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  2. Allenes - Wikipedia

    en.wikipedia.org/wiki/Allenes

    In organic chemistry, allenes are organic compounds in which one carbon atom has double bonds with each of its two adjacent carbon atoms (R 2 C=C=CR 2, where R is H or some organyl group). [1] Allenes are classified as cumulated dienes. The parent compound of this class is propadiene (H 2 C=C=CH 2), which is itself also called allene.

  3. Azide - Wikipedia

    en.wikipedia.org/wiki/Azide

    In chemistry, azide (/ ˈ eɪ z aɪ d /, AY-zyd) is a linear, polyatomic anion with the formula N − 3 and structure − N=N + =N −. It is the conjugate base of hydrazoic acid HN 3. Organic azides are organic compounds with the formula RN 3, containing the azide functional group. [1] The dominant application of azides is as a propellant in ...

  4. List of chemical elements - Wikipedia

    en.wikipedia.org/wiki/List_of_chemical_elements

    A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...

  5. Periodic table - Wikipedia

    en.wikipedia.org/wiki/Periodic_table

    It is an icon of chemistry and is widely used in physics and other sciences. It is a depiction of the periodic law, which states that when the elements are arranged in order of their atomic numbers an approximate recurrence of their properties is evident. The table is divided into four roughly rectangular areas called blocks. Elements in the ...

  6. Glossary of chemistry terms - Wikipedia

    en.wikipedia.org/wiki/Glossary_of_chemistry_terms

    Also acid ionization constant or acidity constant. A quantitative measure of the strength of an acid in solution expressed as an equilibrium constant for a chemical dissociation reaction in the context of acid-base reactions. It is often given as its base-10 cologarithm, p K a. acid–base extraction A chemical reaction in which chemical species are separated from other acids and bases. acid ...

  7. Ylide - Wikipedia

    en.wikipedia.org/wiki/Ylide

    An ylide (/ ˈ ɪ l aɪ d /) [1] or ylid (/ ˈ ɪ l ɪ d /) is a neutral dipolar molecule containing a formally negatively charged atom (usually a carbanion) directly attached to a heteroatom with a formal positive charge (usually nitrogen, phosphorus or sulfur), and in which both atoms have full octets of electrons.

  8. Promethium - Wikipedia

    en.wikipedia.org/wiki/Promethium

    In forming compounds, the atom loses its two outermost electrons and one 4f-electron, which belongs to an open subshell. The element's atomic radius is the second largest among all the lanthanides but is only slightly greater than those of the neighboring elements. [ 5 ]

  9. Group 6 element - Wikipedia

    en.wikipedia.org/wiki/Group_6_element

    Group 6, numbered by IUPAC style, is a group of elements in the periodic table. Its members are chromium (Cr), molybdenum (Mo), tungsten (W), and seaborgium (Sg). These are all transition metals and chromium, molybdenum and tungsten are refractory metals .