enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Present perfect - Wikipedia

    en.wikipedia.org/wiki/Present_perfect

    The present perfect is a grammatical combination of the present tense and perfect aspect that is used to express a past event that has present consequences. [1] The term is used particularly in the context of English grammar to refer to forms like "I have finished".

  3. Pentagonal bipyramidal molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Pentagonal_bipyramidal...

    Structure of iodine heptafluoride, an example of a molecule with the pentagonal-bipyramidal coordination geometry. In chemistry, a pentagonal bipyramid is a molecular geometry with one atom at the centre with seven ligands at the corners of a pentagonal bipyramid. A perfect pentagonal bipyramid belongs to the molecular point group D 5h.

  4. Covalent bond - Wikipedia

    en.wikipedia.org/wiki/Covalent_bond

    Bonds with one or three electrons can be found in radical species, which have an odd number of electrons. The simplest example of a 1-electron bond is found in the dihydrogen cation, H + 2. One-electron bonds often have about half the bond energy of a 2-electron bond, and are therefore called "half bonds".

  5. Bonding in solids - Wikipedia

    en.wikipedia.org/wiki/Bonding_in_solids

    As this example shows, there can be no sharp boundary between molecular and network covalent solids. Intermediate kinds of bonding: A solid with extensive hydrogen bonding will be considered a molecular solid, yet strong hydrogen bonds can have a significant degree of covalent character. As noted above, covalent and ionic bonds form a continuum ...

  6. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    The bond results because the metal atoms become somewhat positively charged due to loss of their electrons while the electrons remain attracted to many atoms, without being part of any given atom. Metallic bonding may be seen as an extreme example of delocalization of electrons over a large system of covalent bonds, in which every atom ...

  7. Tetrahedral molecular geometry - Wikipedia

    en.wikipedia.org/wiki/Tetrahedral_molecular_geometry

    In a tetrahedral molecular geometry, a central atom is located at the center with four substituents that are located at the corners of a tetrahedron.The bond angles are arccos(− ⁠ 1 / 3 ⁠) = 109.4712206...° ≈ 109.5° when all four substituents are the same, as in methane (CH 4) [1] [2] as well as its heavier analogues.

  8. Ionic bonding - Wikipedia

    en.wikipedia.org/wiki/Ionic_bonding

    Ionic bonding is a type of chemical bonding that involves the electrostatic attraction between oppositely charged ions, or between two atoms with sharply different electronegativities, [1] and is the primary interaction occurring in ionic compounds.

  9. Chemical compound - Wikipedia

    en.wikipedia.org/wiki/Chemical_compound

    The differences in the types of bonds in compounds differ based on the types of elements present in the compound. London dispersion forces are the weakest force of all intermolecular forces . They are temporary attractive forces that form when the electrons in two adjacent atoms are positioned so that they create a temporary dipole .