Chemistry, URA-XEN
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.
Chemistry Encyclopedia Articles By Title
Uracil
Uracil, a colourless, crystalline organic compound of the pyrimidine family that occurs as a component of ribonucleic......
uranium
uranium (U), radioactive chemical element of the actinoid series of the periodic table, atomic number 92. It is......
uranium series
uranium series, set of unstable heavy nuclei constituting one of the four radioactive...
uranium-235
uranium-235 (U-235), radioactive isotope of the element uranium with a nucleus containing 92 protons and 143 neutrons.......
urea
urea, the diamide of carbonic acid. Its formula is H2NCONH2. Urea has important uses as a fertilizer and feed supplement,......
urea-formaldehyde resin
urea-formaldehyde resin, any of a class of synthetic resins obtained by chemical combination of urea (a solid crystal......
Urease
Urease, an enzyme that catalyzes the hydrolysis of urea, forming ammonia and carbon dioxide. Found in large quantities......
Urey, Harold C.
Harold C. Urey was an American scientist awarded the Nobel Prize for Chemistry in 1934 for his discovery of the......
uric acid
uric acid, a compound belonging to the purine group, and the chief form in which nitrogen, resulting from the breakdown......
Valine
Valine, an amino acid obtained by hydrolysis of proteins and first isolated by the German chemist Emil Fischer......
van der Waals forces
van der Waals forces, relatively weak electric forces that attract neutral molecules to one another in gases, in......
vanadic anhydride
vanadic anhydride, vanadium pentoxide, a compound of vanadium and oxygen widely used as an oxidation catalyst,......
vanadium
vanadium (V), chemical element, silvery white soft metal of Group 5 (Vb) of the periodic table. It is alloyed with......
Vane, Sir John Robert
Sir John Robert Vane was an English biochemist who, with Sune K. Bergström and Bengt Ingemar Samuelsson, won the......
varnish
varnish, liquid coating material containing a resin that dries to a hard transparent film. Most varnishes are a......
vasoactive intestinal polypeptide
vasoactive intestinal polypeptide (VIP), a 28-amino-acid polypeptide secreted by cells throughout the intestinal......
vasopressin
vasopressin, hormone that plays a key role in maintaining osmolality (the concentration of dissolved particles,......
Vauquelin, Nicolas-Louis
Nicolas-Louis Vauquelin was a French chemist who discovered the elements chromium (1797) and beryllium (1798).......
Venter, J. Craig
J. Craig Venter was an American geneticist, biochemist, and businessman who pioneered new techniques in genetics......
Vieille, Paul
Paul Vieille was a French scientist, known for his invention of smokeless powder. After studying with the chemist......
vinyl acetate
vinyl acetate, colourless, liquid organic compound, the polymer of which is polyvinyl acetate...
vinyl chloride
vinyl chloride, a colourless, flammable, toxic gas belonging to the family of organohalogen compounds and used......
vinyl compound
vinyl compound, any of various organic chemical compounds, including acrylic compounds and styrene and its derivatives,......
vinyl fluoride
vinyl fluoride (H2C=CHF), a colourless, flammable, nontoxic, chemically stable gas belonging to the family of organohalogen......
vinylidene chloride
vinylidene chloride, a colourless, dense, toxic, volatile, flammable liquid belonging to the family of organic......
Virtanen, Artturi Ilmari
Artturi Ilmari Virtanen was a Finnish biochemist whose investigations directed toward improving the production......
vitamin
vitamin, any of several organic substances that are necessary in small quantities for normal health and growth......
vitamin A
vitamin A, a fat-soluble alcohol, most abundant in fatty fish and especially in fish-liver oils. Vitamin A is also......
vitamin B complex
vitamin B complex, several vitamins that traditionally have been grouped together because of loose similarities......
vitamin B12
vitamin B12, a complex water-soluble organic compound that is essential to a number of microorganisms and animals,......
vitamin B6
vitamin B6, water-soluble organic compound that is an essential micronutrient for microorganisms and animals. It......
vitamin C
vitamin C, water-soluble, carbohydrate-like substance that is essential for human health. Chemically, it is a six-carbon......
vitamin D
vitamin D, any of a group of fat-soluble vitamins important in calcium metabolism in animals. It is formed by ultraviolet......
vitamin E
vitamin E, a fat-soluble compound found principally in certain plant oils and the leaves of green vegetables. Wheat-germ......
vitamin K
vitamin K, any of several fat-soluble naphthoquinone compounds. Vitamin K (from the Danish word koagulation) is......
vitriol
vitriol, any of certain hydrated sulfates or sulfuric acid. Most of the vitriols have important and varied industrial......
von Willebrand factor
von Willebrand factor (vWF, or VWF), glycoprotein that plays an important role in stopping the escape of blood......
Vrba, Rudolf
Rudolf Vrba was a Slovak Jewish biochemist, one of five Jewish prisoners to ever escape Auschwitz, the most lethal......
Wagner, Carl
Carl Wagner was a German physical chemist and metallurgist who helped advance the understanding of the chemistry......
Waksman, Selman Abraham
Selman Abraham Waksman was a Ukrainian-born American biochemist who was one of the world’s foremost authorities......
Wald, George
George Wald was an American biochemist who received (with Haldan K. Hartline of the United States and Ragnar Granit......
Walden, Paul
Paul Walden was a chemist who discovered the Walden inversion, a reversal of stereochemical configuration that......
Walker, John
John Walker is a British chemist who was corecipient, with Paul D. Boyer, of the Nobel Prize for Chemistry in 1997......
Wallach, Otto
Otto Wallach was a German chemist awarded the 1910 Nobel Prize for Chemistry for analyzing fragrant essential oils......
Warburg, Otto
Otto Warburg was a German biochemist awarded the Nobel Prize for Physiology or Medicine in 1931 for his research......
warfarin
warfarin, anticoagulant drug, marketed as Coumadin. Originally developed to treat thromboembolism (see thrombosis),......
Warshel, Arieh
Arieh Warshel is an American Israeli chemist who was awarded the 2013 Nobel Prize for Chemistry for developing......
washing soda
washing soda, sodium carbonate decahydrate, efflorescent crystals used for washing, especially textiles. It is......
water
water, a substance composed of the chemical elements hydrogen and oxygen and existing in gaseous, liquid, and solid......
Water Explained in 5 Questions
In the series Explained in 5 Questions, experts take on big topics and help you understand them better. list, water,......
Weizmann, Chaim
Chaim Weizmann was the first president of the new nation of Israel (1949–52), who was for decades the guiding spirit......
Welsbach, Carl Auer, Freiherr von
Carl Auer, Freiherr von Welsbach was an Austrian chemist and engineer who invented the gas mantle, thus allowing......
Werner, Alfred
Alfred Werner was a Swiss chemist and winner of the Nobel Prize for Chemistry in 1913 for his research into the......
What causes acid rain?
The main contributors to acid rain are sulfur dioxide (SO2) and nitrogen oxides (NOx; the combination of NO and......
What causes allergies?
Allergic reactions are caused by substances known as allergens. These substances can be found in a variety of sources......
What color is the hottest flame?
Want to know how hot a fire is burning? The color of its flames can help. When something burns, it is undergoing......
What Is Astatine Used For?
Astatine (At) has no established industrial, commercial, or household uses, because of its extreme scarcity and......
What is Hexavalent Chromium (or Chromium-6)?
Many people know hexavalent chromium as a silent antagonist in the biopic Erin Brockovich (2000), which starred......
What Is the Difference Between a Peptide and a Protein?
Proteins and peptides are fundamental components of cells that carry out important biological functions. Proteins......
What is the difference between cotton and polyester?
Cotton and polyester can both be made into fabrics, but they are otherwise very different. Cotton is a natural......
What Is the Difference Between DNA and RNA?
Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are complex molecular structures that control all hereditary......
What Is the Difference Between Iron and Steel?
Iron and steel differ in their composition and properties. Iron (Fe) is a chemical element and the most abundant......
What is the Statue of Liberty made of?
The Statue of Liberty is constructed of 31 tons of 0.1-inch- (2.4-mm-) thick copper sheets that were hammered into......
When Was the Periodic Table Invented?
The periodic table was invented by Russian chemist Dmitri Mendeleev in 1869. However, prior to Mendeleev, chemists......
Whitney, Willis Rodney
Willis Rodney Whitney was an American chemist and founder of the General Electric Company’s research laboratory,......
Whittingham, M. Stanley
M. Stanley Whittingham is a British-born American chemist who won the 2019 Nobel Prize in Chemistry for his work......
Why Are Flamingos Pink?
Flamingos are long-legged wading birds that are usually covered in bright pink feathers. With a name that derives......
Why Are Tomatoes Red?
Most tomatoes are red when they are ripe, because of the presence of lycopene, which is a phytochemical (a biologically......
Why do humans need water?
Water makes up more than half the body weight of adult humans. That value is 75 percent for babies. As an essential......
Why Do Onions Make You Cry?
You’re happily chopping onions for your dinner when BAM! Your eyes are stinging, and tears are running down your......
Why do radishes taste spicy?
Crisp and refreshing, a radish can pack a little kick. If your palate is sensitive, you may perceive its similarities......
Why Does Blood Taste Like Metal?
Blood is often described as having a metallic taste because it contains a large amount of iron, mainly within hemoglobin,......
Why does ice float on water?
Ice floats on water because it is less dense than its liquid form. In the liquid state, most water molecules are......
Why Does Water Freeze from the Top Down?
We drink water, we swim in it, we wash with it, and we cool things down with it. Because water is so common, many......
Why Is a Group of Molecules Called a Mole?
It’s one of the first things you learn in chemistry: Atoms and molecules are so small that even a few grams of......
Why Is Eating Protein Important?
There are three basic macronutrients that the body needs to survive: fats, carbohydrates, and proteins. Proteins......
Why is Mars called the Red Planet?
The distinct reddish color of Mars is primarily due to the presence of iron oxide (commonly called “rust”) in the......
Why is nitrogen essential to life?
Nitrogen is fundamental to life because it is needed to make DNA and RNA, which carry genetic information, and......
Why is the ocean blue?
When sunlight hits the ocean, the different wavelengths of light are either absorbed or scattered by water molecules......
Why Is the Ocean Salty?
“Water, water everywhere,/ Nor any drop to drink.” This famous line, spoken by the lost sailor in Samuel Taylor......
Why Is There Fresh and Salt Water on Earth?
Rain and other forms of precipitation fall on our planet as slightly acidic fresh water. As some of this water......
Wieland, Heinrich Otto
Heinrich Otto Wieland was a German chemist, winner of the 1927 Nobel Prize for Chemistry for his determination......
Wilkinson, Sir Geoffrey
Sir Geoffrey Wilkinson was a British chemist, joint recipient with Ernst Fischer of the Nobel Prize for Chemistry......
Williamson, Alexander William
Alexander William Williamson was an English chemist whose research on alcohols and ethers clarified organic molecular......
Willstätter, Richard
Richard Willstätter was a German chemist whose study of the structure of chlorophyll and other plant pigments won......
Windaus, Adolf
Adolf Windaus was a German organic chemist, winner of the Nobel Prize for Chemistry in 1928 for research on substances,......
Winkler, Clemens Alexander
Clemens Alexander Winkler was a German chemist who discovered the element germanium. After 12 years managing a......
Winter, Gregory P.
Gregory P. Winter is a British biochemist known for his development of the first humanized antibodies, his research......
Wislicenus, Johannes
Johannes Wislicenus was a German chemist whose pioneering work led to the recognition of the importance of the......
Wittig, Georg
Georg Wittig was a German chemist whose studies of organic phosphorus compounds won him a share (with Herbert C.......
Wollaston, William Hyde
William Hyde Wollaston was a British scientist who enhanced the techniques of powder metallurgy to become the first......
Woodward, Robert Burns
Robert Burns Woodward was an American chemist best known for his syntheses of complex organic substances, including......
Wrinch, Dorothy Maud
Dorothy Maud Wrinch was a British American mathematician and biochemist who contributed to the understanding of......
Wurtz, Charles-Adolphe
Charles-Adolphe Wurtz was a French chemist and educator noted for his research on organic nitrogen compounds, hydrocarbons,......
Wyckoff, Ralph Walter Graystone
Ralph Walter Graystone Wyckoff was an American research scientist, a pioneer in the application of X-ray methods......
Wöhler, Friedrich
Friedrich Wöhler was a German chemist who was one of the finest and most prolific of the 19th century. Wöhler,......
Wüthrich, Kurt
Kurt Wüthrich is a Swiss scientist who, with John B. Fenn and Tanaka Koichi, won the Nobel Prize for Chemistry......
xanthan gum
xanthan gum, water-soluble polysaccharide compound that is produced by the bacterium Xanthomonas campestris and......
xanthate
xanthate, any of a class of organic salts formed by treatment of an alcohol with carbon disulfide in the presence......
xenon
xenon (Xe), chemical element, a heavy and extremely rare gas of Group 18 (noble gases) of the periodic table. It......