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Greatest Discoveries of Chemistry ()
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Greatest Discoveries of Chemistry


Pioneering discoveries that became turning points in the history of



Oxygen (1770s)


British educator and philosopher Joseph Priestley (1733 1804)

discovered oxygen in experiments, isolated the gas, and described its

function in combustion and respiration. He also invented soda or

carbonated water by dissolving fixed air with water. Unaware of the

significance of his discoveries and because of his stubborn refusal to

abandon the phlogiston theory, he named the new gas dephlogisticated

air. However, it would be the French chemist Antoine Lavoisier (1743

1794) who gave the gas its present name, and was able to explain the

nature of the element, accurately describing its role in combustion that

totally discredit the phlogiston theory. In addition, Lavoisier

collaborated with others to develop a systematic chemical nomenclature

that facilitates dialogue among chemists and is still very much in use



Atomic Theory (1800s)


John Dalton (1766 1844), English chemist and physicist, proposed the

atomic theory, which states that: a.) all elements are made up of tiny

particles called atoms; b.) all atoms of an element are identical; c.)

the atoms of dissimilar elements can be distinguished from one another

by their corresponding relative weights; d.) atoms of an element can be

combined with atoms of another elements to form chemical compounds; and

e.) atoms cannot be created, broken down into smaller particles, nor

destroyed in a chemical process. He also presented a way of associating

invisible atoms with quantifiable amounts such as mass of a mineral or

volume of a gas. Daltons theory has undergone modifications through the

centuries, but it has as much significance for the future of the science

as Lavoisiers oxygen-based chemistry had been.


Molecules are Made Up of Atoms (1810s )


At a time when the words atom and molecule were used

interchangeably, Italian scientist Amedeo Avogadro (1776 1856)

clarified that atoms combine to form molecules; and proposed his

eponymous principle which asserts that Equal volumes of ideal gases, at

the same conditions of temperature and pressure, contain equal numbers

of particles or molecules.


The Electron (1890s)


Through a series of experiments using cathode ray tubes, J. J. Thomson

(1856 1940) discovered that cathode rays emitted negative charged

particles, a component that makes up atoms. He called these particles

corpuscles, now known as electrons. He proposed that plum pudding

model, in the belief that atoms consisted of an abundance of these

corpuscles teeming in an ocean of positive charged particles; but this

was subsequently proven to be erroneous when Ernest Rutherford (1871

1937) developed the orbital theory of the atom and discovered through

his famous gold foil experiment that atomic masses are largely

concentrated in the nucleus surrounded by electrons.


Electrons for Chemical Bonds (1910s )


On the foundation of Ernest Rutherfords theories, Danish physicist

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