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Dalton Model
John Dalton imagined an atom to be shaped like a sphere. He published a book titled "New System of Chemical Philosophy" explaining that wach element is made of small atoms.
Dalton's Atomic Theory:
1. Atoms are invivible and indestructable
2. All atoms of a given element are identical in mass and proprerties
3. Compounds are formed by a combination of two or more elements
4. A chemical reaction is a rearrangement of atoms -
Thomson Model
J.J. Thomson proposed a model that suggests that an atom is a positively-charged sphere with electrons in the sphere. He compared this model to a muffin with berries in it. He discovered smaller parts in the atoms, which are now called electrons but he origanlly called them corpuscles. He used a CRT or cathode ray scope to find the electrons. He then creates the "plum pudding model" stating that elections are in a fixed position in the positively charged body of the atom. -
Nagaoka Model
Hantaro Nagaoka created the model that electrons orbit a positvely charged center in rings. He developed a planetary model based on Saturn's rings. The model made two predictions, a very massive nucleus and electrons revolving around the nucleus, bound by electrostatic forces. These predictions ended up being correct. -
Rutherford Model
Rutherford looked at Thomson's model where protons and electrons are scattered throughout the atom and thought that if it was possible, the mass of the atom would spread throughout the atom. He did an experiment disproving Thomson and discovering that the nucleus is mosst of the mass of an atom. He then decided that the electrons orbit the nucleus in rings. -
Bohr Model
The Bohr Model, created by Niels Bohr, suggested that how electrons revolve around the nucleus is similar to how the planets revolove around the sun. The difference is that the electrons arent confined to a predetermined plane. The electric force that keeps the electrons near the nucleus, coulumb, is stronger than gravity. -
Period: to
Modern Model
Atomic Timeline
The atom is now known as having a nucleus with neutrons and protons and electrons revolving around the nucleus. -
Chadwick Model
James Chadwick was responsible for the discovery of the neutron. A neutron is located in the nucleus and has the same mass as a proton. Scientists now refer to the nucleus as having protons and neutons.
