-
465 BCE
Democritus
Theory: All matter is made up of invisible particles, all atoms are indestructible, atoms are solid but invisible, atoms differ in size, shape and arrangement. -
John Dalton
A given compound always contains the same proportions of the elements.
Most natural materials are mixtures of pure substances.
Pure substances are either elements or combination of elements called compounds. -
Daltons atomic theory
Dalton's Atomic Theory:
- All matter is made of atoms. Atoms cant be split and indestructible.
- All atoms of a given element are identical in mass and properties
- Compounds are formed by a combination of two or more different kinds of atoms.
- A chemical reaction is a rearrangement of atoms. -
J.J. Thompson
Discovered the electrodes by studying the glowing beams of light that electrodes give off. -
Cathode ray tube
A small vacuum tube that uses electron guns to send images showing electron beams around an atom. -
Plum Pudding Atomic Model
Shows the electrons being small balls in a liquid substance as the nucleaus -
Antoine Lavoisier
Learned that mass was neither destroyed or created in chemical in chemical reactions and is now known as the conversion of mass. The conversion of mass is that mass is never destroyed or created it is that it is converted into a different substance. -
Robert millikan
Invented the oil drop experiment that shows the electric charge in an electron -
Gold Foil Experiment
This experiment was conducted to test if the middle of an atom, the nucleus was soft. Ernest Rutherford, the first to try this experiment took a sheet of gold foil and shot at it.
Thinking the main mass of the atom was soft and squishy, he thought it would go through. But it bounced back at him. which showed that there is something solid in the middle of an atom -
rutherford model
The Rutherford model was similar to the plum pudding model as it had electrons floating around freely but instead of the nucleus not being solid it was a small solid nucleus in the middle -
Ernest Rutherford
Invented the Rutherford model -
bohr planetary model
A diagram showing the electrons floating in orbit around the nucleus like the planets orbiting the sun. -
Niels Bohr
Created the bohr model after learning about how the nucleus was solid -
Quantum mechanical model
Shows the electrons orbiting around and through the atom and having a specific path that it follows -
James Chadwick
Discovered the nucleus and neutron and how they are connected -
Electron cloud
A model that shows the exact position of an electron around an atom
