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  2. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    The formal charge of an atom is computed as the difference between the number of valence electrons that a neutral atom would have and the number of electrons that belong to it in the Lewis structure. Electrons in covalent bonds are split equally between the atoms involved in the bond.

  3. Dissociation (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Dissociation_(chemistry)

    Dissociation in chemistry is a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into other things such as atoms, ions, or radicals, usually in a reversible manner. For instance, when an acid dissolves in water, a covalent bond between an electronegative atom and a hydrogen atom is broken by ...

  4. Chemical structure - Wikipedia

    en.wikipedia.org/wiki/Chemical_structure

    Chemical structure. A chemical structure of a molecule is a spatial arrangement of its atoms and their chemical bonds. Its determination includes a chemist 's specifying the molecular geometry and, when feasible and necessary, the electronic structure of the target molecule or other solid. Molecular geometry refers to the spatial arrangement of ...

  5. History of molecular theory - Wikipedia

    en.wikipedia.org/wiki/History_of_molecular_theory

    History of molecular theory. Space-filling model of the H 2 O molecule. In chemistry, the history of molecular theory traces the origins of the concept or idea of the existence of strong chemical bonds between two or more atoms. A modern conceptualization of molecules began to develop in the 19th century along with experimental evidence for ...

  6. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    It is determined by the number of bonds it can form to other atoms or groups. [92] The outermost electron shell of an atom in its uncombined state is known as the valence shell, and the electrons in that shell are called valence electrons. The number of valence electrons determines the bonding behavior with other atoms.

  7. Discovery of nuclear fission - Wikipedia

    en.wikipedia.org/wiki/Discovery_of_nuclear_fission

    The nuclear reaction theorised by Meitner and Frisch and observed by Hahn and Strassmann. Nuclear fission was discovered in December 1938 by chemists Otto Hahn and Fritz Strassmann and physicists Lise Meitner and Otto Robert Frisch. Fission is a nuclear reaction or radioactive decay process in which the nucleus of an atom splits into two or ...

  8. History of atomic theory - Wikipedia

    en.wikipedia.org/wiki/History_of_atomic_theory

    History of atomic theory. The current theoretical model of the atom involves a dense nucleus surrounded by a probabilistic "cloud" of electrons. Atomic theory is the scientific theory that matter is composed of particles called atoms. The definition of the word "atom" has changed over the years in response to scientific discoveries.

  9. Bond order - Wikipedia

    en.wikipedia.org/wiki/Bond_order

    The bond order itself is the number of electron pairs (covalent bonds) between two atoms. [2] For example, in diatomic nitrogen N≡N, the bond order between the two nitrogen atoms is 3 (triple bond). In acetylene H–C≡C–H, the bond order between the two carbon atoms is also 3, and the C–H bond order is 1 (single bond).