Please enable JavaScript.
Coggle requires JavaScript to display documents.
History of the atom (. (Atomic number = Amount of protons, Atomic mass is…
History of the atom
.
-
-
-
-
When a element is represented as a number over another number with the element symbol, the top number is the mass number and the bottom number is the atomic number.
Rutherford used Alpha particles in his experiment. An alpha particle is a very large particle that is slow and deadly
-
John Dalton (1766-1844)
Transformed Democritus's ideas on atoms into a scientific theory. Formulated Dalton's atomic theory.
Dalton's atomic theory-
1. All elements are composed of tiny indivisible particles called atoms.
2. Atoms of the same element are identical and are different than atoms of other elements.
3. Atoms of different elements can physically mix together in whole-number ratios to form compounds.
4. Chemical reactions occur when atoms are separated, joined, or rearranged, but atoms never change into atoms of other elements during a chemical reaction.
-
J.J. Thomson (1856-1940)
Discovered the electron
His experiments consisted of a model that involved passing an electric current through gasses at very low pressure. He sealed the gasses in glass tubes fitted at both ends with metal discs called electrodes. One electrode became positively charged while the other became negatively charged. The result was a glowing beam, or cathode ray, that traveled from cathode (the negatively charged electrode) to the anode (the positively charged electrode.) He then set up an experiment to determine the ratio of the charge of an electron to its mass
-
-
-