UNIT 6 - CHEMICAL BONDING

INTRODUCTION TO CHEMICAL BONDING
ITypes of Chemical Bonding
    A.
  ____________________: mutual electrical attraction between the nuclei and valence e- of different atoms
         that binds the atoms together
    B.  Why do atoms bond together?
        1.  Atoms by themselves have ______ potential energy
        2.  Want to have ______ P.E. (this is what happens in nature)
        3.  Atoms are ____________________ alone than combined with other atoms
    C.  Electrons are ____________________ during bonding
    D.  Types of chemical bonding
        1.
  ____________________: results from attraction between large numbers of cations and anions
            a.  ____________________: positive ion;  atom that has lost e-
            b.  ____________________: negative ion;  atom that has gained e-
        2.  ____________________: results from sharing of e- pairs between two atoms
    E.  Determining Ionic or Covalent Bond (Official Way)
        1.
  Remember ____________________? (how much an atom wants to gain an e-)
        2.  Difference in EN tells whether bond is ionic or covalent
            a.  EN difference ____________________ (50% or less ionic character) = COVALENT
                1.  _______________COVALENT:  EN difference ______ to ______  (5 - 50% ionic character)
                2.  _______________ COVALENT: EN difference ______ to ______  (< 5% ionic character)
            b.  EN difference greater than ______ (> than 50% ionic character) = IONIC
    F.  Determining Ionic or Covalent Bond (Easy Way)
        1.
  ____________________: metal & nonmetal in formula
        2.  ____________________: 2 or more nonmetals
            a.  ____________________:  2 different nonmetals
            b.  ____________________: 2 of the same nonmetal

COVALENT BONDING AND MOLECULAR COMPOUNDS
I.  Molecules & Molecular Formulas
    A.
  ____________________: neutral group of atoms held together by covalent bonds -- (ex. one H2O)
    B.  _________________Molecule: molecule that contains only two atoms (of the same element)
         -->  there are only 7 of them;  they are 

II.  Formation of a Covalent Bond
    A.  2 separate atoms far enough away ____________________________________________ on each other
    B.  As they move ______________, the _______________ (+ chrg.) attracts the ______________ from the
         other atom & vice versa (________________ P.E.)
    C.  When atoms get too close, the + chrgs. in nucleus repel each other;  + chrgs. from other nucleus & e-
         repel each other also (increase in P.E.)

III.  Characteristics of the Covalent Bond
    A.  ____________________:  distance between 2 bonded atoms at their minimum P.E.
        1.  In other words, avg. distance between 2 bonded atoms
        2.  Measured in _______________ (pm) = 1 x 10-   m
    B.  Amt. of energy released when a bond is formed is ______________ to the difference in P.E. from separate
         atoms to the minimum P.E.
    C.  Same amt. of energy must be added to ____________________
    D.  ____________________: energy required to break a chemical bond & form isolated atoms
        1.  measured in _______________
        2.  kJ = _________ J (J = Joule, measure of energy)

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