الرئيسية » Simplified Chemistry (صفحه 10)

Simplified Chemistry

Ascorbic Acid

Ascorbic acid A white, crystalline compound, also known as vitamin C. It is highly soluble in water, which is a stronger reducing agent than the hexose sugars, which it resembles chemically. Vitamin C deficiency in humans has been known for centuries as scurvy.The compound has the structural formula shown below. …

أكمل القراءة »

Amid

Amide A derivative of a carboxylic acid with general formula RCONH2, where R is hydrogen or an alkyl or aryl radical. Amides are divided into subclasses, depending on the number of substituents on nitrogen. The simple, or primary, amides are considered to be derivatives formed by replacement of the carboxylic …

أكمل القراءة »

Americium

A chemical element, symbol Am, atomic number 95. The isotope 241 Am is an alpha emitter with a half-life of 433 years. Other isotopes of americium range in mass from 232 to 247, but only the isotopes of mass 241 and 243 are important. The isotope 241Am is routinely separated …

أكمل القراءة »

Alum

A colorless to white crystalline substance which occurs naturally as the mineral kalunite and is a constituent of the mineral alunite. Alum is produced as aluminum sulfate by treating bauxite with sulfuric acid to yield alum cake or by treating the bauxite with caustic soda to yield papermaker salum. Other …

أكمل القراءة »

Alkyne

Alkyne One of a group of organic compounds containing a carbon-to-carbon triple-bond linkage (-C≡C-). They are termed acetylenes or alkynes. While exhibit­ing many of the characteristics of alkenes as regards unsaturation, the acetylenes have many unique properties. Since the bonding in alkyne molecules is linear. R-C≡C-R, cis-trans isomerism is not …

أكمل القراءة »

Alkylation-petroleum

Alkylation (petroleum) In the petroleum industry, a chemical process in which an alkene (ethylene, propylene, and so forth) and a hydrocarbon, usually 2-methylpropane, are combined to produce a higher-molecular-weight and higher­carbon-number product. The product has a higher octane rating and is used to improve the quality of gasoline-range fuels. The …

أكمل القراءة »

alkaloid

Alkaloid A cyclic organic compound that contains nitrogen in a negative oxidation state and is of limited distribution among living organisms. Over 10,000 alkaloids of many different structural types are known; and no other class of natural products possesses such an enormous variety of structures. Therefore, alkaloids are difficult to …

أكمل القراءة »

Alkaline-earth metals

Usually calcium, strontium, and barium, the heav­iest members of group 2 of the periodic table (excepting radium). Other members of the group are beryllium, magnesium, and radium, sometimes included among the alkaline-earth metals. Beryllium resembles aluminum more than any other element, and magnesium behaves more like zinc and cadmium. The …

أكمل القراءة »

Alkali

Any compound having highly basic properties, strong acrid taste, and ability to neutralize acids. Aqueous solutions of alkalies are high in hydroxyl ions, have a pH above 7, and turn litmus paper from red to blue. Caustic alkalies include sodium hydroxide (caustic soda), the sixth-largest-volume chemical produced in the United States, …

أكمل القراءة »

Alicyclic hydrocarbon

An organic compound that contains one or more closed rings of carbon atoms. The term alicyclic specifically excludes carbocyclic com­pounds with an array of n-electrons characteristic of aromatic rings. Compounds with one to five alicyclic rings of great variety and complexity are found in many natural products such as steroids.and …

أكمل القراءة »