valence

Business

(noun)

A value assigned to an object, behavior, or other consequence that has relative scale.

Related Terms

  • Expectancy
  • Valence
  • Instrumentality
  • self-efficacy
  • instrumentality
  • expectancy theory
Chemistry

(noun)

The combining capacity of an atom, radical or functional group determined by the number of electrons that it will lose, gain, or share when it combines with other atoms, etc.

Related Terms

  • electronegativity
Management

(noun)

A one-dimensional value assigned to an object, situation, or state that can usually be positive or negative.

Related Terms

  • stock option
  • expectancy
  • instrumentality
  • expectancy theory

Examples of valence in the following topics:

  • Writing Lewis Symbols for Atoms

    • Since we have established that the number of valence electrons determines the chemical reactivity of an element, the table orders the elements by number of valence electrons.
    • Each of these elements has one valence electron.
    • Proceeding to the column labeled 'III', we find that those elements (B, Al, Ga, In, ...) have three valence electrons in their outermost or valence level.
    • Helium (He), at the very top of this column is an exception because it has two valence electrons; its valence level is the first principal energy level which can only have two electrons, so it has the maximum number of electrons in its valence level as well.
    • Helium is one of the noble gases and contains a full valence shell.
  • Bonding in Coordination Compounds: Valence Bond Theory

    • Valence bond theory is used to explain covalent bond formation in many molecules.
    • Valence bond theory is a synthesis of early understandings of how chemical bonds form.
    • Valence bond structures are similar to Lewis structures, except where a single Lewis structure is insufficient, several valence bond structures can be used.
    • It is in this aspect of valence bond theory that we see the concept of resonance.
    • Calculate the theoretical hybridization of a metal in a coordination complex based on valence bond theory
  • Choice

    • Schiefele (1991) identified two components of interest: feeling-related and value-related valences.
    • Feeling-related valences are feelings attached to a topic.
    • Value-related valences relate to the importance of the topic to an individual.
    • Feeling-related valences are the degree of enjoyment that an individual has toward a topic or object.
    • These feeling-related valences can be factors that enhance the motivation of learning.
  • Representing Valence Electrons in Lewis Symbols

    • Lewis symbols use dots to visually represent the valence electrons of an atom.
    • Chemical reactivity of all of the different elements in the periodic table depends on the number of electrons in that last, outermost level, called the valence level or valence shell.
    • In the case of gold, there is only one valence electron in its valence level.
    • Only the electrons in the valence level are shown using this notation.
    • Each of the four valence electrons is represented as a dot.
  • Chemical Bonding & Valence

    • Transfer of the lone 3s electron of a sodium atom to the half-filled 3p orbital of a chlorine atom generates a sodium cation (neon valence shell) and a chloride anion (argon valence shell).
    • These illustrations use a simple Bohr notation, with valence electrons designated by colored dots.
    • Non-bonding valence electrons are shown as dots.
    • The number of valence shell electrons an atom must gain or lose to achieve a valence octet is called valence.
    • From the formulas written above, we arrive at the following general valence assignments:
  • Formal Charge and Lewis Structure

    • The total number of valence electrons in the entire compound is equal to the sum of the valence electrons of each atom in the compound.
    • Non-valence electrons are not represented when drawing the Lewis structures.
    • Valence electrons are placed as lone pairs (two electrons) around each atom.
    • For example, CO2 is a neutral molecule with 16 total valence electrons.
    • FC = 6 valence electrons - (4 non-bonding valence electrons + 4/2 electrons in covalent bonds)
  • Introduction to Lewis Structures for Covalent Molecules

    • In covalent molecules, atoms share pairs of electrons in order to achieve a full valence level.
    • Eight electrons fill the valence level for all noble gases, except helium, which has two electrons in its full valence level.
    • Other elements in the periodic table react to form bonds in which valence electrons are exchanged or shared in order to achieve a valence level which is filled, just like in the noble gases.
    • Notice that only the outer (valence level) electrons are involved, and that in each F atom, 6 valence electrons do not participate in bonding.
    • Four covalent bonds are formed so that C has an octet of valence electrons, and each H has two valence electrons—one from the carbon atom and one from one of the hydrogen atoms.
  • Covalent Bonds

    • A fluorine atom has seven valence electrons.
    • Carbon will then have five valence electrons (its four and the one its sharing with fluorine).
    • Covalent bonds are a class of chemical bonds where valence electrons are shared between two atoms, typically two nonmetals.
    • A fluorine atom has seven valence electrons.
    • Carbon will then have five valence electrons (its four and the one its sharing with fluorine).
  • Analysis of Molecular Formulas

    • The number of hydrogen atoms that can be bonded to a given number of carbon atoms is limited by the valence of carbon.
    • The presence of oxygen (valence = 2) does not change this relationship, so the previously described C4H10O isomers follow the rule, n=4 & 2n + 2 = 10.
    • Halogen atoms (valence = 1) should be counted equivalent to hydrogen, as illustrated by C3H5Cl3, n = 3 & 2n + 2 = 8 = (5 + 3).
    • If nitrogen is present, each nitrogen atom (valence = 3) increases the maximum number of hydrogens by one.
    • For stable organic compounds the total number of odd-valenced atoms is even.
  • The Shielding Effect and Effective Nuclear Charge

    • The shielding effect explains why valence shell electrons are more easily removed from the atom.
    • The more shielding that occurs, the further the valence shell can spread out.
    • The outer energy level is n = 3 and there is one valence electron.
    • The valence shell is shell 2 and contains 8 valence electrons.
    • Thus the number of nonvalence electrons is 2 (10 total electrons - 8 valence).
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