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Democritus
The Democritus Atomic Theory revolves around the atoms that are present in the atmosphere like the atoms that are here that existence like a solid or liquid. The theory says that these atoms are all individually created and cannot be separated, no matter what. -
John Dalton
He was nicknamed the "Father of Atomic Theory" because he was the first one to come up with the modern atomic model. His model was claimed to be one of the fundamentals of physics and chemistry and was the first model to have claims backed up by scientific experiments.This model incorrectly classified atoms as invisible and indestructible particles. -
JJ Thomson
Thomson’s model did not have any protons but had electrons. Thomson thought that the deflection of the rays electrically charged plates and magnets. Thomson said that this model had negative charge electrons inside a sphere of positive charges so the charges were balanced. -
Albert Einstein
Proposed the quantum of light in which he states that light
behaves like a particle but also has a wave nature, giving it
a dual nature. Stated the equivalence of energy and mass
through the theory of special relativity. -
Ernest Rutherford
He discovered that the atoms contained more than just a nuclei. He stated that the atom contained protons and electrons and he described the atom as resembling the solar system. He found out that all known radioactive elements emit two kinds of radiation: positively and negatively charged. The problem about Rutherford's model was that he said the electrons orbit around the nuclei but it went all over the place. -
Niels Bohr
Bohr's model was the first to predict and explain the atomic spectrum of the hydrogen atom, which goes as the electron jumps from one orbit to another orbit of lower energy, giving off electromagnetic radiation of predictable frequencies. Later models of atomic structure abandoned the idea of circular orbits, and explained the stable orbits as standing waves. -
Hans geiger
In 1910, with Rutherford, they showed that 2 alpha-particles are put in the radioactive decay of uranium and in 1912, with J. M. Nuttal, they proved that this is caused by 2 uranium isotopes. The Geiger-Nuttall rule of 1911, states that the relationship is linear between the logarithm of the range of alpha-particles and the radioactive time constant, which is involved in the rate of decay of emitting nucleus. -
Erwin Schroedinger
Schrodinger used mathematical equations to describe the likelihood of finding an electron in a certain position. This atomic model is known as the quantum mechanical model of the atom.The quantum mechanical model does not define the exact location of an electron but it predicts where it wouldnt go. This model can be portrayed as a nucleus surrounded by an electron cloud. This model introduced the concept of sub-energy levels. -
Werner Heisenberg
The Electron Cloud Model was discovered in the 1930's and was founded by Werner Heisenberg. This electron does not describe the path of each electron in a fixed orbit but it can probably show where the electrons can be found. This model describes a cloud like thing where the electron is likely to be found. -
James Chadwick
James Chadwick proved the existence of neutrons in 1932. As uncharged particles in atoms, neutrons play a key part in nuclear fission, or the splitting of atoms. -
Otto Hahn
Found that when Uranium is bombarded by neutrons it
produces smaller nuclei roughly half the size of the original
Uranium nucleus. -
Lise Meitner
Lise worked with Hahn and she realized that Hahn was splitting the Uranium nucleus,
something never done before. Lise's invention (known as atom splitter) releases neutrons at different atoms in the Table of the Elements. -
Period: to
Atomic Model Timeline - Keturah Wittig-Souza
Keturah Wittig-Souza
Period 6
