-
500
Democritus
Idea/experiment
That there was a limit to how much matter could be subdivided and that there existed an ultimate, indivisible particle called an atom.
How this contributed to our understanding of the atom.
It tells us that if you split an atom, devastating effects could occur, through nuclear fusion. -
Isaac Newton
Idea/experiment
Suggested a, “mechanical universe,” with small solid masses in motion. -
John Dalton
Idea/experiment
Suggested an,” atomic theory,” with spherical solid atoms based upon measurable properties of mass.
How this contributed to our understanding of the atom.
Elements are made up of tiny particles called atoms. -
G.J. Stoney
idea/experiment
He estimated the number of molecules in a cubic millimeter of gas, at room temperature and pressure, from data that was given from the atomic theory of gases. -
J.J Thomson
idea/experiment
He proved many scientists wrong by proving that atoms were not indivisible particles of matter, and said they contained particles called electrons imbedded in a positive sphere and put forward a model of a solid atom.
How this contributed to our understanding of the atom.
That an atom contains protons, electrons and neutrons. -
Max Planck
idea/experiment
Suggested the idea of using discrete units of energy to explain “hot, glowing matter.”
How has this contributed to our understanding of the atom?
That matter can give out bursts of energy to create the glowing matter. -
Hantaro Nagaoka
idea/experiment
Though that Thomson’s model was inaccurate and suggested another model where a positively charged centre is surrounded by a number of revolving electrons.
How has this contributed to our understanding of the atom?
It gives me the idea of electron shells. -
Robert Millikan
idea/experiment
Discovered the mass and charge of the electron, and said that all other charges were due to the presence or absence of electrons.
How does this contribute to our understanding of the atom?
That electrons have a negative charge. -
Ernest Rutherford
idea/experiment
After experimenting with scattering of alpha particles by gold foil and noting that they went straight through and concluded by saying that an atom must be mostly be empty space with a small, solid, positively charged central nucleus.
how does this contribute to our understanding of the atom?
That atoms were mostly empty. -
H.G.J Moseley
idea/experiment
Found that the atoms of each element contained a unique positive charge in their nucleus.
how did this contribute to our understanding of the atom?
Atom’s “uniqueness,” came from the number of protons it contained. -
Niels Bohr
idea/experiment
Suggested that atoms could only have a certain amount of energy.
how does this contribute to our understanding of the atom?
That atoms can only emit certain amounts of energy. -
James Chadwick
idea/experiment
Discovered the nucleus. Because they had no charge, they are able to even penetrate the nuclei of even the heaviest elements.
how does this contribute to our understanding of the atom?
That neutrons are not repelled by electrons.
