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Period: 100 to
atomic timeline
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406
Democritus
Democritus believed atoms can combine as they have different shapes - believed everything is either made up of space or atoms - thought that atoms determine properties, edges of atoms lead to the differences in taste and colour of substances - he does not have a scientific evidence, but attempted to explain the concept of an atom and how atoms form the physical world. -
Dalton
Proposed his modern theory of the atom. Matter is made up of atoms that are indivisible and indestructible - All atoms of an element are identical - Atoms of different elements have different weights and different chemical properties - Atoms of different elements combine in simple whole numbers to form compounds - Atoms cannot be created or destroyed. When a compound decomposes, the atoms are recovered unchanged. -
Plum pudding model
The plum pudding model of the atom by J. J. Thomson, who discovered the electron in 1897. In this model, the atom is composed of electrons surrounded by a soup of positive charge to balance the electrons' negative charges, like negatively charged "plums" surrounded by positively charged "pudding". -
Thomson
all models of the atom looked like a big solild ball until J.J. Thomson discovered the electron, which led him to create the "plum pudding" atomic model. In this model, he thought that the atom was mostly positive, and negative electrons wandered around the atom. The "plum pudding" model inspried other scientists. -
Rutherford
J.J. Thomson's model was incorrect, so he come up with a new model. He found the nucleus, and said that instead of the positive matter being the whole atom, it was just in the middle. He explained the atom was mostly empty space and that the electrons surrounded the positive nucleus. -
Bohr
Niels Bohr was a Danish scientist that was a student of Rutherford. He made a new model based off of Rutherford's model. He created energy levels in the atom, where only a certain amount of electrons could fit on one energy level of the atom. This model is still used to this day. -
atomic bomb
All existing nuclear weapons derive some of their explosive energy from nuclear fission reactions. Weapons whose explosive output is exclusively from fission reactions are commonly referred to as atomic bombs or atom bombs (abbreviated as A-bombs). This has long been noted as something of a misnomer, as their energy comes from the nucleus of the atom.
A major challenge in all nuclear weapon designs is to ensure that a significant fraction of the fuel is consumed before the weapon destroys itself -
Radiocarbon dating
The technique of radiocarbon dating was developed by Willard Libby and his colleagues at the University of Chicago in 1949 -
electron cloud
Electron clouds are created when accelerated charged particles disturb stray electrons already floating in the tube, and bounce or slingshot the electrons into the wall. These stray electrons can be photo-electrons from synchrotron radiation or electrons from ionized gas molecules.
