Atomic Theory Scientists
1.
Democritus- Discovered matter was made up of particles called atoms- about 400 B.C.
2.
John Dalton (1808)- 6 Postulates
 Matter made up of tiny, indivisible particles called atoms

Atoms of an element are identical with the same properties

Atoms can’t be created, destroyed or divided
 Atoms of different atoms combine to form chemical compounds in simple whole number ratios.

In a chemical reaction, atoms are separated, combined or rearranged.

Atoms cannot be changed into atoms of another element
Postulate proved wrong- 1 st one- atoms are now known to be divisible- protons, neutrons, electrons.
3.
J.J. Thomson (1897)- Cathode Ray-tube experiment, discovered the electron,, plum pudding model
4.
Ernest Rutherford (1911)- Gold Foil Experiment, discovered the nucleus and proton, found atoms are most empty space with a dense positive nucleus, Solar System or Planetary Model
5.
James Chadwick- Discovered the neutron
6.
Neils Bohr(1913)- Electrons orbit in a circular pattern around the nucleus in fixed energy levels, Bohr’s Atomic model
7.
Irwin Schrodinger(1926)- Developed the electron cloud model, electrons move throughout atom in random paths, still the current atomic model
Atomic Theory Scientists
1. .Democritus- Discovered matter was made up of particles called atoms- about 400 B.C.
2. John Dalton (1808)- 6 Postulates

Matter made up of tiny, indivisible particles called atoms
 Atoms of an element are identical with the same properties

Atoms can’t be created, destroyed or divided

Atoms of different atoms combine to form chemical compounds in simple whole number ratios.
 In a chemical reaction, atoms are separated, combined or rearranged.
 Atoms cannot be changed into atoms of another element
Postulate proved wrong- 1 st one- atoms are now known to be divisible- protons, neutrons, electrons.
3.
.J.J. Thomson (1897)- Cathode Ray-tube experiment, discovered the electron, plum pudding model
4.
Ernest Rutherford (1911)- Gold Foil Experiment, discovered the nucleus and proton, found atoms are most empty space with a dense positive nucleus, Solar System or Planetary Model
5.
James Chadwick- Discovered the neutron
6.
Neils Bohr (1913)- Electrons orbit in a circular pattern around the nucleus in fixed energy levels, Bohr’s Atomic Model
7.
Irwin Schrodinger (1926)- Developed the electron cloud model, electrons move throughout atom in random paths, still the current atomic model