-
500
Democritus
(470- 370 B.C.) The first person to say that matter couldn't divide and coined the term "atomos" which later called the atom. "Atoms cannot be created, destroyed or further divided." He couldn't figure out what held atoms together. -
Aug 25, 600
Aristotle
(384-322 B.C.) At first he didn't agree with Democritus because of his personal ideas about nature, but he ideas were the same as Democritus. -
Period: to
John Dalton
He created the Atomic Theory. He revived the term "atom". "Atoms can be rearranges, seperated or combined to form new things, but cannot be created, destroyed or divided in the process." He took ideas of Democritus and revised them. He proofed the atom. -
Period: to
Sir William Crookes
He noticed a green flash within a cathode ray tube. He discovered the television. -
Period: to
J.J Thompson
He designed a series of CRT experiments at Carrbridge to determine the ratio of the particles charge to its mass. He disproved Dalton's theory that atoms were indivisble. He discovered the eletron. -
Period: to
Robert Millikan
He designed the to determine the charge of the eletron. He determined that the magnitude of the charge was 1.602x10^-19 coulombs. He discovered the mass of the electron. -
Period: to
Ernest Rutherford
He studied how positively charged a-particles interacted with solid matter. He designed an experiment to see if α-particles would be deflected as they passed through a thin sheet of gold foil. He calculated that an atom was mostly just empty space for electrons to move around in. He claimed that it was contained in a tiny region in the center of the atom and called that spot the nucleus. -
Period: to
Ernest Rutherford
Rutherford’s theory explained that the negatively-charged electrons were held within the atom by their attraction to the positively-charged nucleus. His model demonstrates the neutral nature of matter with the balance of positive charges in the nucleus and negative charges of electrons surrounding it. He efined his concept of the nucleus to include that it contained positively charged particles called protons. -
Period: to
James Chadwick
He demonstrated that the nucleus had another neutral subatomic particle, the neutron. -
J.J. Thomson
He received the Nobel Prize for his reasearch which was the discovery of the electron th first subaromic particle. -
James Chadwick
Chadwick won the 1935 Nobel prize for his discovery of the neutron.
