molecularity

(noun)

Referring to the number of individual molecules involved in an elementary step of a reaction mechanism.

Related Terms

Examples of molecularity in the following topics:

  • Molecular Formulas

    • For example, for butane, the molecular formula is C4H10.
    • For example, the molecular formula of sodium fluoride is NaF.
    • A molecular formula is not a chemical name, and it contains no words.
    • The molecular formula for glucose is C6H12O6.
    • To convert between empirical and molecular formulas, the empirical formula can be multiplied by a whole number to reach the molecular formula.

  • A Structure Formula Relationship

    • Recall that the molecular formula of a hydrocarbon (CnHm) provides information about the number of rings and/or double bonds that must be present in its structural formula.
    • This molecular formula analysis may be extended beyond hydrocarbons by a few simple corrections.
    • All halogens present in the molecular formula must be replaced by hydrogen.

  • Polyatomic Molecules

    • The science of molecules is called molecular chemistry or molecular physics, depending on the focus.
    • Molecular chemistry deals with the laws governing the interaction between molecules resulting in the formation and breakage of chemical bonds; molecular physics deals with the laws governing their structure and properties.
    • In molecular sciences, a molecule consists of a stable system (bound state) comprising two or more atoms.
    • The molecular formula characterizes different molecules by reflecting their exact number of compositional atoms.
    • The empirical formula is often the same as the molecular formula, but not always; for example, the molecule acetylene has molecular formula C2H2, but the simplest integer ratio of elements is CH.

  • Naming Molecular Compounds

    • Molecular compounds are named using a systematic approach of prefixes to indicate the number of each element present in the compound.
    • Molecular compounds are made when two or more elements share electrons in a covalent bond to connect the elements.
    • Typically, non-metals tend to share electrons, make covalent bonds, and thus, form molecular compounds.
    • When naming molecular compounds prefixes are used to dictate the number of a given element present in the compound. " mono-" indicates one, "di-" indicates two, "tri-" is three, "tetra-" is four, "penta-" is five, and "hexa-" is six, "hepta-" is seven, "octo-" is eight, "nona-" is nine, and "deca" is ten.

  • Kinetic Molecular Theory and Gas Laws

    • Kinetic Molecular Theory explains the macroscopic properties of gases and can be used to understand and explain the gas laws.
    • The following are the basic assumptions of the Kinetic Molecular Theory:
    • According to Kinetic Molecular Theory, an increase in temperature will increase the average kinetic energy of the molecules.
    • Reviews kinetic energy and phases of matter, and explains the kinetic-molecular theory of gases.
    • Express the five basic assumptions of the Kinetic Molecular Theory of Gases.

  • Molecularity

    • When we describe the mechanism of a chemical reaction, it is important to identify the rate-determining step and to determine its "molecularity".
    • The molecularity of a reaction is defined as the number of molecules or ions that participate in the rate determining step.

  • Molecular Crystals

    • Molecules held together by van der Waals forces form molecular solids.
    • Molecular solids also have relatively low density and hardness.
    • The term "molecular solid" may refer not to a certain chemical composition, but to a specific form of a material.
    • White phosphorus forms molecular crystals composed of tetrahedral P4 molecules.
    • Conductivity of molecular solids can be induced by "doping" fullerenes (e.g., C60).

  • Table of Geometries

    • The VSPER theory detremines molecular geometries (linear, trigonal, trigonal bipyramidal, tetrahedral, and octahedral).
    • Molecular geometries (linear, trigonal, tetrahedral, trigonal bipyramidal, and octahedral) are determined by the VSEPR theory.
    • The table of molecular geometries can be found in the first figure.

  • Linear Combination of Atomic Orbitals (LCAO)

    • An LCAO approximation is a quantum superposition of atomic orbitals, used to calculate molecular orbitals in quantum chemistry.
    • These models provide a simple model of molecule bonding, understood through molecular orbital theory.
    • Essentially, n atomic orbitals combine to form n molecular orbitals.
    • Molecular orbital diagrams are diagrams of MO energy levels, shown as short horizontal lines in the center.
    • Predict which orbitals can mix to form a molecular orbital based on orbital symmetry, and how many molecular orbitals will be produced from the interaction of one or more atomic orbitals

  • Empirical Formulas

    • The molecular formula for a compound is equal to, or a whole-number multiple of, its empirical formula.
    • Its molecular weight is 142.286 g/mol.
    • What is the molecular formula of decane?
    • Step 1: Calculate the molecular weight of the empirical formula (the molecular weight of C = 12.011 g/mol and H = 1.008 g/mol)
    • Step 2: Divide the molecular weight of the molecular formula by the the molecular weight of the empirical formula to find the ratio between the two.