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The Start
In 1803 John Dalton started the first atomic hypothisis -
Event 2
In 1811 Amedeo Avogadro suggested that similar volumes of gases at equal temperatures and pressure contain the same number of particles , which fixed a flaw in Dalton's theory. Avogadro's law established a distinct line between atoms and molecules and allowed for the precise estimation of the atomic masses of various elements. -
Event 3
Robert Brown, a botanist, made another important contribution to atomic theory in 1827 when he noted that dust particles floating in water appeared to move randomly and for no apparent reason. Albert Einstein proposed in 1905 that the mobility of water molecules was the cause of Brownian motion. The model backed up particle theory and atomic theory, and Jean Perrin validated it in 1908. -
Event 4
Atoms were thought to be the tiniest units of matter up until this moment. J.J. Thomson made the electron discovery in 1897. He thought it was possible to split atoms. He suggested a plum pudding model of the atom, in which electrons were lodged in a mass of positive charge to produce an electrically neutral atom, because the electron carried a negative charge. -
Event 5
One of Thomson's pupils, Ernest Rutherford, refuted the plum pudding model in 1909. Rutherford discovered that an atom's positive charge and the majority of its mass are located in its center, or nucleus. In his planetary concept, electrons revolved around a tiny, positively charged nucleus. -
Event 6
Rutherford was on the correct road, but his model was unable to account for the emission and absorption spectra of atoms, as well as the reason why the electrons didn't collide with the nucleus. The Bohr model, put forward by Niels Bohr in 1913, holds that electrons can only orbit the nucleus at set distances from it. In contrast to spiraling into the nucleus, electrons might, in accordance with his hypothesis, make quantum leaps between energy levels. -
Event 8
Louis de Broglie proposed a wavelike behavior of moving particles, which Erwin Schrödinger described using Schrödinger's equation (1926). This, in turn, led to Werner Heisenberg's uncertainty principle (1927), which states that it's not possible to simultaneously know both the position and momentum of an electron. -
Event 7
Although Bohr's model included the behavior of atoms with many electrons, it did not cover the spectral lines of hydrogen. The knowledge of atoms has been enhanced by numerous discoveries. Isotopes are varieties of an atom of one element with various numbers of neutrons, as defined by Frederick Soddy in 1913. In 1932, neutrons were identified. -
Diagram of an atom
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Summary Part 1
An atomic theory based on quantum mechanics postulates that atoms are made up of smaller particles. Despite having the potential to be anywhere in the atom, the electron is most frequently found in an atomic orbital or energy level. -
Summary part 2
Atomic theory of the present day describes orbitals that can be spherical, dumbbell-shaped, etc. as opposed to the circular orbits of Rutherford's model. Due to the particles' slow speed relative to light, relativistic effects are present for atoms with a large number of electrons. The protons, neutrons, and electrons are made up of smaller particles now that modern science has discovered them, but the atom is still the smallest piece of matter that cannot be broken down chemically.