure. An atom has a nucleus and electrons. These atomic particles were discovered by J. J. Thomson and Ernest Rutherford. 

Rutherfordium - the atomic number is 104 and the chemical symbol is Rf. The name derives from the English physicist Ernest Rutherford who won the Nobel prize for developing the theory of radioactive transformations. Credit for the first synthesis of this element is jointly shared by American scientists at the University of California lab in Berkeley, California under Albert Ghiorso and by Russian scientists at the JINR (Joint Institute for Nuclear Reactions) lab in Dubna, Russia under Georgi N. Flerov. The longest half-life associated with this unstable element is 10 minute Rf. 

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. 

The idea of energy quantization weis brought into chemistry with the application of quantum theory to the electronic structure of atoms in 1913 by the Danish physicist Niels Bohr (1885-1962, 1922 Nobel laureate in Physics). At the time, Bohr was working in the laboratory of the New Zealand physidst Ernest Rutherford (1871-1937, 1909 Nobel laureate in Chemistry) in England, a short time after the nuclear structure for the atom had been established by Rutherford and his co-workers. Classical electromagnetic theory predicted that the electrons around the nucleus. 

Speculations about the nature of matter date back to ancient Greek philosophers like Thales, who lived in the sixth century b.c.e., and Democritus, who lived in the fifth century b.c.e., and to whom we credit the first theory of atoms. It has taken two and a half millennia for natural philosophers and, more recently, for chemists and physicists to arrive at a modern understanding of the nature of elements and compounds. By the 19th century, chemists such as John Dalton of England had learned to define elements as pure substances that contain only one kind of atom. It took scientists like the British physicists Joseph John Thomson and Ernest Rutherford in the early years of the 20th century, however, to demonstrate what atoms are—entities composed of even smaller and more elementary particles called protons, neutrons, and electrons. These particles give atoms their properties and, in turn, give elements their physical and chemical properties. 

The dualistic theory of chemical combination proposed by Davy and Berzelius, although it is not as simply and widely applicable as they had hoped, explains quite successfully in a qualitative way the formation of chemical compounds by atomic species from opposite sides of the periodic table. At the turn of the century, even before Ernest Rutherford developed the picture of the planetary atom, J. J. Thomson had suggested that the electrons are arranged in groups or layers in an atom, and that the number of electrons in the outermost layer largely determines the chemical properties of the species. 

Being the simplest form of matter, since each atom or molecule is independent, and not affected by forces due to the other atoms, a gas therefore made an ideal candidate for studying line spectra. The hydrogen atom being the simplest atom—as revealed from the chemical experiments and observations of Dalton, Avogadro, Joseph-Louis Gay-Lussac, and others (described below)—was therefore chosen, and its line spectrum carefully studied. Between the years 1909 and 1912, the first successful theory of the hydrogen atom, and its line spectrum, was formulated, based on the experimental work of Ernest Rutherford and the theoretical insights of Niels Bohr. ... 

In 1898, in Cambridge, England, a New Zealander, Ernest Rutherford, demonstrated that there were at least two different types of radiation with different penetrating power. He called these alpha and beta radiation. He subsequentiy worked at McGill University in Montreal, Canada, and found more radioactive elements different types of radium and thorium, and actinium. He proposed that these were links in chains of radioactive materials, called the transformation theory. Rutherford and his colleague, Frederic Soddy, described that the rate of decay of radioactive elements were characteristic of the element, and came to be known as half-life. Decay follows the law of probability. Over a given period of time, each atom has a certain probability of decaying, a process that results from the random movements of the subatomic components of the radioactive atoms. This was the first instance in physics of a truly unpredictable phenomenon. The decay of a radioactive atom was probabilistic. 

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