Chemistry, GUY-HYD

How do you use raw plant materials to manufacture a best-selling perfume? How do you engineer household products that are compliant with environmentally-oriented guidelines? The answers to these questions require an understanding of the laws of chemistry, the science that deals with the properties, composition, and structure of elements and compounds, as well as the transformations that such substances undergo and the energy that is released or absorbed during those processes. Chemistry is also concerned with the utilization of natural substances and the creation of artificial ones. Over time, more than 8,000,000 different chemical substances, both natural and artificial, have been characterized and produced. Chemistry's vast scope comprises organic, inorganic, physical, analytical, and industrial chemistry, along with biochemistry, environmental chemistry, medicinal chemistry, and much more. Through the dedicated efforts of people such as Robert Boyle, Dmitri Mendeleev, John Dalton, Marie Curie, and Rosalind Franklin, the field of chemistry has led to exciting innovations as well as crucial advances in our understanding of how the world functions, starting with the miniscule and unassuming atom.
Back To Chemistry Page

Chemistry Encyclopedia Articles By Title

Guyton de Morveau, Louis Bernard
Louis Bernard Guyton de Morveau was a French chemist who played a major part in the reform of chemical nomenclature.......
Haber, Fritz
Fritz Haber was a German physical chemist and winner of the 1918 Nobel Prize for Chemistry for his successful work......
hafnium
hafnium (Hf), chemical element (atomic number 72), metal of Group 4 (IVb) of the periodic table. It is a ductile......
Hahn, Otto
Otto Hahn was a German chemist who, with the radiochemist Fritz Strassmann, is credited with the discovery of nuclear......
Hall, Charles Martin
Charles Martin Hall was an American chemist who discovered the electrolytic method of producing aluminum, thus......
halocarbon
halocarbon, any chemical compound of the element carbon and one or more of the halogens (bromine, chlorine, fluorine,......
halogen
halogen, any of the six nonmetallic elements that constitute Group 17 (Group VIIa) of the periodic table. The halogen......
halon
halon, chemical compound formerly used in firefighting. A halon may be any of a group of organohalogen compounds......
Hantzsch, Arthur Rudolf
Arthur Rudolf Hantzsch was a German chemist who won fame at the age of 25 for devising the synthesis of substituted......
haptoglobin
haptoglobin, a colourless protein of the α-globulin fraction of human serum (liquid portion of blood plasma after......
hard water
hard water, water that contains salts of calcium and magnesium principally as bicarbonates, chlorides, and sulfates.......
Harden, Sir Arthur
Sir Arthur Harden was an English biochemist and corecipient, with Hans von Euler-Chelpin, of the 1929 Nobel Prize......
Harkins, William Draper
William Draper Harkins was an American chemist whose investigations of nuclear chemistry, particularly the structure......
Harmine
Harmine, hallucinogenic alkaloid found in the seed coats of a plant (Peganum harmala) of the Mediterranean region......
Harries, Carl Dietrich
Carl Dietrich Harries was a German chemist and industrialist who developed the ozonolysis process (Harries reaction)......
Harrison, Anna Jane
Anna Jane Harrison was an American chemist and educator who in 1978 became the first woman president of the American......
Hartwig, John F.
John F. Hartwig is an American chemist known for his work in organic synthesis. When Hartwig entered college, he......
Hassel, Odd
Odd Hassel was a Norwegian physical chemist and corecipient, with Derek H.R. Barton of Great Britain, of the 1969......
hassium
hassium (Hs), an artificially produced element belonging to the transuranium group, atomic number 108. It was synthesized......
Hatchett, Charles
Charles Hatchett was an English manufacturer, chemist, and discoverer in 1801 of niobium, which he called columbium.......
Hauptman, Herbert A.
Herbert A. Hauptman was an American mathematician and crystallographer who, along with Jerome Karle, received the......
Haworth, Sir Norman
Sir Norman Haworth was a British chemist, who, along with the Swiss chemist Paul Karrer, won the 1937 Nobel Prize......
Haynes, Elwood
Elwood Haynes was an American automobile pioneer who built one of the first automobiles. He successfully tested......
heat of formation
heat of formation, the amount of heat absorbed or evolved when one mole of a compound is formed from its constituent......
heavy water
heavy water (D2O), water composed of two atoms of deuterium, the hydrogen isotope with a mass double that of ordinary......
Heck, Richard F.
Richard F. Heck was an American chemist who was awarded the 2010 Nobel Prize for Chemistry for his work in using......
Heeger, Alan J.
Alan J. Heeger is an American chemist who, with Alan G. MacDiarmid and Shirakawa Hideki, won the Nobel Prize for......
Hegemann, Peter
Peter Hegemann is a German biochemist and biophysicist whose work contributed to the development of optogenetics—a......
helium
helium (He), chemical element, inert gas of Group 18 (noble gases) of the periodic table. The second lightest element......
Hell, Stefan
Stefan Hell is a Romanian-born German chemist who won the 2014 Nobel Prize for Chemistry for using fluorescent......
Helmont, Jan Baptista van
Jan Baptista van Helmont was a Flemish physician, philosopher, mystic, and chemist who recognized the existence......
hemagglutinin
hemagglutinin, any of a group of naturally occurring glycoproteins that cause red blood cells (erythrocytes) to......
Hemicellulose
Hemicellulose, any of a group of complex carbohydrates that, with other carbohydrates (e.g., pectins), surround......
Hemochromogen
Hemochromogen, compound of the iron-containing pigment heme with a protein or other substance. The hemochromogens......
hemoglobin
hemoglobin, iron-containing protein in the blood of many animals—in the red blood cells (erythrocytes) of vertebrates—that......
Henderson, Lawrence Joseph
Lawrence Joseph Henderson was a U.S. biochemist, who discovered the chemical means by which acid–base equilibria......
Henderson, Richard
Richard Henderson is a Scottish biophysicist and molecular biologist who was the first to successfully produce......
Henry, William
William Henry was an English physician and chemist who in 1803 proposed what is now called Henry’s law, which states......
heparin
heparin, anticoagulant drug that is used to prevent blood clots from forming during and after surgery and to treat......
heptachlor
heptachlor, largely banned insecticide closely related to chlordane. It is a white crystalline solid with a melting......
Herschbach, Dudley R.
Dudley R. Herschbach is an American chemist and educator who, with Yuan T. Lee and John C. Polanyi, was awarded......
Herschel, Sir John, 1st Baronet
Sir John Herschel, 1st Baronet was an English astronomer and successor to his father, Sir William Herschel, in......
Hershko, Avram
Avram Hershko is a Hungarian-born Israeli biochemist who shared the 2004 Nobel Prize for Chemistry with Aaron J.......
Herzberg, Gerhard
Gerhard Herzberg was a Canadian physicist and winner of the 1971 Nobel Prize for Chemistry for his work in determining......
Hess, Germain Henri
Germain Henri Hess was a chemist whose studies of heat in chemical reactions formed the foundation of thermochemistry.......
Hess’s law
Hess’s law, rule first enunciated by Germain Henri Hess, a Swiss-born Russian chemist, in 1840, stating that the......
heterogeneous reaction
heterogeneous reaction, any of a class of chemical reactions in which the reactants are components of two or more......
Hevesy, Georg Charles von
Georg Charles von Hevesy was a chemist and recipient of the 1943 Nobel Prize for Chemistry. His development of......
hexachloroplatinic acid
hexachloroplatinic acid (H2PtCl6∙6H2O), complex compound formed by dissolving platinum metal in aqua regia (a mixture......
HeyrovskĂœ, Jaroslav
Jaroslav HeyrovskĂœ was a Czech chemist who received the Nobel Prize for Chemistry in 1959 for his discovery and......
high-density polyethylene
high-density polyethylene (HDPE), linear version of polyethylene, a light versatile synthetic resin made from the......
Hildebrand, Joel H.
Joel H. Hildebrand was a U.S. educator and chemist whose monograph Solubility (1924; later editions, Solubility......
Hinshelwood, Sir Cyril Norman
Sir Cyril Norman Hinshelwood was a British chemist who worked on reaction rates and reaction mechanisms, particularly......
Hirschmann, Ralph F.
Ralph F. Hirschmann was an American chemist who is best known for his development of techniques for the chemical......
Histamine
Histamine, biologically active substance found in a great variety of living organisms. It is distributed widely,......
Histidine
Histidine, an amino acid obtainable by hydrolysis of many proteins. A particularly rich source, hemoglobin (the......
Histone
Histone, type of protein that plays a critical role in the structural organization and regulation of DNA within......
Hjelm, Peter Jacob
Peter Jacob Hjelm was a Swedish chemist who isolated the element molybdenum in 1781. Hjelm was educated at Uppsala......
Hodgkin, Dorothy
Dorothy Hodgkin was an English chemist whose determination of the structure of penicillin and vitamin B12 brought......
Hoff, Jacobus Henricus van ’t
Jacobus Henricus van ’t Hoff was a Dutch physical chemist and the first winner of the Nobel Prize for Chemistry......
Hoffmann, Roald
Roald Hoffmann is a Polish-born American chemist, who was a corecipient, with Fukui Kenichi of Japan, of the Nobel......
Hofmann, Albert
Albert Hofmann was a Swiss chemist who discovered the psychedelic drug LSD (lysergic acid diethylamide), which......
Hofmann, August Wilhelm von
August Wilhelm von Hofmann was a German chemist whose research on aniline, with that of Sir William Henry Perkin,......
Holley, Robert William
Robert William Holley was an American biochemist who shared the Nobel Prize in Physiology or Medicine in 1968 with......
Holliday junction
Holliday junction, cross-shaped structure that forms during the process of genetic recombination, when two double-stranded......
holmium
holmium (Ho), chemical element, a rare-earth metal of the lanthanide series of the periodic table. Holmium is a......
homogeneous reaction
homogeneous reaction, any of a class of chemical reactions that occur in a single phase (gaseous, liquid, or solid),......
homologous series
homologous series, any of numerous groups of chemical compounds in each of which the difference between successive......
Hopkins, Sir Frederick Gowland
Sir Frederick Gowland Hopkins was a British biochemist, who received (with Christiaan Eijkman) the 1929 Nobel Prize......
Hoppe-Seyler, Ernst Felix
Ernst Felix Hoppe-Seyler was a German physician, known for his work toward establishing physiological chemistry......
How do clouds form?
Cloud formation, a key part of the water cycle, begins as moist air ascends into the atmosphere. This occurs because,......
How do fireflies light up?
Fireflies light up summer nights using a chemical process known as bioluminescence, the key chemical players of......
How Do You Balance a Chemical Equation?
Balancing chemical equations is a useful skill in chemistry. The basis of chemical reactions is the idea that atoms......
How does dry cleaning work?
Dry cleaning works by using chemical solvents to clean textiles instead of water. In essence, dry cleaning still......
How does metal rust?
Rust is the result of a chemical reaction between metal, typically iron, and oxygen in the presence of moisture.......
How is gold formed?
Gold is formed through cosmic and geological processes that involve the concentration and deposition of the metal......
How Much Water Should a Person Drink in a Day?
The popular recommendation to drink 8 cups of water every day isn’t as definitive as it may seem. The amount of......
How Radioactive Isotopes are Used in Medicine
Radioactive isotopes, or radioisotopes, are species of chemical elements that are produced through the natural......
How Rare Are Rare-Earth Elements?
Not as rare as plutonium, but rarer than carbon. Come on. Don’t be cute. You’re Encyclopédia Britannica. You have......
Huber, Robert
Robert Huber is a German biochemist who, along with Johann Deisenhofer and Hartmut Michel, received the Nobel Prize......
humic acid
humic acid, one of two classes of natural acidic organic polymer that can be extracted from humus found in soil,......
Hund, Friedrich
Friedrich Hund was a German physicist known for his work on the electronic structure of atoms and molecules. He......
Hutton, James
James Hutton was a Scottish geologist, chemist, naturalist, and originator of one of the fundamental principles......
Hyaluronic acid
Hyaluronic acid, naturally occurring polysaccharide found in the extracellular matrix of vertebrate tissues, particularly......
Hyaluronidase
Hyaluronidase, any of a group of enzymes that catalyze the hydrolysis (chemical decomposition involving the elements......
hydrate
hydrate, any compound containing water in the form of H2O molecules, usually, but not always, with a definite content......
hydrazine
hydrazine, (N2H4), one of a series of compounds called hydronitrogens and a powerful reducing agent. It is used......
hydride
hydride, any of a class of chemical compounds in which hydrogen is combined with another element. Three basic types......
hydrochloric acid
hydrochloric acid, corrosive colourless acid that is prepared by dissolving gaseous hydrogen chloride in...
hydrofluorocarbon
hydrofluorocarbon (HFC), any of several organic compounds composed of hydrogen, fluorine, and carbon. HFCs are......
hydrogen
hydrogen (H), a colourless, odourless, tasteless, flammable gaseous substance that is the simplest member of the......
hydrogen bonding
hydrogen bonding, interaction involving a hydrogen atom located between a pair of other atoms having a high affinity......
hydrogen chloride
hydrogen chloride (HCl), a compound of the elements hydrogen and chlorine, a gas at room temperature and pressure.......
hydrogen cyanide
hydrogen cyanide, a highly volatile, colourless, and extremely poisonous liquid (boiling point 26° C [79° F], freezing......
hydrogen ion
hydrogen ion, strictly, the nucleus of a hydrogen atom separated from its accompanying electron. The hydrogen nucleus......
hydrogen peroxide
hydrogen peroxide, (H2O2), a colourless liquid usually produced as aqueous solutions of various strengths, used......
hydrogen sulfide
hydrogen sulfide, colourless, extremely poisonous, gaseous compound formed by sulfur with hydrogen (see...

Chemistry Encyclopedia Articles By Title