Ernest Rutherford grp 6

Ernest Rutherford

Nuclear Model

    Biography and History

     Ernest Rutherford was born at Spring Grove in rural Nelson on August 30th 1871, the second son and fourth child of twelve born to James and Martha Rutherford

      Martha became a teacher at the Spring Grove school where her efforts were always praised by the provincial school inspector. So Ernest Rutherford and his siblings received a good education because of parents who appreciated education: his father because he hadn't had much and his mother because she had.

     Rutherford became popular among professors of different colleges, including those Manchester and Cambridge. He helped define several points and made significant contributions to scientific facts known. He also participated in war work where he contributed several war weapon models, an improvement for the cannon, for instance. Rutherford was knighted in the 1914 New Years Honours list and visited Australia and New Zealand for a scientific meeting and for a family reunion. War was declared just before he reached Australia.

      In 1919 he returned to the Cavendish as Director. Under him, Nobel Prizes were awarded to Chadwick for discovering the neutron (in 1932), Cockcroft and Walton for an experiment which was to be known as splitting the atom using a particle accelerator, and Appleton for demonstrating the existence of the ionosphere. He was admitted to the Order of Merit in 1925 and in 1931 was created Baron Rutherford of Nelson, of Cambridge in the County of Cambridge, a title that became extinct upon his unexpected death in hospital following an operation for an umbilical hernia (1937). Since he was a peer, British protocol at that time required that he be operated on by a titled doctor, and the delay cost him his life. He is interred in Westminster Abbey, alongside J. J. Thomson, and near Sir Isaac Newton.

 Chemical Model

     In it, the atom is made up of a central charge (this is the modern atomic nucleus, though Rutherford did not use the term "nucleus" in his paper) surrounded by a cloud of (presumably) orbiting electrons. In this 1911 paper, Rutherford only commits himself to a small central region of very high positive or negative charge in the atom.

    The Rutherford paper suggested that the central charge of an atom might be "proportional" to its atomic mass in hydrogen mass units u (roughly 1/2 of it, in Rutherford's model).

Gold Foil Experiment

      Ernest Rutherford publishes his atomic theory describing the atom as having a central positive nucleus surrounded by negative orbiting electrons. This model suggested that most of the mass of the atom was contained in the small nucleus, and that the rest of the atom was mostly empty space. Rutherford came to this conclusion following the results of his famous gold foil experiment. This experiment involved the firing of radioactive particles through minutely thin metal foils (notably gold) and detecting them using screens coated with zinc sulfide (a scintillator). Rutherford found that although the vast majority of particles passed straight through the foil approximately 1 in 8000 were deflected leading him to his theory that most of the atom was made up of 'empty space'.

To find out more about Ernest Rutherford:

Link 1

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"If your result needs a statistician then you should design a better experiment."

— Ernest Rutherford

 

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Early Greek Theories: Democritus and Aristotle

Democritus

Democritus was an Ancient Greek philosopher born in Abdera, Thrace, Greece. He was an influential pre-Socratic philosopher and pupil of Leucippus, who formulated an atomic theory for the cosmos.

At around 400 B.C., Democritus was able to come up with the idea that matter could not be divided indefinitely. He asked this question: If you break a piece of matter in half, and then break it in half again, how many breaks will you have to make before you can break it no further? Democritus thought that it ended at some point, a smallest possible bit of matter. He called these basic matter particles, atoms.

However, Democritus' ideas did not have lasting effects on other Greek philosophers for other Greek philosophers like Aristotle had disagreed with his theories therefore making his theory somewhat unpopular.

Aristotle

Although the idea of the atom, the smallest, indivisible component of matter, was first proposed in 400 BC, Aristotle didn't like it. He claimed that there was no smallest part of matter and that different substances were made up of proportions of fire, air, earth, and water. As there were of course no experimental means available to test either view, Aristotle's prevailed mainly because people liked his philosophy better.

Aristotle’s theory of the basic constituents of matter looks to a modern scientist perhaps something of a backward step from the work of the atomists and Plato. Aristotle assumed all substances to be compounds of four elements: earth, water, air and fire, and each of these to be a combination of two of four opposites, hot and cold, and wet and dry. (Actually, the words he used for wet and dry also have the connotation of softness and hardness).

Aristotle’s whole approach is more in touch with the way things present themselves to the senses, the way things really seem to be, as opposed to abstract geometric considerations. Hot and cold, wet and dry are qualities immediately apparent to anyone, this seems a very natural way to describe phenomena. He probably thought that the Platonic approach in terms of abstract concepts, which do not seem to relate to our physical senses but to our reason, was a completely wrongheaded way to go about the problem. It has turned out, centuries later, that the atomic and mathematical approach was on the right track after all, but at the time, and in fact until relatively recently, Aristotle seemed a lot closer to reality. He discussed the properties of real substances in terms of their “elemental” composition at great length, how they reacted to fire or water, how, for example, water evaporates on heating because it goes from cold and wet to hot and wet, becoming air, in his view. Innumerable analyses along these lines of commonly observed phenomena must have made this seem a coherent approach to understanding the natural world.

SOURCES:

• http://galileoandeinstein.physics.virginia.edu/lectures/aristot2.html
• http://improbable.org/era/physics/atom.html
• http://en.wikipedia.org/wiki/Democritus

made with love by Group 1 Justine Basco Rianna Cruz Bianca Hilario April Ocampo

Who be trippin with our layout? /:)

SRSLY.

The Awesome Niels Bohr

Niels Bohr (7 October 1885 – 18 November 1962) was a Danish physicist who contributed to the understanding of atomic structure. He won the Nobel Physics Prize in 1922. He was a consultant for a to-secret laboratory for a project that concerned nuclear arms race. He is also known as the Father of Quantum Theory.

Planetary Orbit Model

The Bohr model depcts the atom as small having a positively charged nucleus surrounded by electrons that travel in orbit, similar to the solar system structure. Orbits or energy levels are located at certain distances from the nucleus. The shell of the atom, where the chemical properties of an element are determined by the electrons in the outermost orbit.

Double Slit Experiment

A double-slit apparatus suggested by Niels Bohr to demonstrate the wave-particle dualism.

To know about Niels Bohr, click here to watch a video.

Group 7

Bacar

Golloso

Legaspi

Nuguid

Proust's Law On Definite Proportions

Joseph Louis Proust

He became known by his research work on the steadiness of composition of chemical compounds

(aka Law of Definite Proportion).

Personal Life

September 26, 1754 – July 5, 1826 (Angers, France)

Proust's Father was a pharmaceutic. He Studied chemistry in his father’s shop and later came to Paris where he gained the appointment of apothecary in chief to the Salpetriere. He too, was chief- pharmaceutic in Salpetrière by the time he became interested in ascension balloons. He also taught chemistry with Pilâtre de Rozier, a famous astronaut. He taught at the Chemistry School in Segovia and at the University of Salamanca, in Spain.

Joseph Proust was appointed to the Royal Laboratory in Madrid under the influence of Carlos IV. After Napoleon Bonaparte invaded Spain, he returned to France.

Achievements in Chemistry

Proust disproved chemist Berthollet with a new law, the Law Of Definite Proportions (a.ka. Proust's law). He performed series of researches which characterize different types of sugars, present in vegetable products.

Law of Definite Proportions and Elements

Also known as the ‘Proust’s Law’

This law states that a chemical compound always contains exactly the same proportion of elements by mass.

An equivalent statement is the law of constant composition, which states that all samples of a given chemical compound have the same elemental composition. Along with the law of multiple proportions by John Dalton, which states that when chemical elements combine they do so in a ratio of small whole numbers, the law of definite proportions forms the basis of stoichiometry.

 History of the Law of Definite Proportions and Elements

At the end of the 18th century, when the concept of a chemical compound had not yet been fully developed, the law was novel.

In fact, when first proposed, it was a controversial statement and was opposed by other chemists, most notably Proust's fellow Frenchman Claude Louis Berthollet, who argued that the elements could combine in any proportion. The very existence of this debate underscores that at the time, the distinction between pure chemical compounds and mixtures had not yet been fully developed.

The law of definite proportions contributed to, and was placed on a firm theoretical basis by, the atomic theory that John Dalton promoted beginning in 1803, which explained matter as consisting of discrete atoms, that there was one type of atom for each element, and that the compounds were made of combinations of different types of atoms in fixed proportions.

More on the Law of Definite Proportions

Proust studied copper carbonate, the two tin oxides,and the two iron sulfides to prove this law. He did this by making artificial copper carbonate and comparing it to natural copper carbonate. With this he showed that each had the same proportion of weights between the three elements involved (Cu, C, O). Between the two types of the other compounds, Proust showed that no intermediate indeterminate compounds exist between them. Proust published this paper in 1794, but the law was not accepted until 1811, when the Swedish chemist Jöns Jacob Berzelius gave him credit for it.

There are, however, exceptions to the Law of Definite Proportions. An entire class of substances does not follow this rule. The compounds are called non-stoichiometric compounds, or Berthollides, after Berthollet. The ratio of the elements present in the compound can fluctuate within certain limits, such as in the example of Ferrous oxide. The ideal formula is FeO, but due to crystallographic vacancies it is reduced to about Fe0.95O

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John Dalton: He Got the Ball Rolling

JOHN DALTON

John Dalton was born in Eaglesfield, Cumberland, England on September 6, 1766. He was a famous chemist, meteorologist and physicist. Dalton is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness (sometimes referred to as Daltonism, in his honor). John Dalton was one of the first scientists to decide that all matter is made up of small particles, or atoms. Around 1790, Dalton seems to have considered taking up law or medicine, but his projects were not met with encouragement from his relatives — Dissenters were barred from attending or teaching at English universities — and he remained at Kendal until, in the spring of 1793, he moved to Manchester. Also, Dalton was an appointed teacher of mathematics and natural philosophy at the "New College" in Manchester, a Dissenting academy until 1800, and published a book entitled "Elements of English Grammar" in 1801.

      In 1800, Dalton became a secretary of the Manchester Literary and Philosophical Society, and in the following year he orally presented an important series of papers, entitled "Experimental Essays" on the constitution of mixed gases; on the pressure of steam and other vapours at different temperatures, both in a vacuum and in air; on evaporation; and on the thermal expansion of gases. These four essays were published in the Memoirs of the Lit & Phil in 1802. Dalton proceeded to print his first published table of relative atomic weights. Six elements appear in this table, namely hydrogen, oxygen, nitrogen, carbon, sulfur, and phosphorus, with the atom of hydrogen conventionally assumed to weigh 1. Dalton provided no indication in this first paper how he had arrived at these numbers. However, in his laboratory notebook under the date 6 September 1803[4] there appears a list in which he sets out the relative weights of the atoms of a number of elements, derived from analysis of water, ammonia, carbon dioxide, etc. by chemists of the time. He died on July 27, 1844 due to a stroke.

Billiard Ball Model

There were FIVE Main Points on Dalton's Atomic Theory:

• Chemical elements are made of atoms
• The atoms of an element are identical in their masses
• Atoms of different elements have different masses
• Atoms only combine in small, whole, number ratios
• Atoms can neither be created nor destroyed

** The balls in the figure were used by Dalton in his experiments.

Events during Dalton's time (1766-1844)

• American Revolutionary War
• Decleration of Independence in the United States of America
• First European establishment in Australia at Sydney
• George Washington is elected as president
• French Revloution
• Bifocals were invented by Benjamin Franklin
• Antoine Lavoisier discovers the law of conservation of mass, the basis of chemistry, and begins modern chemistry

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J. J Thomson

J. J Thomson's father died when he was only sixteen years old. He studied in Owens College, Manchester. He was encouraged by his professor to take up a scholarship in Trinity College. He topped second in his class in the year 1880 next to Joseph Larman. Trinity gave him a fellowship and he stayed while trying to craft models to reveal the nature of atoms and electromagnetic forces. In the year 1884, He was recruited in the Cavendish Laboratory. He was the third Cavendish professor there. He was one of the most accomplished physicists of his era. In the year 1906, He was awarded the Nobel Prize in Physics for his researches in the discharge of electricity in gases. In 1918, he was chosen the master of his old college, Trinity. A year later, he resigned from his professorship in Cavendish.

Category: British physicist and Nobel laureate

Date of birth: December 18, 1856

Date of death: August 30, 1940
Wife: Miss Rose Paget

Profession: Physicist, Mathematician

Works written: Electricity and matter, ...

Awards and recognition

Royal Medal (1894)

Hughes Medal (1902)

Nobel Prize for Physics (1906)

Elliott Cresson Medal (1910)

Copley Medal (1914)

Franklin Medal (1922)

THOMSON'S CATHODE RAY EXPERIMENT

J. J Thomson was one of the great scientists of the 19th century; his inspired and innovative cathode ray experiment greatly contributed to our understanding of the modern world.

CATHODE RAY TUBE
it is a glass tube with wires inserted at both ends. It pumps out as much of the air as they couds and the electric charge passed across the tube would create a flourescent glow. Its commonly seen as the glowing neon sign on any "old fashioned" television.

JJ THOMSONS CAHTODE RAY: SECOND EXPERIMENT

He had to construct a slightly different cathode ray tube. He attempted to deflect the rays with an electric field. Later on, he proved that the rays were delfected by the electric charge. Thus, it carried a negative charge.

JJ THOMSONS CATHODE RAY: THIRD EXPERIMENT

Thomson found out the charge ratio was so high that the particles either carried a huge charge or a thousand times smaller than a hydrogen ion.

To know more about J.J Thomson and his works, visit

http://www.kentchemistry.com/links/AtomicStructure/JJThompson.htm