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Alchymist Atomic model
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Develop the theory—that all metals are composed of mercury and sulfur and that it is possible to change base metals into gold.
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Democritus greatest contribution to modern science was arguably the atomic theory he elucidated.
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Democritus called these infinitesimally small pieces of matter atomos, meaning "indivisible." He suggested that atomos were eternal and could not be destroyed.
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Democritus' Atom
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Democritus’s model stated that matter consists of invisible particles called atoms and a void (empty space). He stated that atoms are indestructible and unchangeable.
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Dalton's Model of an Atom
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Dalton's atomic theory proposed that all matter was composed of atoms, indivisible and indestructible building blocks. While all atoms of an element were identical, different elements had atoms of differing size and mass.
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John Dalton's theory was to show that he could tell an atom just by its weight. The modern atomic theory shows how atoms are more complicated than hydrogen.
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An atom can be further subdivided into protons, neutrons and electrons. However an atom is the smallest particle that takes part in chemical reactions. According to Dalton, the atoms of same element are similar in all respects. These atoms are known as isobars.
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Plump pudding model
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In this model the atom was also sometimes described to have a “cloud” of positive charge.
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The atom contains a small, massive, positively charged nucleus. He also agreed with Nagaoka that the electrons move in circular orbits outside the nucleus.
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Thomson realized that the accepted model of an atom did not account for negatively or positively charged particles.
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Nuclear model
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Rutherford's model shows that an atom is mostly empty space, with electrons orbiting a fixed, positively charged nucleus in set, predictable paths.
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With his well-known gold foil experiment in which he demonstrated that the atom has a tiny and heavy nucleus.
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The main problem with Rutherford's model was that he couldn't explain why negatively charged electrons remain in orbit when they should instantly fall into the positively charged nucleus.
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Rutherford-Bohr Model
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Niels Bohr proposed a theory for the hydrogen atom based on quantum theory that energy is transferred only in certain well defined quantities. Electrons should move around the nucleus but only in prescribed orbits. When jumping from one orbit to another with lower energy, a light quantum is emitted.
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Bohr's model is that it works very well for atoms with only one electron, like H or He+, but not at all for multi-electron atoms.
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Quantum mechanical model, proposed the model in which
electrons are treated as waves. -
A powerful model of the atom was developed by Erwin Schrödinger in 1926. ... The Schrödinger model assumes that the electron is a wave and tries to describe the regions in space, or orbitals, where electrons are most likely to be found.
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Schrödinger 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.
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It assumed that the electron is a wave and tries to describe the regions in space, or orbitals, where electrons are most likely to be found.
