Dispersion. Refers to a reducing of solids or liquids to minute particles in some medium to prepare powders, suspensions, emulsions. Used to obtain colloidal systems and disperse system in general.

Displacement reaction.  A chemical reaction in which an atoms or groups displace another atom or group from a molecule, e.g., iron displaces copper from CuSO₄ solution.
CuSO₄+Fe ---> FeSO₄ + Cu¯
  (aq.)   (S)        (aq.)       (S)

Donor. The atoms ion or molecule that gives the pair of electron in forming a covalent Bond.

Doping. The name given to the practice whereby electrical, magnetic and other properties of a solid may be changed by incorporation of impurities in the host lattice. E.g. the incorporation of small amounts of Li+ or Ga₃+ into the nickel oxide lattice results in a respective decrease or increase in conductivity of the latter. Incorporation of e.g. B in Si forms useful semi-conductors. When the dopant is not incorporation directly into the lattice, but rather forms discrete aggregations within it, the process is referred to as domain doping.
Double bound. Atoms can share two pairs of electrons forming a double bond (two covalent bonds). Ethene.

Has a double bond. A double bond is stronger than a single bond although more reactive. Formally a double bond generally arises from overlap of p-orbitals of two atoms which are already unite by overlap of s orbitals. See pi bond, sigma bond.