Chemistry is the scientific discipline involved with elements and compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.
In the scope of its subject, chemistry occupies an intermediate position between physics and biology. It is sometimes called the central science because it provides a foundation for understanding both basic and applied scientific disciplines at a fundamental level. For example, chemistry explains aspects of plant chemistry (botany), the formation of igneous rocks (geology), how atmospheric ozone is formed and how environmental pollutants are degraded (ecology), the properties of the soil on the moon (astrophysics), how medications work (pharmacology), and how to collect DNA evidence at a crime scene (forensics).
Chemistry addresses topics such as how atoms and molecules interact via chemical bonds to form new chemical compounds. There are four types of chemical bonds: covalent bonds, in which compounds share one or more electron(s); ionic bonds, in which a compound donates one or more electrons to another compound to produce ions (cations and anions); hydrogen bonds; and Van der Waals force bonds.
Lead(II) nitrate is the inorganic salt of nitric acid and lead. It is colourless crystal or white powder and a strong, stable oxidizer. Unlike most other lead(II) salts, it is soluble in water. Its main use from the Middle Ages under the name plumb dulcis, has been as raw material in the production of many pigments. Since the 20th century, it is industrially used as heat stabilizer in nylon and polyesters, and in coatings of photothermographic paper. Commercial production did not take place until the 19th century in Europe, and in the United States until after 1943, with a typical production process of metallic lead or lead oxide in nitric acid.
Lead(II) nitrate is toxic and probably carcinogenic to humans. It should therefore be handled and stored with the appropriate safety precautions. Ingestion may lead to acute lead poisoning: symptoms include intestinal malfunction, strong abdominal pains, appetite loss, nausea, vomiting and cramps, while longer-term exposure may lead to neurological and renal problems.
When lead(II) nitrate is heated, it decomposes to lead(II) oxide, accompanied by a crackling noise referred to as decrepitation. Due to this property, lead nitrate is sometimes used in pyrotechnics such as fireworks.
History and Philosophy of Chemistry
Wikipedia:WikiProject Chemicals/Data is a collection of links and references that are useful for chemistry-related works. This includes free online chemical databases, publications, patents, computer programs, and various tools.
Science is Fun
University of Wisconsin–Madison Chemistry Professor Bassam Z. Shakhashiri, shares the fun of science.
A good place to figure out what equals what.
General Chemistry Online
Clear text and comprehensive coverage of general chemistry topics by Fred Senese, Dept. of Chemistry Frostburg State University
General Chemistry Demonstration at Purdue
Video clips (and descriptions) of lecture demonstrations.
Intota Chemistry Experts
A large online listing of real-world chemistry expert biographies provides examples of the many areas of expertise and careers in chemistry.
Chemistry Webercises Directory
A large listing of chemistry resources maintained by Steven Murov, Emeritus Chemistry Professor Modesto Junior College.
MathMol (Mathematics and Molecules) is a good starting point for those interested in the field of molecular modeling.
Educational Resources and Essential References from Wiley, the world's largest chemistry publisher
A directory of free full-text journals in chemistry, biochemistry and related subjects.
The Element Song
A goofy little song about all of the elements.
(1893-1981) was an American physical chemist
, who won the 1934 Nobel Prize in Chemistry
for his work on isotopes
, specifically the discovery of deuterium
, a hydrogen
isotope, and the production of heavy water
. He also performed pioneering research in cosmochemistry
, which studies the origin and development of elements
and their isotopes, primarily within the solar system. Urey, along with his student Stanley Miller
, may be best remembered for the renowned Miller-Urey experiment
, which shows that a mixture of ammonia
, when exposed to ultraviolet radiation
, can interact to form amino acids
, the "building blocks" of terrestrial life. This experiment followed on from Urey's work on the oxygen
, and is considered to be pioneering work in the field of paleoclimatology
, as it attempts to explain the composition of the early Earth's atmosphere.
Techniques used by chemists
Equipment used by chemists
Chemistry in society
Chemistry in industry
Background color shows subcategory in the metal–metalloid–nonmetal trend:
Note: Nihonium, moscovium, tennessine, and oganesson have only recently been named.
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Collaboration of the Month
Every month a different chemistry-related topic, stub or non-existent article may be picked. Please improve the article any way you can.