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Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
Covalent Electronegativity And Polarity Final
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Covalent Electronegativity And Polarity Final

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  • 1. Electronegativity and Polarity
  • 2. Electron Affinity
    • Measure of the tendency of an atom to attract electrons
    • Increases as atomic number increases in period
    • Decreases as you move down a group
    • Electronegativity
      • Indicates relative ability of an element’s atoms to attract electrons in a chemical bond
  • 3. Electronegativity
    • Not measure quantities…just numerical values assigned by Linus Pauling to compare the ability of atoms to attract shared electrons
    • Highest electronegative is F (3.98)
    • Lowest electronegative is Fr (0.7)
    • Noble gases generally do not form compounds
    • Exception: Larger noble gases (Xe, Rn)
    • Table on page 263
  • 4.  
  • 5. How we use electronegativity
    • Chemical bonds are never completely ionic or covalent because shared electrons are attracted to each other differently
    • Unequal sharing of electrons occurs because difference of electronegativities
    • Differences in electronegativity between two atoms can be used to predict the character and type of chemical bond formed between two atoms
  • 6.
    • Identical atoms have EN difference of zero
      • Electrons equally shared
      • Non-Polar Covalent bond (pure)
    • Polar Covalent Bonds
      • Unequal sharing of electrons between atoms of different elements
    • Ionic Bond
      • Large difference in EN between atoms indicates electron was transferred in a bond
    • Increase difference in EN  bond becomes more IONIC
    • EN difference 1.70 = 50% ionic and 50% covalent
    • EN difference >1.70 = IONIC
      • Exception: two nonmetals bonding
  • 7. POLAR COVALENT BONDS
    • Unequal sharing of electrons in a covalent bond
    • Tug-of-war
    • Electrons being shared spend more time around the EN atom than the other atom in the bond
    • Results in partial charges
      • δ + and δ -
      • POLARITY
    • More EN atom in the bond has the partially negative charge
    • Less EN atom in the bond has the partially positive charge
    • Dipole
      • Resulting polar bond between two different atoms in a covalent bond
  • 8.  
  • 9. Molecular Polarity
    • Polar molecules  attracted to electric field
    • Non-polar molecules  not attracted to electric field
    • Symmetrical molecular shapes  NON-POLAR (usually)
    • Asymmetrical molecules  POLAR as long as bond type is polar
  • 10.  
  • 11. Examples
    • Polar or non-polar molecules?
    • CCl 4
    • H 2 O
    • SCl 2
    • H 2 S
    • CF 4
    • CS 2
    • NH 3
  • 12. Solubility
    • Ability of one substance to dissolve in another substance
    • Physical property
    • Determined by bond type and shape
    • Polar molecules soluble in polar substances
    • Non-polar molecules soluble in non-polar substances
  • 13. Properties of Covalent Compounds
    • Salt vs. sugar
    • Difference in properties result in difference of attractive forces
    • Bond of atoms in covalent molecule is strong
    • Bond between covalent molecules is weak
    • Physical properties due to intermolecular forces…
  • 14. Intermolecular Forces
    • Weak attractive forces between individual molecules
    • Van der Waals Forces
      • Non-polar
        • Dispersion force or induced dipole
        • Very weak
      • Polar
        • Stronger than dispersion
        • Dipole-dipole force
        • Positive end of one dipole is attracted to negative end of another dipole
      • Hydrogen bond
        • Strongest intermolecular force
        • Formed between hydrogen of one dipole to the fluorine, oxygen, or nitrogen of another dipole
  • 15.  
  • 16. Physical properties
    • Low melting/boiling points
    • Many molecular substances are gases or vaporize readily at room temp
    • Hardness due to weak intermolecular forces (paraffin)
    • Solids form weak crystal lattice
  • 17. Covalent Network Solids
    • Solid in which atoms are interconnected by network of covalent bonds
    • Quartz
    • Diamond
    • Network solids are different from molecular solids
      • Brittle
      • Non-conductors of heat and electricity
      • Very Hard

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