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  2. Eutrophication - Wikipedia

    en.wikipedia.org/wiki/Eutrophication

    Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water. [1] [2] Eutrophication may occur naturally or as a result of human actions.

  3. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    A chemical bond is the association of atoms or ions to form molecules, crystals, and other structures. The bond may result from the electrostatic force between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds, or some combination of these effects.

  4. Nutrient pollution - Wikipedia

    en.wikipedia.org/wiki/Nutrient_pollution

    Nutrient pollution, a form of water pollution, refers to contamination by excessive inputs of nutrients.It is a primary cause of eutrophication of surface waters (lakes, rivers and coastal waters), in which excess nutrients, usually nitrogen or phosphorus, stimulate algal growth. [1]

  5. Rearrangement reaction - Wikipedia

    en.wikipedia.org/wiki/Rearrangement_reaction

    In organic chemistry, a rearrangement reaction is a broad class of organic reactions where the carbon skeleton of a molecule is rearranged to give a structural isomer of the original molecule. [1] Often a substituent moves from one atom to another atom in the same molecule, hence these reactions are usually intramolecular. In the example below ...

  6. AP Chemistry - Wikipedia

    en.wikipedia.org/wiki/AP_Chemistry

    The 2014 AP Chemistry exam was the first administration of a redesigned test as a result of a redesigning of the AP Chemistry course. The exam format is now different from the previous years, with 60 multiple choice questions (now with only four answer choices per question), 3 long free response questions, and 4 short free response questions.

  7. Covalent bond - Wikipedia

    en.wikipedia.org/wiki/Covalent_bond

    A covalent bond forming H 2 (right) where two hydrogen atoms share the two electrons. A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. These electron pairs are known as shared pairs or bonding pairs.

  8. Dead zone (ecology) - Wikipedia

    en.wikipedia.org/wiki/Dead_zone_(ecology)

    Red circles show the location and size of many dead zones (in 2008). Black dots show dead zones of unknown size. The size and number of marine dead zones—areas where the deep water is so low in dissolved oxygen that sea creatures cannot survive (except for some specialized bacteria)—have grown in the past half-century.

  9. Double bond rule - Wikipedia

    en.wikipedia.org/wiki/Double_bond_rule

    Moreover, the multiple bonds of the elements with n=2 are much stronger than usual, because lone pair repulsion weakens their sigma bonding but not their pi bonding. [2] An example is the rapid polymerization that occurs upon condensation of disulfur, the heavy analogue of O 2. Numerous exceptions to the rule exist. [3]