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460 BCE
Democritus
He was born in 460 B.C. in Thrace and died in 370 B.C. He discovered that everything was made up of atoms and that they were indestructible. He was known as the “Laughing Philosopher” because he was often cheerful at work. -
460 BCE
Democritus Model
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John Dalton
He was born September 6, 1776, in Cumberland, England and died July 21, 1884, in Manchester, England. He proposed that all matter is made of atoms and all atoms are identical. He came upon this knowledge by experiments using gases. John Dalton also researched color blindness and determined the cause of red-green colorblindness. -
J.J. Thomson
Born in 1856 in Cheetham Hill, England and died in 1940. He discovered the electron by an experiment with cathode rays that he determined to be negatively charged. This led to the development of of The Plum Pudding model which contained electrons. He published 200 papers and 13 books and was awarded the Nobel Peace Prize in 1906. He was also knighted in 1908 by king Edward VII -
Cathode Ray Experiment
J.J. Thomson conducted an experiment called the cathode ray experiment in which they constructed a glass tube with wires inserted on both ends. As they pumped out air and electric charge would pass across the tube from the wires and create and fluorescent glow. This was known as a cathode ray and later known as and electron gun. -
Plum Pudding Model
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Robert Millikan
He was born on March 22, 1868, in Illinois and died on December 19, 1953, in California. He discovered the value of the electric charge through the oil drop experiment. He was awarded the Nobel Peace Prize in 1923 for his work in physics. He married Greta Erwin Blanchard and has 3 sons -
Ernest Rutherford
He lived from 1871 to 1937 in Spring Grove, New Zealand. He was the first to discover the atom had a small nucleus that is circled by electrons. He discovered this by the Gold Foil experiment in 1908. This led to the development of the Rutherford Model. He was also awarded the Nobel Peace Prize in 1908 for his theory of atomic structure. He was the first person from Oceania to receive a Nobel Peace Prize. He was also the youngest of 12 siblings. -
Rutherford Model
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Neils Bohr
Neils Bohr was born on October 7, 1885, in Copenhagen, Denmark and died on November 18, 1962. He proposed that electrons move around the nucleus but only in fixed orbits. He also had a theory that the hydrogen atom based on quantum theory that energy is transferred only in specific quantities. He was nominated for the Nobel Peace Prize 3 times in 2 years but never won. He also studied under J.J. Thomson but disagreed with the Plum Pudding model. -
Bohr Model
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Erwin Schrodinger
He lived in Vienna, Austria from his birth on august 12, 1887 till his death on January 4, 1962. Erwin created a model of the atom that combined equations to find a model for the distribution of the electrons in an atom. He was awarded the Nobel Peace Prize in physics in 1933. -
James Chadwick
He was born in Cheshire, England in 1891 and died July 24, 1974. He made the discovery of the existence of neutrons. He based his experiments on information he was researching on in World war 1 and discovered the neutron trying to split the atom. He was knighted in 1945 and received many medals during his career. He also had twin daughters named Joanna and Judith. -
Gold Foil Experiment
Ernest rutherford performed an experiment in which he shot a beam of alpha particles at a sheet of gold foil. When he did this, a few of the particles were deflected and he concluded that a nucleus was the cause of the deflection. -
Oil Drop Experiment
Robert Milikan conducted an experiment in which he suspended two small charged drops of oil in between two metal electrodes by balancing downward gravitational force with electric forces and upward drag
