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Greatest Discoveries of Chemistry - Реферат


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Greatest Discoveries of Chemistry

Pioneering discoveries that became turning points in the history of chemistry.

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 today.

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. Dalton's theory has undergone modifications through the centuries, but it has as much significance for the future of the science as Lavoisier's 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 Rutherford's theories, Danish physicist Niels Bohr (1885 – 1962) published his atomic structure model, postulating that electrons move in specific orbits around the nucleus; and that the chemical properties of an element are largely dependent of the number of electrons in the outer orbit. These discoveries led the way to a greater understanding of the physical interactions between atoms and molecules, a process called chemical bonding.

Periodic Table of the Elements (1860s – 1870s)

Russian chemist and inventor Dmitri Mendeleev (1834 – 1907) discovered that if he tabulize the sixty-three known elements in order of increasing atomic number, their chemical properties recur in periodic cycles. So he devised the periodic table of the elements that successfully predicted the existence of yet undiscovered elements. In fact, three were found in his lifetime: scandium, germanium and gallium. The design of the table has been refined and expanded as new elements are discovered, making it absolutely essential to the academic discipline of chemistry, and at the same time, supplying a very valuable tool in classifying, systematizing and studying different chemical behaviors.

Urea Synthesis (1820s)

Friedrich Whler (1800 – 1882), German physician and chemist, accidentally synthesized an organic substance, urea, from inorganic matter; and as a result, unintentionally overthrew vitalism, the belief that chemicals released by living organisms are essentially different from non-living things. His discovery started the new subfield of organic chemistry.

Chemical Structure (1850s)

Following years of researching carbon-carbon bonds, German organic chemist Friedrich Kekule (1829 – 1896) suggested that the chemical structure of benzene as a ring-shaped arrangement of six carbon atoms after having dreamt of a snake grasping its own tail. The structure explained the difficulty why carbon atoms have the ability to bond up to four atoms simultaneously, a property known as tetravalence. Kekule, with the breakthrough of his theory of chemical structure, led to a greater understanding of molecular structure and resulted in the explosive development of the field of organic chemistry.

Electrolysis (1800s)

Having discovered that electricity can alter chemicals, British inventor Humphry Davy (1778 – 1829) pioneered the use of electrolysis as a method for splitting up chemical compounds into their constituent parts by passing an electric current through them. With numerous batteries used in electrolysis, he discovered several new elements: potassium, sodium, strontium, boron, magnesium and barium.

Atoms Have Signatures of Light (1850s)

German physicist Gustav Kirchhoff (1824 – 1887) and chemist Robert Bunsen (1811 – 1899) worked together in a field called spectrum analysis and learned that every element either absorbs or releases light at discrete wavelengths, producing discrete spectral lines. Though Kirchhoff and Bunsen did not understand about the existence of energy on the atomic level, the existence of spectral lines was satisfactorily explained by the Bohr's atomic model, leading to the development of a completely new field called quantum mechanics.

Radioactivity (1890s – 1900s)

Marie (1867 – 1934) and Pierre Curie (1859 – 1906) were able to extract uranium from pitchblende, and noted that the pitchblende seem to be more active than what they had extracted. They deduced that the ore, aside from uranium, contain traces of an unknown substance or element that are radioactive. Their study led to the discovery of new elements, which they dubbed as polonium and radium.

Plastics (1860s, 1900s)

In 1869, American inventor John Wesley Hyatt (1837 – 1920) was able to develop a commercially viable way of producing celluloid plastic in his effort to find an ivory substitute for manufacturing billiard balls. Celluloid became the first synthetic plastic and was utilized as a replacement for more expensive materials as ivory, amber and tortoiseshell. By the first decade of the twentieth century, Belgian-born American chemist Leo Baekeland (1863 – 1944) invented the first hard moldable plastic called Bakelite, a synthetic substitute characterized by insulating and heat-resistant properties. Soon it permeated almost every branch of industry, and became a ubiquitous presence in nearly every object in society. However, the use of plastics has raised serious environmental concerns in the last few decades.

Fullerenes (1980s)

Chemists Robert Curl (1933 – ), Harold Kroto (1936 – ) and Richard Smalley (1943 – 2005) discovered a very stable although not necessarily unreactive form of carbon with cage-like molecular structure. Other carbon compounds of similar structure have also been discovered and are collectively known as buckminsterfullerenes or fullerenes. The structures are made up entirely of carbon molecules arranged in spherical, ellipsoidal, tubular or ring-shaped form. The term was named after Richard Buckminster Fuller (1895 – 1983), who was an architect best known for creating geodesic-domed structures in the mid-twentieth century, which are sometimes referred as buckyballs.


1. Greatest Discoveries in the Field of Chemistry. SCIENCERAY http://scienceray.com/chemistry/greatest-discoveries-in-the-field-of-chemistry/

2. Chemistry. From Wikipedia, the free encyclopedia. http://en.wikipedia.org/wiki/Chemistry