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442 BCE
Democritus
c. 460- c.370 BC, lived in Greek city Abdera, his atomic theory was that small particles are always moving and are interacting through collisions, believed that atoms are indivisible, believed the world was governed entirely by natural laws, his doctrines were an elaborated version of his teachers Leucippus -
John Dalton
1766-1844, lived in England, his theory of partial pressure was based on the idea that like atoms repel and unlike atoms react indifferently toward each other, his argument was that each element had its own kind of atom, he measured the mass of different elements which formulated the Law of Multiple Proportions, he was elected into the fellowship of the Royal Society of London -
J.J Thomson
856-1940, united kingdom, he experimented with cathode ray and discovered the electron, -
Cathode Ray tube experiment:
J.J. Thomson's experiment that showed atoms have electrons. Cathode ray tubes are sealed glass tubes without air. A high voltage is applied across the end of the tube, which caused a beam of particles to flow from the cathode (the negatively-charged electrode) to the anode (the positively-charged electrode), which proved atoms have electrons. -
Gold foil experiment
An experiment by Ernest Rutherford that proved the existence of a nucleus within an atom. He shot a beam of alpha particles at a sheet of gold fuel, a few of the particles were deflected. He concluded that the deflections were caused because of a nucleus. -
Oil Drop Experiment
An experiment done by Robert Millikan that determined the size of the charge on an electron. -
Robert Millikan
1868-1953,united states, he discovered the charge of electrons and how important it was, oil drop experiment- which measured the amount of charge in the electron and also the charge in the electric field. It was used to see electric current and when it was being applied and how it was being charged, he won a Nobel prize for physics -
Ernest Rutherford
1871-1937, lived in England, he discovered that atoms have a nucleus with a small charge and it has a large amount of space around the nucleus and around the empty space is electrons, he made this discovery by using the gold foil experiment to show how the alpha particles affect matter, but he found out how the atom is mostly empty space but has electrons around it and a nucleus. Interesting fact- he invented a detector to receive radio waves
Rutherford model or planetary model -
Neils Bohr
1885-1962, in 1913 he proposed his theory, lived in Copenhagen Denmark, the Bohr model of the atom was the first to incorporate quantum theory, this model describes the properties of atomic electrons in terms of a set of possible values, when the electrons move or jump between allowed or stationary states, the atoms absorb or emit radiation, received the 1922 Nobel Prize in Physics -
Erwin Schrodinger:
1887-1961,lived in Vienna,Austria.Came up with the wave mechanics formula.In 1921 he studied atomic structure and researched quantum statistics in 1924.He noticed how spectral lines formed when light passed through prisms and began experimenting with color and light,and then he came up with the Schrodinger equation.He won the Nobel peace prize and famous for the Schrodinger's cat thought experiment.He also wrote a book about genes and DNA.He had a wife and a mistress, and overall had 3 children. -
James Chadwick
1891-1974,lived in Cheshire,England.Prison of war during WW1 formed a science club with his fellow inmates.First artificial nuclear transformation.In 1932,he began bombarding beryllium with alpha particles which produced an unknown radiation,after many studies and experiments he discovered the neutron. Due to his discovery he was awarded the Hughes Medal of the Royal Society in 1932, and the Nobel Prize for Physics in 1935.He married Aileen Stewart Brown in 1925 and had 2 daughters.
