Rubber - Chemistry Encyclopedia

Rubber is an elastomer—that is, a polymer that has the ability to regain its original shape after being deformed. Rubber is also tough and resistant to weathering and chemical attack.

Rubidium - Chemistry Encyclopedia

Rubidium is a soft, silvery alkali metal that reacts explosively with water.

Ruthenium - Chemistry Encyclopedia

Ruthenium was discovered in 1844 in ores extracted from the Ural Mountains in Russia by Karl Klaus, who named it after Ruthenia, the Latin name for Russia. Its abundance in Earth's crust is about 0.0001 ppm.

Rutherfordium - Chemistry Encyclopedia

Rutherfordium is the first transactinide element. It was discovered in 1969 by Albert Ghiorso and his coworkers, who carried out the reactions 249Cf (12C, 4n)→ 257Rf (half-life of approximately 3.8 seconds) and 249Cf(13C, 3n) [→] 259Rf (half-life of approximately 3.4 seconds).

Salt - Chemistry Encyclopedia

The word "salt" is a general chemical term that refers to ionic compounds formed when an acid reacts with a base.

Samarium - Chemistry Encyclopedia

In 1886, French chemist P. E.

Scandium - Chemistry Encyclopedia

Drawing on his periodic law and his categorization of the elements, Russian chemist Dimitri Mendeleev predicted the existence of element 21 in 1871. However, it was not until 1879 that Swedish chemist Lars Frederick Nilson identified the element scandium as part of a novel compound he had isolated.

Secondary Structure - Chemistry Encyclopedia

The secondary structure refers to the conformation present at a local region of a polypeptide. A few types of secondary structure are particularly stable and occur widely in proteins.

Selenium - Chemistry Encyclopedia

Selenium (from the Greek word selēnē—the Moon), discovered by Swedish chemist Jöns Jakob Berzelius in 1817, ranks thirty-fourth among elements in Earth's crust. It has six naturally occurring isotopes, a large number of allotropes (elemental forms), and in compounds has oxidation states −2, +4, and +6.

Semiconductors - Chemistry Encyclopedia

The development of semiconductors is clearly among the most significant technological achievements to evolve from the study of solid-state chemistry and physics. Aside from their well-known applications in computers and electronics, semiconductors are also used in a wide variety of optical devices such as lasers, light-emitting diodes, and solar panels.

Silicon - Chemistry Encyclopedia

Silicon is the second most abundant element in Earth's crust and mantle, after oxygen. It is the seventh most abundant element in the universe.

Silicone - Chemistry Encyclopedia

The term "silica" denotes the compound silicon dioxide, SiO2. It is a ubiquitous chemical substance with rich chemical, geological, and commercial importance.

Silver - Chemistry Encyclopedia

Silver is a precious metal and (like gold and copper) is classified as a coinage metal. The date of its discovery is not known, but it has been identified in jewelry, coins, and religious ornaments dating to more than 2,000 years ago from ancient civilizations in South America, Egypt, Mesopotamia, and China.

Soap - Chemistry Encyclopedia

Soaps are cleaning agents that are usually made by reacting alkali (e.g., sodium hydroxide) with naturally occurring fat or fatty acids. The reaction produces sodium salts of these fatty acids, which improve the cleaning process by making water better able to lift away greasy stains from skin, hair, clothes, and just about anything else.

Sodium - Chemistry Encyclopedia

Sodium is a soft, silvery alkali metal and reacts vigorously with water to generate hydrogen gas. The word sodium is derived from "sodanum" (a Medieval Latin name for a headache remedy), and "natrium" (Latin for "soda") is the origin of the element's symbol.

Solar Cells - Chemistry Encyclopedia

A solar cell is, in principle, a simple semiconductor✶ device that converts light into electric energy. The conversion is accomplished by absorbing light and ionizing crystal atoms, thereby creating free, negatively charged electrons and positively charged ions.

Solid State - Chemistry Encyclopedia

Matter is commonly encountered in one of three states—solid, liquid, or gas. Air is an example of a gas and water an example of a liquid.

Solid-State Devices - Chemistry Encyclopedia

Solid-state devices are the controlling components of both high-tech and very ordinary devices. Their widespread usage is related to the fact that they can be utilized to interface with all human senses.

Solution Chemistry - Chemistry Encyclopedia

The majority of chemical processes are reactions that occur in solution. Important industrial processes often utilize solution chemistry.

Spectroscopy - Chemistry Encyclopedia

Spectroscopy is the measurement of interactions between electromagnetic radiation and matter. Electromagnetic radiation, which includes light, has characteristics of waves and particles.

Ernest Rutherford - Chemistry Encyclopedia

Ernest Rutherford was born on August 30, 1871, near Nelson, New Zealand. He was a very good student, excelling at science and mathematics.

Johannes Rydberg - Chemistry Encyclopedia

Johannes Robert Rydberg was born in Halmstad, Sweden, on November 8, 1854. His father, Sven, was a local merchant and minor shipowner who died when Rydberg was young.

Frederick Sanger - Chemistry Encyclopedia

Frederick Sanger is surely one of the most outstanding biochemists of modern times. His methods for determining the exact sequence of amino acids in proteins and of nucleotides in deoxyribonucleic acid (DNA) have won him numerous awards, including two Nobel Prizes in chemistry.

Carl Scheele - Chemistry Encyclopedia

Carl Wilhelm Scheele was born in Pomerania (on the Baltic coast of northeastern Europe, then under Swedish control). As a young man Scheele worked as an apothecary and studied chemistry under the famous chemist Torbern Bergman.

Erwin Schrödinger - Chemistry Encyclopedia

Erwin Schrödinger was born in Vienna, Austria, in 1887. In 1906 he entered the University of Vienna with the intention of studying statistical thermodynamics with the mathematician and physicist Ludwig Boltzmann.

Glenn Theodore Seaborg - Chemistry Encyclopedia

Florence Seibert - Chemistry Encyclopedia

Florence Seibert made several important contributions to medicine during her long career. Most notably, she purified a protein from tuberculosis bacteria that became the international standard for tuberculosis testing.

Frederick Soddy - Chemistry Encyclopedia

Frederick Soddy, the youngest of seven sons of a London corn merchant, was born on September 2, 1877, in Eastbourne, England. Raised by his half-sister, this precocious scientist attended Eastbourne College (1892–1894) and the University College of Wales, Aberystwyth (1895).