Páginas: 7 (1523 palabras) Publicado: 27 de febrero de 2013
Chemistry, a branch of physical science, is the study of the composition, properties and behavior of matter.[1][2] Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds. Chemistry is also concerned with the interactions between atoms (or groups of atoms) and various forms of energy (e.g. photochemical reactions, changesin phases of matter, separation of mixtures, properties of polymers, etc.).
Chemistry is sometimes called "the central science" because it bridges other natural sciences like physics, geology and biology with each other.[3][4] Chemistry is a branch of physical science but distinct from physics.[5]
The etymology of the word chemistry has been much disputed.[6] The genesis of chemistry can betraced to certain practices, known as alchemy, which had been practiced for several millennia in various parts of the world, particularly the Middle East.[7]
Contents [hide]
1 Etymology
1.1 Definition
2 History
3 Principles of modern chemistry
3.1 Matter
3.1.1 Atom
3.1.2 Element
3.1.3 Compound
3.1.4 Substance
3.1.5 Molecule
3.1.6 Mole and amount of substance
3.2 Properties
3.2.1 Ionsand salts
3.2.2 Acidity and basicity
3.2.3 Phase
3.2.4 Bonding
3.3 Reaction
3.3.1 Redox
3.3.2 Equilibrium
3.3.3 Energy
3.4 Chemical laws
4 Practice
4.1 Subdisciplines
4.2 Chemical industry
4.3 Professional societies
5 See also
6 References
7 Further reading

Main article: Chemistry (etymology)
The word chemistry comes from the word alchemy, an earlier set of practicesthat encompassed elements of chemistry, metallurgy, philosophy, astrology, astronomy, mysticism and medicine; it is commonly thought of as the quest to turn lead or another common starting material into gold.[8] Alchemy, which was practiced around 330, is the study of the composition of waters, movement, growth, embodying, disembodying, drawing the spirits from bodies and bonding the spirits withinbodies (Zosimos).[9] An alchemist was called a 'chemist' in popular speech, and later the suffix "-ry" was added to this to describe the art of the chemist as "chemistry".
The word alchemy in turn is derived from the Arabic word al-kīmīā (الكيمياء). The Arabic term is borrowed from the Greek χημία or χημεία.[10][11] This may have Egyptian origins. Many believe that al-kīmīā is derived from χημία,which is in turn derived from the word Chemi or Kimi, which is the ancient name of Egypt in Egyptian.[10] Alternately, al-kīmīā may be derived from χημεία, meaning "cast together".[12]
In retrospect, the definition of chemistry has changed over time, as new discoveries and theories add to the functionality of the science. The term "chymistry", in the view of noted scientist RobertBoyle in 1661, meant the subject of the material principles of mixed bodies.[13] In 1663, "chymistry" meant a scientific art, by which one learns to dissolve bodies, and draw from them the different substances on their composition, and how to unite them again, and exalt them to a higher perfection - this definition was used by chemist Christopher Glaser.[14]
The 1730 definition of the word"chemistry", as used by Georg Ernst Stahl, meant the art of resolving mixed, compound, or aggregate bodies into their principles; and of composing such bodies from those principles.[15] In 1837, Jean-Baptiste Dumas considered the word "chemistry" to refer to the science concerned with the laws and effects of molecular forces.[16] This definition further evolved until, in 1947, it came to mean the scienceof substances: their structure, their properties, and the reactions that change them into other substances - a characterization accepted by Linus Pauling.[17] More recently, in 1998, the definition of "chemistry" was broadened to mean the study of matter and the changes it undergoes, as phrased by Professor Raymond Chang.[18]

Main article: History of chemistry
See also: Alchemy,...
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