-
Dalton: Solid Sphere Model
Nickname for his model: Billiard Ball Model
All elements are composed of atoms. It is impossible to divide or destroy an atom
All atoms of the same element are alike
Atoms of different elements are different
Atoms of different elements combine to form a compound. These atoms have to be in definite whole number ratios -
Thompson: The Plum Pudding Model
In 1897 J.J. Thomson discovered the electron, a negatively charged particle more than two thousand times lighter than a hydrogen atom.
Thomson originally believed that the hydrogen atom must be made up of more than two thousand electrons, to account for its mass.
An atom made of thousands of electrons would have a very high, negative electric charge. This was not observed, as atoms are usually uncharged. In 1906 Thomson suggested that atoms contained far fewer electrons, a number roughly equal -
Rutherford: The Nuclear Model
Rutherford overturned Thomson’s model in 1911 with his famous gold-foil experiment, in which he demonstrated that the atom has a tiny, massive nucleus. Five years earlier Rutherford had noticed that alpha particles beamed through a hole onto a photographic plate would make a sharp-edged picture, while alpha particles beamed through a sheet of mica only 20 micrometres thick would make an impression with blurry edges. -
Bohr: The Bohr (Planetary) Model
In 1913 Niels Bohr came to work in the laboratory of Ernest Rutherford. Rutherford, who had a few years earlier, discovered the planetary model of the atom asked Bohr to work on it because there were some problems with the model: According to the physics of the time, Rutherford's planetary atom should have an extremely short lifetime. Bohr thought about the problem and knew of the emission spectrum of hydrogen. He quickly realized that the two problems were connected and after some thought came -
Bohr: The Bohr (Planetary) Model PART 2
Electrons assume only certain orbits around the nucleus. These orbits are stable and called "stationary" orbits.
Each orbit has an energy associated with it. For example the orbit closest to the nucleus has an energy E1, the next closest E2 and so on. -
Schrodinger: Quantum Mechanics Model
By 1926, the Austrian physicist Erwin Schrödinger was able to formulate an equation that helped to clear up the confusion that Heisenberg had caused by telling the world we can’t determine what the atom really looks like. Schrödinger accounted for the electron’s wave and particle properties. Schrödinger provided an equation that related the distance an electron could be found from the nucleus to the potential energy of the electron. It is by using Schrödinger’s equation that we are able to d
