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John Dalton
All matter is composed of atoms
Atoms cannot be made or destroyed
All atoms of the same element are identical
Different elements have different types of atoms
Chemical reactions occur when atoms are rearranged
Compounds are formed from atoms of the constituent elements.~John Dalton -
JJ Thompson
In 1897, J. J. Thomson announced his discovery of the electron and the fact that atoms must therefore have some structure. -
Ernest Ruthford
in 1911, Rutherford designed a new model of the atom in which all of the positive charge are inside a tiny, massive nucleus about ten thousand times smaller than the atom as a whole. That's equivalent in scale to a marble in the middle of a football stadium. The much lighter electrons, he assumed, lay well outside the nucleus. To the shock and amazement of everyone, the atoms of which planets, people, pianos, and everything else are made consisted almost entirely of empty space. -
Niels Bohr
The Bohr model consists of four principles:
1) Electrons assume only certain orbits around the nucleus. These orbits are stable and called "stationary" orbits.
2) Each orbit has an energy associated with it. For example the orbit closest to the nucleus has an energy E1, the next closest E2 and so on.
3) Light is emitted when an electron jumps from a higher orbit to a lower orbit and absorbed when it jumps from a lower to higher orbit.
4) The energy and frequency of light emitted or absorbed i -
Erwin Schrödinger
An Austrian physicist named Erwin Schrödinger derived a set of equations or wave functions in 1926 for electrons. According to Schrodinger, electrons confined in their orbits would set up standing waves and you could describe only the probability of where an electron could be. The distributions of these probabilities formed regions of space about the nucleus were called orbitals. Orbitals could be described as electron density clouds. The densest area of the cloud is where you have the greatest
