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Democritus
He had the first idea of the atomic universe. His model was a round sphere. He was the father of modern science. -
John Dalton
He created Dalton's law: "in a mixture of non-reacting gases, the total pressure exerted is equal to the sum of the partial pressures of the individual gases." He researched Daltonism, or color blindness. He also studied the atomic theory. His model is the Billiard model, similar to Democritus' model. -
Billiard ball model
John Dalton proposed a basic model of the atom that helped establish many scientific concepts and also created the foundation for more modern models. His model suggested that atoms are the smallest particle of an element, that atoms of different elements have different masses, and that they are solid, indestructible units - much like a billiard ball. -
JJ Thomson
He suggested that corpuscles, little bits of an atom, make up the atom. He experimented with electricity and glass tubes. He created the plum pudding model. -
Electron
JJ Thomson discovered it when he was investigating thermionic emissions. -
Cathode ray tube
The cathode ray tube or (CRT) is a vacuum tube containing one or more electron guns, and a fluorescent screen used to view images. -
Plum pudding model
The atom is composed of electrons surrounded by a positive charge. Thomson created it. -
Gold foil experiment
The Geiger–Marsden experiments (also called the Rutherford gold foil experiment) we're experiments that scientists used to discover that every atom contains a nucleus where its positive charge and most of its mass is concentrated. -
Niels Bohr
He developed the Bohr model of the atom, in which he proposed that energy levels of electrons are discrete and that the electrons revolve in stable orbits around the atomic nucleus but can jump from one energy level (or orbit) to another. -
Ernest Rutherford
He was the father of nuclear physics. He discovered the concept of radioactive half-life. He theorized that atoms have their charge concentrated in a small nucleus. He created the Rutherford model. -
Proton
Ernest Rutherford conducted an experiment in which he discovered that all atoms must have a concentrated positive center charge that contains most of the atom's mass. He suggested that the nucleus contained a particle with a positive charge called a proton. -
Nuclear model
It was created by Rutherford. It is like the plum pudding model, but it has a distinct nucleus. -
Solar system/Bohr model
It was created by Bohr. It depicts the positively charged nucleus surrounded by electrons traveling in circular orbits around it. -
Quantum Mechanical model
Bohr and Heisenberg put forth the theories it was based off of. The electrons still travel around the positively charged nucleus, but in clouds instead of definite circles. -
Schrödinger and Heisenberg
Schrödinger developed a model of a complete atom interacting as waves. Heisenberg developed the uncertainty principle. They theorized that no experiment can measure the position and momentum of a quantum particle simultaneously. -
Neutron
James Chadwick fired the neutrons at a block of paraffin wax, which has a high concentration of hydrogen and is therefore rich in protons. Some of the neutrons collided with protons in the wax and knocked them out. Chadwick could then detect these protons and measure their energy.
