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Transcript of Time Line
His theory: Matter could not be divided into smaller pieces forever, eventually the smallest possible piece would be obtained. This piece would be indivisible. He named the smallest piece of matter atoms, meaning not to be cut.
He discovered that atoms are homogenous, solids are made of small atoms, liquids are made of big, round atoms, and oils are made of fine, and small atoms that can slip past each other.
He gave an image of an atom that by their shape, size, and the arrangement of their parts. These connections were explained by material links and single atoms were supplied with attachments: with hooks, eyes, some with balls and sockets.
Democritus was an ancient Greek philosopher. He what is thought to be the first atomic theory. Some people consider him to be the father of modern science.
There are elements, which is put in Aristotle’s theory. his theory did help the atomic theory in a bad way. Aristotle discovered a lot on many areas of science, leading to ideas causing some of the greatest progresses in science and ideas that lead to a big barrier in science.
Dalton believed that all matter is made up of very small particles called atoms, of a given element, atoms are the same size, mass, and other properties. He said that atoms cannot be divided, created, or destroyed. Atoms of different elements combine in simple whole number ratio to form chemical compounds which means you can't split an atom. In chemical reactions atoms are combined, separated or rearranged.
Dalton's model to represent an atom, he used a billiard ball to show how atoms are solid, indestructible spheres because they are made up with protons, which have a positive charge, neutrons, which have a negative charge, and electrons, which are neutral.
Dalton's interest in atmospheric pressures eventually took him to a closer look at gases. When he was studying the nature and chemicals in the air in the 1800s, Dalton learned that it was not a chemical solvent, what other scientists believed. It was a mechanical system composed of small individual particles that used pressure by each gas independently.
Dalton's experiments on gases led to his discovery that the pressure of a mixture of gases amounted to the sum of the pressures that each gas made while taking up the same space.
Dalton's fascination with gases gradually led him to formally assert that every form of matter (whether solid, liquid or gas) was also made up of small individual particles. Dalton told his belief that atoms of different elements could be distinguished based on their different weights. In so doing, he was the first scientist to explain the actions of atoms in terms of the measurement of weight. He also discovered the fact that atoms couldn't be created or destroyed.
Joseph John Thomson
J.J. Thomson discovered the electron through a lot of experiments made to study what electricity gives off in a device called the cathode-ray tube, a area being studied by a lot of scientists at the time. Thomson said that the deflection of the rays by electrically charged plates and magnets as evidence of quotbodies much smaller than atoms& quotbodies that he calculated that it had a very big value for the charge-to-mass ratio. Later he estimated the value of the charge itself.
He devised better methods than before. When he passed the rays through the cathode ray tube, he measured the angle they were deflected. He discovered that the ratio was the same no mater what type of gas it was, which taught him that the particles that made up gas were universal. Thomson determined that all matter is made up of tiny particles that are a lot smaller than atoms. He called these particles 'corpuscles,' at first, although they are now called electrons.
In 1906, he began studying positively charged rays. This led him to when he put a stream of ionized neon through a magnetic and an electric field and used deflection to measure the charge to mass ratio. while doing it, he discovered that neon was composed of two different kinds of atoms and proved the existence of isotopes.
When he put the gas under the low pressure glass tube, a current passed through it the opposite side of the cathode glowed because of a stream of particles named the cathode ray, which proved that it was negatively charged.
Ernest Rutherford discovered the nucleus by shooting a laser with positive charged particles into a gold foil surrounded by a detecting screen. He assumed that the change and mass were evenly distributed throughout the atoms of the gold foil just like the plum pudding model from J.J.
Thomson. When he was looking at the wide angle deflections he found that 1 in 8,000 alpha particles would bounce back. He found out that the particle that made the alpha particle bounce back must be tightly packed. He named this particle the nucleus.
He demonstrated radioactivity was the spontaneous disintegration of atoms and was the first person to artificially disintegrate an element. He considered alpha particles as
helium nuclei. While he was researching, he invented a new kind of radio reciever. He was taught by J.J. Thomson
Rutherford's gold foil experiment helped describe the nuclear structure of the atom. The deflection of the alpha particles implied the existence of a dense, positively charged central region containing most of the atomic mass. He hypothesized the existence of the neutron. J.J. Thomson had already discovered
that electrons are present in an atom and that they are negatively charged. So it was assumed that since an atom is neutral and electrons present are negatively charged, there should be some positive charge inside it that makes it neutral.
He said that energy levels mean that only electrons can exist in specific energy states. He discovered that electrons move in circular orbits within specific energy levels.
Niels Bohr made his model, and called it the Planetary model because it shows the electrons are orbiting around the nucleus just like the planets in our planetary orbit circles the sun. The elctrons only move/orbit on prescribed orbits.
He began to work on the problem of the atom's structure. Ernest Rutherford had said that the atom had a miniature and dense nucleus, surrounded by a cloud of nearly weightless electrons. If the atom took in any energy, the electron jumped to a level further from the nucleus; if it radiated energy, it fell to a level closer to the nucleus. He received the Nobel Prize for this work in 1922
Schrodinger Studied Quantum mechanics and discovered that electrons can only exist in specified energy states. He created the Schrodinger equation of the doppler effect, based on the hypothesis of light and considerations of energy and momentum. He liked the idea of
his teacher on the nature of the conservation laws, so he worked on the articles of Bohr, Kramers, and Slater, which suggested the possibility of violation of these laws in individual atomic processes like radiation.
Just like Niels Bohr, he said electrons can only exist in energy states. His model was the electron cloud, which is orbital, like Bohr's planetary model. The region around the nucleus are hwere electrons are most likely to be found.
In his electron cloud model, he discovered that it is impossible to determine the exact location of an electron. The probability location of an electron is how much energy that electron has. Electrons with the lowest energy are found in the energy level closest to the nucleus and electrons with the highest energy are found in t outermost energy level farthest from the nucleus.
Edwin Schrodinger stated that rather than electrons being distributed within an electron configuration of shells and energy levels, they were arranged in orbitals which were systematically distributed within Electron Clouds. Also known as the region of space that surrounds a nucleus in which two electrons may randomly move. Electrons are constantly moving, it was clear that electrons could not be correctly given a definite moving, it was clear that electrons could not be correctly given a definite position.
James Chadwick discovered neutrons which are the neutral particle in the atom. He predicted that the atoms would have a neutron. He said that the atomic number is how many protons an atom has in it.
Chadwick has had many papers published in college on the topic of radioactivity and connected problems. Neutrons help stabilize the protons in the atom's nucleus because the nucleus is so tightly packed together, the positively charged protons would repel each other normally. Neutrons help to reduce the repulsion between protons and stabilize the atom's nucleus.
He believed in an indivisible particle, named it the atom and thought they looked like different shapes and sizes and were too small to see with the naked eye.
Most people followed his idea, making Democritus’ idea which was that all substances on Earth where made of small particles called atoms to be over looked for almost 2,000 years. Aristotle's view was finally proven incorrect and his teachings are not present in the view today of the atom.
Aristotle did not believe in the atomic theory He thought that all materials on Earth were not made of atoms, but of the four elements, Earth, Fire, Water, and Air. He believed all substances were made of small amounts of these four elements of matter.
He wrote and studied many topics such as ethics, theater, metaphysics, taught Alexander the Great. He did understand much on the world around him. Many say that Aristotle knew everything that was known at the time. He felt that no matter what the number of times you cut a form of matter in half, you would always have a smaller piece of that matter.
Born: 460 BC
Died: 370 BC
Thanks For Watching!
By: Kyleigh Terry P8
Born: 384 BC
Died: 322 BC
Born: December 18th, 1856
Died: August 30th, 1940
Born: August 30, 1871
Died: October 19, 1937
Born: September 6, 1766
Died: July 27, 1844
Born: October 7, 1885
Died: November 18, 1962
When an electron is jumping from one orbit to another with lower energy, a light quantum is emitted. Bohr's theory could explain why atoms let off light in fixed wavelengths.
Born: August 12, 1887
Died: January 4, 1961
"To the electron: may it never be of any use!"
– J.J. Thomson
Ernest Rutherford is known as the 'Father of Nuclear Physics' and considered as one of the greatest experimentalist.
Schrodinger combined the equations for the behavior of waves with a thing called the de Broglie equation to generate a mathematical model for the distribution of electrons in an atom. It consists of wave functions that are the behavior of electrons.
born:October 20th, 1891
died:July 24th, 1974.
Neutrons do not have any electrical charge, they are electrically neutral. When Ernest Rutherford discovered the proton in 1918, scientists at the time might have thought that they had finally figured out atomic structure once and for all. Negatively-charged electrons, orbiting a really small atomic nucleus made up of positively charged protons.