ChlorineChlorine is a chemical element with the symbol Cl and atomic number 17. The second-lightest of the halogens, it appears between fluorine and bromine in the periodic table and its properties are mostly intermediate between them. Chlorine is a yellow-green gas at room temperature. It is an extremely reactive element and a strong oxidising agent: among the elements, it has the highest electron affinity and the third-highest electronegativity on the revised Pauling scale, behind only oxygen and fluorine.
Dissolved organic carbonDissolved organic carbon (DOC) is the fraction of organic carbon operationally defined as that which can pass through a filter with a pore size typically between 0.22 and 0.7 micrometers. The fraction remaining on the filter is called particulate organic carbon (POC). Dissolved organic matter (DOM) is a closely related term often used interchangeably with DOC. While DOC refers specifically to the mass of carbon in the dissolved organic material, DOM refers to the total mass of the dissolved organic matter.
Hydroxyl radicalThe hydroxyl radical is the diatomic molecule •OH. The hydroxyl radical is very stable as a dilute gas, but it decays very rapidly in the condensed phase. It is pervasive in some situations. Most notably the hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water. It is also important in the field of radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments.
Ozone layerThe ozone layer or ozone shield is a region of Earth's stratosphere that absorbs most of the Sun's ultraviolet radiation. It contains a high concentration of ozone (O3) in relation to other parts of the atmosphere, although still small in relation to other gases in the stratosphere. The ozone layer contains less than 10 parts per million of ozone, while the average ozone concentration in Earth's atmosphere as a whole is about 0.3 parts per million.
Colored dissolved organic matterColored dissolved organic matter (CDOM) is the optically measurable component of dissolved organic matter in water. Also known as chromophoric dissolved organic matter, yellow substance, and gelbstoff, CDOM occurs naturally in aquatic environments and is a complex mixture of many hundreds to thousands of individual, unique organic matter molecules, which are primarily leached from decaying detritus and organic matter. CDOM most strongly absorbs short wavelength light ranging from blue to ultraviolet, whereas pure water absorbs longer wavelength red light.
Chlorine trifluorideChlorine trifluoride is an interhalogen compound with the formula . This colorless, poisonous, corrosive, and extremely reactive gas condenses to a pale-greenish yellow liquid, the form in which it is most often sold (pressurized at room temperature). Despite being famous for its extreme oxidation properties and igniting many things, chlorine trifluoride is not combustible itself.
Radical (chemistry)In chemistry, a radical, also known as a free radical, is an atom, molecule, or ion that has at least one unpaired valence electron. With some exceptions, these unpaired electrons make radicals highly chemically reactive. Many radicals spontaneously dimerize. Most organic radicals have short lifetimes. A notable example of a radical is the hydroxyl radical (HO·), a molecule that has one unpaired electron on the oxygen atom. Two other examples are triplet oxygen and triplet carbene (꞉CH2) which have two unpaired electrons.
Free-radical additionIn organic chemistry, free-radical addition is an addition reaction which involves free radicals. The addition may occur between a radical and a non-radical, or between two radicals. The basic steps with examples of the free-radical addition (also known as radical chain mechanism) are: Initiation by a radical initiator: A radical is created from a non-radical precursor.
Hydroxy groupIn chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry, alcohols and carboxylic acids contain one or more hydroxy groups. Both the negatively charged anion , called hydroxide, and the neutral radical , known as the hydroxyl radical, consist of an unbonded hydroxy group. According to IUPAC definitions, the term hydroxyl refers to the hydroxyl radical () only, while the functional group is called a hydroxy group.
Ozone depletionOzone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events.
