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500
Democritus
Democtritus lived in the ancient Greek times at around 500 B.C
What- He said that atoms can't be destroyed and only differ in shape, position, and arrangement. How- His mentor Leucippus made an atomic theory and Democritus continued his work. -
500
Aristotle
He lived around 500 B.C
What- He believed that everything was made of fire, water, air, and earth. He also believed that there was not a limit to how much times matter could be divided. How- He came up with these by himself. No experiment. -
John Dalton
What- His theory was that matter is made up of atoms, individual particles. How- Dalton studied the behavior of gases and made wooden spheres to represent the atoms of different elements. -
J.J. Thomson
What- He discovered subtomic particles, which are smaller than atoms. He also found out that an atom is neutral.
How- He had a glass tube, most of the air was removed. It had a metal disk at each end, wires were connected to the metal disks and when the current was turned on, one disk became negatively charged and the other was positively charged. -
Hantaro Nagaoka
What- He created an early incorrect model of an atom. How- He used an analogy based on Saturn's rings. He used the Saturnian model and worked on spectroscopy. -
Robert Andrews Millikan
What- He measured the charge of an electron. How- Millikan used an oil drop experiment. -
Ernest Rutherford
What- He discovered the atomic nucleus. How- He measured the deflection of alpha particles by aiming a beam of alpha particles at gold foil. -
Niels Bohr
What- He contributed that electron clouds orbit the nucleus of the atom. How- He used Rutherfor's experiment and also worked with Rutherford. -
Erwin Shrodinger
What- Discovered that electrons are really waves. He also found that atoms have a positively charged nucleus that is surrounded by negatively charged electrons.
How- He used Bohr's model, and Brogile's concept. -
Henry Moseley
What- Moseley determined the number of positive charges in the nucleus of an atom. How- He studied under Rutherford. He also used x-rays, that he developed, to study the structure of an atom. -
Ernest Marsden
What- Said there was different types of atoms with specific properties.
How- He used fire, water, air and earth diagram to show dividings. -
James Chadwick
What- Discovered the neutron. How- He smashed alpha particles into beryllium and allowed released radiation to hit paraffin wax. -
Louis de Brogile
What- Louis de Brogile contributed that moving particles like electrons also have some waves. How- He used others' experiments. He added his own thought.
