-
Pierre Gassendi
Gassendi revived the atomic theory. He said that atoms are the smallest bodies that can exist. Also, atoms & vacuum, the absolutely full & the absolutely empty, are the only true principle & there is no third principle possible. -
Sir Isaac Newton
Newton modified the amotic theory to atoms as hard particles with forces of attraction between them. -
John Dalton
Dalton's theory has 5 major pionts: 1) All matter is composed of extremely small particles called atoms, which cannot be be subdivided, created, or destroyed. 2) Atoms of a given element are identical in their physical & chemical properties. 3) atoms of different elements differ in their physical and chemical properties. 4) Atoms of different elements combine in simple, whole-numer ratios to form compounds. 5) In chemical reactions, atoms are combined, separated, or rearranged but never changed. -
Sir William Crookes
Sir William Invented a tube where he could see some sort of oarticle beam going from the negative cathode to the positive anode. -
Wilhelm Conrad Roentgen
Discovered x-rays -
J.J. Thompson
J.J. Thompson discovered that electrons were smaller particles of an atom & were negatively charged. -
Robert Millikan
Millikan determined the unit charge of the electron with his oil drop experiment, allowing for the calculation of the mass of the electron & the positively charged atoms. -
Ernest Rutherford
Ernest conducted an experiment to isolated the positive particles in an atom. After this he decided that the atoms were mostly empty space, but had a dense centeral core. -
Niels Bohr
Bohr proposed that electrons traveled in fixed paths around the nucleus. Scientists still use his model to show the number of electrons in each orbit around the nucleus. -
Francis Aston
Invented the mass spectrograph. He was the first person to observe isotopes. -
James Chadwick
James discoverd the neutron. The neutron was a previously unknown particle in the atomic nucles. His discovery was crucial for the fission of uranium 235. -
Leucippus
Timeline index(real time-475 BC)
Leuippus was said to be the first Greek to develop the theory of atomism. Atomism is the idea that everything is composed entirely of various imperishable, indivisible elements called atoms. -
Democritus
Timeline index(Real time-460-370 BC)
Democritus was a student of Leucippus. Democritus took Leucippus work one step further & came up with an atomic teory for the cosmos. His hypothesis on atoms is remarkably similar to modern science's understanding of atomic structure.
