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Joseph Proust
His father served as an apothecary in Angers. Joseph studied chemistry in his father’s shop and later came to Paris where he gained the appointment of apothecary in chief to the Salpetriere.He also taught chemistry with Pilâtre de Rozier, a famous aeronaut.Proust's best known work was derived from a controversy with chemist C.L. Berthollet. Berthollet did not believe that substances always combine in constant and definite proportions as Proust did. Proust proved Berthollet wrong in 1799. -
John Dalton
He was an English chemist, meteorologist and physicist, 1st Atomic Theory of Matter based on scientific evidence. He is considered the Father of Modern Atomic Theory, His efforts gave us our understanding of the atom bringing it from an abstract philosohical concept from Ancient Greece toa concrete reality. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness (sometimes referred to as Daltonism, in his honour). -
Antoine Lavoisier
the "father of modern chemistry", was a French nobleman prominent in the histories of chemistry and biology. He found and termed both oxygen (1778) and hydrogen (1783), helped construct the metric system, put together the first extensive list of elements, and helped to reform chemical nomenclature.He was also the first to establish that sulfur was an element (1777) rather than a compound. He discovered that, although matter may change its form or shape, its mass always remains the same. -
1782 Lavoisier Law of Conservation of Mass
The law of conservation of mass, also known as the principle of mass/matter conservation, states that the mass of a closed system (in the sense of a completely isolated system) will remain constant over time. This principle is equivalent to the conservation of energy, in the sense when energy or mass is enclosed in a system and none is allowed in or out, its quantity cannot otherwise change (hence, its quantity is "conserved"). -
1799 Proust Law of Definite Proportions
The law of definite proportions, sometimes called Proust's Law, states that a chemical compound always contains exactly the same proportion of elements by mass. An equivalent statement is the law of constant composition, which states that all samples of a given chemical compound have the same elemental composition. -
1803 Dalton's Atomic Theory
he worked on and developed his theory, Dalton postulated four axioms: elements are made up of atoms, all atoms in an element are identical, atoms of different elements can be identified by their atomic weight and that atoms of different elements can be combined by chemical reaction to form chemical compounds in fixed ratios.He also theorized that atoms could not be destroyed, created, or divided since they are the smallest particles. -
Dalton's Law of Multiple Proportion
If two elements form more than one compound between them, then the ratios of the masses of the second element which combine with a fixed mass of the first element will be ratios of small whole numbers.John Dalton specified that the law did not have to be followed in regards to just two of the same elements forming,The Law of Multiple Proportions, is one constant element within differing compounds sharing the same type of chemical bonding.
