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Organic chemistry is the chemistry of carbon compounds. All organic compounds contain carbon; however, there are some compounds of carbon that are not classified as organic.
Organic halogen compounds are a large class of natural and synthetic chemicals that contain one or more halogens (fluorine, chlorine, bromine, or iodine) combined with carbon and other elements. The simplest organochlorine compound is chloromethane, also called methyl chloride (CH3Cl).
Organometallic compounds have at least one carbon to metal bond, according to most definitions. This bond can be either a direct carbon to metal bond (σ bond or sigma bond) or a metal complex bond (π bond or pi bond).
The element osmium was discovered in 1804 by English chemist Smithson Tennant (1761–1815) in the black residue that remained after crude platinum was dissolved in aqua regia. The average abundance in Earth's crust is very low, about 0.005 grams (0.00018 ounces) per metric ton, and only four osmium-containing minerals, all extremely rare, are known: erlichmanite, OsS2; omeiite, (Os,Ru)As2; and osarsite and anduoite, (Os,Ru)AsS.
Joseph Priestley and Carl Scheele (each working independently) are credited with the isolation and "discovery" in 1774 of the element oxygen. A few years later Antoine Lavoisier showed that oxygen is a component of the atmosphere.
Earth's ozone layer plays a critical role in protecting Earth's surface from the Sun's harmful ultraviolet (UV) radiation. Every ozone molecule, which consists of three oxygen atoms, has the ability to absorb a certain amount of UV radiation.
The element palladium was isolated and identified by William Wollaston in 1803. Its name comes from the asteroid Pallas.
Paracelsus was born Theophrastus Bombastus von Hohenheim. He was a contemporary of Martin Luther and Nicolaus Copernicus.
Penicillin was discovered accidentally in 1929 when Sir Alexander Fleming observed bacterial cultures contaminated with a mold that inhibited bacterial growth. The antibiotic penicillin was subsequently isolated from cultures of the Penicillium mold.
A peptide bond is a linkage between the building blocks of proteins called amino acids (shorter strings of linked amino acids are known as peptides). A peptide bond forms when the carboxylic acid group (R-C[O]OH) of one amino acid reacts with the amine group (R-NH2) of another.
The Periodic Table places the symbols of chemical elements, sequenced by atomic number, in rows and columns that align similar properties.
Pesticides are chemicals that kill pests, and are categorized by the types of pests they kill. For example, insecticides kill insects, herbicides kill weeds, bactericides kill bacteria, fungicides kill fungi, and algicides kill algae.
Petroleum is a naturally occurring complex mixture made up predominantly of carbon and hydrogen compounds, but also frequently containing significant amounts of nitrogen, sulfur, and oxygen together with smaller amounts of nickel, vanadium, and other elements. Solid petroleum is called asphalt; liquid, crude oil; and gas, natural gas.
Pharmaceutical chemists are involved in the development and assessment of therapeutic compounds. Pharmaceutical chemistry encompasses drug design, drug synthesis, and the evaluation of drug efficacy (how effective it is in treating a condition) and drug safety.
Phospholipids are an important class of biomolecules. Phospholipids are the fundamental building blocks of cellular membranes and are the major part of surfactant, the film that occupies the air/liquid interfaces in the lung.
The element phosphorus is essential to living organisms. It is part of the backbone of DNA (deoxyribonucleic acid), the carrier and transmitter of genetic information in cells.
It has long been known that certain substances, when illuminated, undergo permanent visible changes.
No chemical process is more important to life on Earth than photosynthesis—the series of chemical reactions that allow plants to harvest sunlight and create carbohydrate molecules. Without photosynthesis, not only would there be no plants, the planet could not sustain life of any kind.
Physical chemistry is the branch of chemistry concerned with the interpretation of the phenomena of chemistry in terms of the underlying principles of physics. It lies at the interface of chemistry and physics, inasmuch as it draws on the principles of physics (especially quantum mechanics) to account for the phenomena of chemistry.
Pigments and dyes are called colorants. The ways in which colorants are used determines whether they are pigments or dyes.
The son of a wealthy New York City textile importer (Julius) and a painter (Elle Friedman), Julius Robert Oppenheimer enjoyed an affluent childhood. He graduated from the Ethical Culture School of New York at the top of his class in 1921 and summa cum laude from Harvard in 1925.
Friedrich Wilhelm Ostwald, born in Riga, Latvia, Russia, almost single-handedly established physical chemistry as an acknowledged academic discipline. In 1909 he was awarded the Nobel Prize in chemistry for his work on catalysis, chemical equilibria, and reaction velocities.
Fundamental particles are the elementary entities from which all matter is made. They have no known smaller parts.
Louis Pasteur was born in 1882 in Dole, France. Many people are unaware of the fact that he was a chemist.
Wolfgang Ernst Pauli was born in Vienna, Austria, where his father, regarded as one of the founders of colloid chemistry, was employed at the University of Vienna. His godfather was Ernst Mach, a famous physicist, philosopher, and one of the founders of logical positivism; he had a significant influence on Pauli's thinking.
Linus Carl Pauling was born in Portland, Oregon, on February 28, 1901, the first of three children of pharmacist Herman W. Pauling and Lucy Isabelle Pauling (née Darling).
William Henry Perkin was an entrepreneur and a self-made millionaire at an early age, long before the era of personal computers and dot-coms. His serendipitous synthesis of the purple dye mauve (also known as mauveine or aniline purple) in 1856 brought brightly colored clothing to the masses and laid the foundation for today's chemical and pharmaceutical industries.