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  2. Molecule - Wikipedia

    en.wikipedia.org/wiki/Molecule

    Also carbohydrates, for example, have the same ratio (carbon:hydrogen:oxygen= 1:2:1) (and thus the same empirical formula) but different total numbers of atoms in the molecule. The molecular formula reflects the exact number of atoms that compose the molecule and so characterizes different molecules. However different isomers can have the same ...

  3. Lewis structure - Wikipedia

    en.wikipedia.org/wiki/Lewis_structure

    When Be is bonded with 2 other atoms, or when B and Al are bonded with 3 other atoms, they do not form full valence shells. Assume single bonds and use the actual bond number to calculate lone pairs. Expanded Octet (only occurs for elements in Groups 3-8) Bond calculation will provide too few bonds for the number of atoms in the molecule.

  4. Atoms in molecules - Wikipedia

    en.wikipedia.org/wiki/Atoms_in_molecules

    In quantum chemistry, the quantum theory of atoms in molecules (QTAIM), sometimes referred to as atoms in molecules (AIM), is a model of molecular and condensed matter electronic systems (such as crystals) in which the principal objects of molecular structure - atoms and bonds - are natural expressions of a system's observable electron density distribution function.

  5. Chemical formula - Wikipedia

    en.wikipedia.org/wiki/Chemical_formula

    The Hill system (or Hill notation) is a system of writing empirical chemical formulae, molecular chemical formulae and components of a condensed formula such that the number of carbon atoms in a molecule is indicated first, the number of hydrogen atoms next, and then the number of all other chemical elements subsequently, in alphabetical order ...

  6. Molecular orbital - Wikipedia

    en.wikipedia.org/wiki/Molecular_orbital

    As the two atoms become closer together, their atomic orbitals overlap to produce areas of high electron density, and, as a consequence, molecular orbitals are formed between the two atoms. The atoms are held together by the electrostatic attraction between the positively charged nuclei and the negatively charged electrons occupying bonding ...

  7. Chemical bond - Wikipedia

    en.wikipedia.org/wiki/Chemical_bond

    Covalent bonding of two hydrogen atoms to form a hydrogen molecule, H 2. In (a) the two nuclei are surrounded by a cloud of two electrons in the bonding orbital that holds the molecule together. (b) shows hydrogen's antibonding orbital, which is higher in energy and is normally not occupied by any electrons.

  8. Structural formula - Wikipedia

    en.wikipedia.org/wiki/Structural_formula

    Skeletal structural formula of Vitamin B 12.Many organic molecules are too complicated to be specified by a molecular formula.. The structural formula of a chemical compound is a graphic representation of the molecular structure (determined by structural chemistry methods), showing how the atoms are connected to one another. [1]

  9. Atom - Wikipedia

    en.wikipedia.org/wiki/Atom

    Most of the atoms that make up the Earth and its inhabitants were present in their current form in the nebula that collapsed out of a molecular cloud to form the Solar System. The rest are the result of radioactive decay, and their relative proportion can be used to determine the age of the Earth through radiometric dating.