Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds composed of atoms, molecules and ions: their composition, structure, properties, behavior and the changes they undergo during a reaction with other substances.
In chemistry, an element is a pure substance consisting only of atoms that all have the same numbers of protons in their atomic nuclei. Unlike chemical compounds, chemical elements cannot be broken down into simpler substances by chemical means. The number of protons in the nucleus is the defining property of an element, and is referred to as its atomic number – all atoms with the same atomic number are atoms of the same element. All of the baryonic matter of the universe is composed of chemical elements. When different elements undergo chemical reactions, atoms are rearranged into new compounds held together by chemical bonds. Only a minority of elements, such as silver and gold, are found uncombined as relatively pure native element minerals. Nearly all other naturally-occurring elements occur in the Earth as compounds or mixtures. Air is primarily a mixture of the elements nitrogen, oxygen, and argon, though it does contain compounds including carbon dioxide and water.
Chemical engineering is a certain type of engineering which deals with the study of operation and design of chemical plants as well as methods of improving production. Chemical engineers develop economical commercial processes to convert raw material into useful products. Chemical engineering uses principles of chemistry, physics, mathematics, biology, and economics to efficiently use, produce, design, transport and transform energy and materials. The work of chemical engineers can range from the utilization of nanotechnology and nanomaterials in the laboratory to large-scale industrial processes that convert chemicals, raw materials, living cells, microorganisms, and energy into useful forms and products. Chemical engineers are involved in many aspects of plant design and operation, including safety and hazard assessments, process design and analysis, modeling, control engineering, chemical reaction engineering, nuclear engineering, biological engineering, construction specification, and operating instructions.
A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei, and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.
A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs. These are limited to a single typographic line of symbols, which may include subscripts and superscripts. A chemical formula is not a chemical name, and it contains no words. Although a chemical formula may imply certain simple chemical structures, it is not the same as a full chemical structural formula. Chemical formulae can fully specify the structure of only the simplest of molecules and chemical substances, and are generally more limited in power than chemical names and structural formulae.
A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are distinguished from ions by their lack of electrical charge.
The periodic table, also known as the periodic table of elements, is a tabular display of the chemical elements, which are arranged by atomic number, electron configuration, and recurring chemical properties. The structure of the table shows periodic trends. The seven rows of the table, called periods, generally have metals on the left and nonmetals on the right. The columns, called groups, contain elements with similar chemical behaviours. Six groups have accepted names as well as assigned numbers: for example, group 17 elements are the halogens; and group 18 are the noble gases. Also displayed are four simple rectangular areas or blocks associated with the filling of different atomic orbitals.
The Chemical Brothers are an English electronic music duo formed by Tom Rowlands and Ed Simons in Manchester in 1989. They were pioneers in bringing the big beat genre to the forefront of pop culture. They released their debut album Exit Planet Dust (1995) and it eventually went on to sell over a million copies worldwide. After attracting Virgin Records, the duo achieved more widespread success with their second album Dig Your Own Hole (1997), which topped the UK charts. In the UK, they have had six No. 1 albums and 13 Top 20 singles, including two No. 1 hits.
Mustard gas, though technically not a gas and often called sulfur mustard by scholarly sources, is the prototypical substance of the sulfur-based family of cytotoxic and vesicant chemical warfare agents, which can form large blisters on exposed skin and in the lungs. It has a history of use as a blister-agent in warfare and, along with organoarsenic compounds such as Lewisite, is the most well-studied of such agents. Related chemical compounds with similar chemical structure and similar properties form a class of compounds known collectively as sulfur mustards or mustard agents. Pure sulfur mustards are colorless, viscous liquids at room temperature. When used in impure form, such as warfare agents, they are usually yellow-brown and have an odor resembling mustard plants, garlic, or horseradish, hence the name. The common name of "mustard gas" is inaccurate because the sulfur mustard is not actually vaporized, but dispersed as a fine mist of liquid droplets. Mustard gas was originally assigned the name LOST, after the scientists Wilhelm Lommel and Wilhelm Steinkopf, who developed a method of large-scale production for the Imperial German Army in 1916.
Chemical warfare (CW) involves using the toxic properties of chemical substances as weapons. This type of warfare is distinct from nuclear warfare, biological warfare and radiological warfare, which together make up CBRN, the military acronym for nuclear, biological, and chemical, all of which are considered "weapons of mass destruction" (WMDs). None of these fall under the term conventional weapons which are primarily effective due to their destructive potential. In theory, with proper protective equipment, training, and decontamination measures, the primary effects of chemical weapons can be overcome. In practice, they continue to cause much suffering, as most victims are defenseless. Many nations possess vast stockpiles of weaponized agents in preparation for wartime use. The threat and the perceived threat have become strategic tools in planning both measures and counter-measures.
A CAS Registry Number, also referred to as CASRN or CAS Number, is a unique numerical identifier assigned by the Chemical Abstracts Service (CAS) to every chemical substance described in the open scientific literature, including organic and inorganic compounds, minerals, isotopes, alloys, mixtures, and nonstructurable materials. CASRNs are generally serial numbers, so they do not contain any information about the structures themselves the way SMILES and InChI strings do.
My Chemical Romance is an American rock band from Newark, New Jersey. The band's current lineup consists of lead vocalist Gerard Way, guitarists Ray Toro and Frank Iero, and bassist Mikey Way. Founded by Gerard, Mikey, Toro, and Matt Pelissier, the band signed to Eyeball Records and released their debut album, I Brought You My Bullets, You Brought Me Your Love, in 2002. They signed with Reprise Records the next year and released their major-label debut, Three Cheers for Sweet Revenge, in 2004. Shortly after the album's release, Pelissier was replaced by Bob Bryar. A commercial success, the album was awarded platinum status over a year later.
The European Chemicals Agency is an agency of the European Union which manages the technical and administrative aspects of the implementation of the European Union regulation called Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH). ECHA is the driving force among regulatory authorities in implementing the EU's chemicals legislation. ECHA has to ascertain that companies comply with the legislation, advances the safe use of chemicals, provides information on chemicals and addresses chemicals of concern. It is located in Helsinki, Finland. ECHA is an independent and mature regulatory agency established by REACH. It is not a subsidiary entity of the European Commission.
This is the list of extremely hazardous substances defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act. The list can be found as an appendix to 40 C.F.R. 355. Updates as of 2006 can be seen on the Federal Register, 71 FR 47121.
A chemical substance is a form of matter having constant chemical composition and characteristic properties. Some references add that chemical substance cannot be separated into its constituent elements by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be simple substances, chemical compounds, or alloys. Chemical elements may or may not be included in the definition, depending on expert viewpoint.
A chemical compound is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds. A molecule consisting of atoms of only one element is therefore not a compound.
The molecular formula C9H11NO2 (molar mass: 165.18 g/mol, exact mass: 165.078979) may refer to:
A chemical weapon (CW) is a specialized munition that uses chemicals formulated to inflict death or harm on humans. According to the Organisation for the Prohibition of Chemical Weapons (OPCW), "the term chemical weapon may also be applied to any toxic chemical or its precursor that can cause death, injury, temporary incapacitation or sensory irritation through its chemical action. Munitions or other delivery devices designed to deliver chemical weapons, whether filled or unfilled, are also considered weapons themselves."
The CompTox Chemicals Dashboard is a freely accessible online database created and maintained by the U.S. Environmental Protection Agency (EPA). The database provides access to multiple types of data including physicochemical properties, environmental fate and transport, exposure, usage, in vivo toxicity, and in vitro bioassay. EPA and other scientists use the data and models contained within the dashboard to help identify chemicals that require further testing and reduce the use of animals in chemical testing. The Dashboard is also used to provide public access to information from EPA Action Plans, e.g. around perfluorinated alkylated substances.,
