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100
Aristotle
He further classified animals into species based on those that had red blood and those that did not. Aristotle identified the water cycle and discussed topics ranging from natural disasters to important events. Although many of his views on the Earth were controversial at the time, they were readopted during the late Middle Ages -
100
Democritis
Democratis found out that all matter consists of invisible particles called atoms, atoms are indestructible, atoms are solid but invisible, atoms are homogenous, atoms differ in size, shape, mass, position, and arrangement, solids are made of small, pointy atoms.
->Liquids are made of large, round atoms. -
100
Leucippus
He said that there could be no motion if there was no void, and he inferred that it was wrong to identify the void with the non-existent. -
Antoine Lavoiser
Antoine named the elements carbon, hydrogen and oxygen; discovered oxygen’s role in respiration; established that water is a compound of hydrogen and oxygen; discovered that sulfur is an element, and helped continue the transformation of chemistry from a qualitative science into a quantitative one. -
John Dalton
John Dalton was born color blind so he was very interested in researching color blindness. Dalton came up with a law:Explained that the repelling forces previously believed to create pressure only acted between atoms of the same sort, and that the atoms within a mixture varied in weight and complexity. Not many scientist believed him. Dalton's theory additionally examined the compositions of compounds, explaining that the tiny particles (atoms) in a compound were compound atoms. -
Joseph Proust
Proust stated the Law of Definite Proportions. The law states that the ratio of elements in a compound is always the same/constant. He also hinted at the 'lego'ness of matter; he believed that matter could be put together in certain patterns to make bigger, different, unique matter -
William Crookes
He demonstrated that cathode rays travel in straight lines and produce phosphorescence and heat when they strike certain materials. He invented many devices to study the behaviour of cathode rays, but his theory of radiant matter, or a fourth state of matter, proved incorrect in many respects. -
Dmitri Mendeleev
Mendeleev created the periodic table. Mendeleev’s periodic table was based on atomic weights and he watched as the conference produced an agreed, standardized method for determining these weights. The periodic table is still being used today in classrooms. -
JJ Thomson
JJ Thomson said that electricity is trasmitted by a tiny particle. In the 1890s, J.J. Thomson managed to estimate its magnitude by performing experiments with charged particles in gases. In 1897 he showed that cathode rays (radiation emitted when a voltage is applied between two metal plates inside a glass tube filled with low-pressure gas) consist of particles - electrons - that conduct electricity. Thomson also concluded that electrons are part of atoms. -
Ernest Rutherford
Ernest worked jointly with Thomson on the behaviour of the ions observed in gases which had been treated with X-rays, and also, in 1897, on the mobility of ions in relation to the strength of the electric field, and on related topics such as the photoelectric effect. In 1898 he reported the existence of alpha and beta rays in uranium radiation and indicated some of their properties. He worked mainly on radioactive rays. -
Louis Debroglie
He studied the wave nature of electrons and suggested that all matter has wave properties. This concept is known as the de Broglie hypothesis -
Henry Moseley
By generating voltages on a radioactive source, Moseley actually created the world’s first atomic battery – a beta cell. He called it a radium battery.Now atomic batteries are used where long battery life is needed, like in spacecrafts. -
Erwin Schrodinger
In Niels Bohr's theory of the atom, the electrons absorb and emit radiation of fixed wavelengths when jumping between the fixed orbits around a nucleus. The theory gave a good description of the spectrum from the hydrogen atom, but must be further developed for more complicated atoms and molecules. Assuming that matter, e.g. electrons, could be regarded both as particles and as waves, Erwin Schrödinger formulated in 1926 a wave-equation that accurately gave the energy levels of atoms. -
Niels Bohr
The discoveries of the electron and radioactivity at the end of the 19th century led to different models for the structure of the atom. In 1913, Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted. Bohr's theory could explain why atoms emitted light in -
Werner Heisenberg
Werner created the uncertainty prinicple: "The more precisely the position is determined, the less precisely the momentum is known" -
James Chadwick
James is most famous for his finding of the neutron. James predicted the atom would have a neutron, he established that atomic number is determined by the numbers of protons in an atom, he also discovered the fourth subatomic particle,the neutron. -
Murray Gell-Mann
He showed scientists what makes up protons and neutrons, he discovered the quark. A quark is a fast moving point of energy and every proton and neutron contains three. There are two types of quarks within the neutron and proton, up quarks and down quarks
