Somewhere between the sizes of an atom and a grain of sand lies the realm of small particles called colloids. As will become evident, they are everywhere.
Whereas classical synthetic chemistry involves the stepwise synthesis and purification of a single compound at a time, combinatorial chemistry makes it possible to synthesize thousands of different molecules in a relatively short amount of time, usually without the intermediate separation of compounds involved in the synthetic pathway, and with a high degree of automation. Such procedures result in the production of new compounds faster and in greater numbers than is possible with standard synthetic methods.
In 1929, shortly after the emergence of quantum mechanics, Paul Dirac made his famous statement that in principle the physical laws necessary to understand all of chemistry were at that point known—the only difficulty was that their application to chemical systems generally led to equations that were too difficult to solve. Consequently, at that time quantum principles could be rigorously applied only to simple atoms and molecules, such as H, He, H2+, and H2.
A concentration gradient occurs where the concentration of something changes over a certain distance. For example, a few drops of food dye in a glass of water diffuse along the concentration gradient, from where the dye exists in its highest concentration (for instance, the brightest blue or red) to where it occurs in its lowest concentration (the water is still clear).
Transition metals readily react with halogens to form binary compounds of various colors, for example: green-black ferric chloride (FeCl3), deep blue cobalt chloride (CoCl2), and golden yellow nickel bromide (NiBr2). These compounds dissolve in water to give brightly colored solutions—but of changed colors: yellow solutions (containing Fe3+ ions), red solutions (Co2+ ions), and green solutions (Ni2+ ions).
Copper was first used by humans more than 10,000 years ago. A copper pendant discovered in what is now northern Iraq has been dated to about 8700 B.C.E.
Corrosion is the deterioration a material undergoes as a result of its interaction with its surroundings. Although this definition is applicable to any type of material, it is usually reserved for metallic alloys.
Cortisone is a steroid produced in the adrenal glands of the human body. The isolation of cortisone from the mixture of molecules produced in these glands was carried out by American biochemist Edward Kendall and coworkers.
The global market for skincare and color cosmetics exceeded 53 billion dollars in 2002. The number of new products brought to market continues to expand exponentially.
Cryogenics is the science that addresses the production and effects of very low temperatures. The word originates from the Greek words kryos meaning "frost" and genic meaning "to produce." Under such a definition, it could be used to include all temperatures below the freezing point of water (0°C).
A computed axial tomograph is an axial (cross sectional) view computed from a large set of values, each corresponding to the attenuation of an x-ray beam passed transversely (i.e. in the plane of the desired image) through the subject.
The element curium was discovered in 1944 by Glenn T. Seaborg, Ralph A.
Protein molecules carry out many important tasks in living systems. Most important, the majority of proteins are quite specific about which task they perform.
Deoxyribonucleic acid (DNA) is the genetic material of most living organisms. One of its main functions is to produce ribonucleic acid (RNA), which then makes proteins.
Soap and cleanliness are inseparable, and cleansing, be it personal hygiene or laundering, is part of human history. Stringent guidelines with regard to the cleanliness of holy sites are a part of all the major religions, and the sanctification of the state of cleanliness as well as its signification of purity of body and soul are recurrent themes in their liturgies.
X-ray technology provides physicians and technicians with a noninvasive method for seeing inside objects. In the case of a patient's body, this may allow diagnosis of disease or injury without surgery.
Sucrose, or table sugar, is the most common disaccharide. Although the term "sugar" is commonly used to refer to sucrose, sucrose is only one of a large group of sugars.
Carl and Gerty Cori were a husband-and-wife team who worked closely together on research into carbohydrate metabolism.
Frederick Cottrell invented the "electrostatic precipitator," which removes pollutants from smoke. Cottrell was born on January 10, 1877, in Oakland, California, the son of Henry and Cynthia Cottrell.
Charles-Augustin de Coulomb was born to affluent parents in Angoulême, France. His father's family was prominent in the legal profession and involved in the administration of the Languedoc region of France.
Physicist-chemist Marie Sklodowska Curie, sometimes referred to as the "mother of atomic physics," is perhaps the best-known woman scientist of all time—a legend of twentieth-century science. Cowinner of the Nobel Prize in physics in 1903, she was the first person to be awarded a second Nobel Prize, this time in chemistry, in 1911.
The fundamental idea of modern chemistry is that matter is made up of atoms of various sorts, which can be combined and rearranged to produce different, and often novel, materials. The person responsible for "this master-concept of our age" (Greenaway, p.
Sir Humphry Davy, the son of woodcarver, was born on December 17, 1778, in Penzance, Cornwall, then a highly industrialized area in the far west of England. In 1798 he moved to Bristol to work at the Pneumatic Institution under Thomas Beddoes, a physician who used gases for medicinal purposes.
Louis-Victor-Pierre-Raymond de Broglie was born into a noble French family. He initially studied history at the Sorbonne in Paris, intending to enter the diplomatic service.
Sir James Dewar was born in Kincardine, Scotland, on September 20, 1842, the son of an innkeeper. He attended local schools until he was ten when he suffered a serious case of rheumatic fever lasting two years.