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400
Democritus 400 B.C.
Democritus was a Greek Philosopher from around 400 B.C. Democritus is credited for coming up with the original model of the atom. He originated the thought that atoms are indestructable and indivisible. However, this idea was not supported by scientific evidence. -
Robert Boyle
Boyle proposed that elements are composed of 'corpuscles' of various types and sizes that are able to organize themselves into groups that represent different chemical substances. He also was able to distinguish between a mixture and a compound. He is primarely known for Boyle's law which describes the inversely proportional relationship between the absolute pressure and volume of a gas. -
Antoine Lavoiser
Antioinen Lavoiser in mainly known for his discovery of combustion in 1772. He was the the most significant contributor the discovery of combustion. In his first experiments he reported that when he burned phosphorus, it combined with a large quantity of air to produce acid spirit of phosphorus, and that the phosphorus increased in weight whenit was burning. -
John Dalton
John dalton proposed another atomic theory in 1803. In his theory he said that all elements are made out of atoms, atoms of specific elements are identical in size and mass and have the same properties, atoms can not be destroyed, atoms of different elements combine into whole numbers to form chemical compounds, atoms are invisible and atoms are combined, rearranged, and separated in chemical reactions. This theory survived and was very important in the future of science. -
Dmitri Mendeleev
Mendeleev is known for his work on the Periodic Law and the first Periodic table. In 1869 he created the first Periodic Table. The Periodic Law states that when elements are arranged according to their atomic number, elements with similar properties will appear at regular intervals. -
JJ Thomson - Electrons
J.J. Thompson discovered electron in 1897. Other scientists had already sudgested that atoms had been made up of a more fundamental unit. He was the first person to sudgest that the fundamental unit was 1000 times smaller than the atom itself. He also came up with the plum pudding model which was a sphere with a positively charged base with negative charges floting around the base. However it was later found to be inacurate. -
Max Planck
Max Planck introduced quantum theory, stating that electromagnetic energy could only be emitted in quantized form. His quanta are now called photons by physicists. -
Robert Milikan
Mendeleev is known for his work on the Periodic Law and creation of the first Periodic table. In 1869 he created the first Periodic Table. The Periodic Law states that when elements are arranged according to their atomic number, elements with similar properties will appear at regular intervals. -
Ernest Ruthford
Ernest Ruthford discovered the proton in 1917. The proton makes up part of an atoms nucleus. A proton has the same amount of charge of a electon but is positive, not negative. He also cunducted the gold foil experiment. To do this, he shot alpha particles off of gold foil. Most of the particles went through but few were deflected. Created Ruthefords atomic model. -
Niels Bohr
Neils Bohr developed the Bohr atomic model, with electrons orbiting around the nucleus, and chemical properties being determined by how many electrons are in the outer orbits. He also created the Planck quantum theory, stating that when electrons change orbits they emit a quantum of discrete energy. -
Henry Mosely
He invented the idea of the atomic number and created moseley's law. The atomic number is the number of protons in th enucleus of an atom of an element and identifies an element. Moseley's law justified many concepts by sorting the elements of the periodic table of the elements in a quite logical order based on their physics. -
Erwin Schrodinger
Erwin Shrodinger described how electrons move in wave form, and developed the Schrodinger equation which describes how the quantum state of a system changes with time. -
James Chadwick - Nuetron
James Chadwig discovered the nuetron in 1932. A nuetron is a subatomical particle that makes up part of an atom. It doesn't have a positive or negative charge, but it has the same mass as a proton. His discovery was very important when it came to understanding the nucleus.
