Chemistry- Chemical Bonds

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Chemistry- Chemical Bonds
2011-01-18 21:21:55
Chapter Chemistry chemical bonds

Chemistry chapter 10 12 and 14 notes
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  1. What is a chemical bond - Briefly explain two types
    An electrical force of attraction between atoms to form molecules. Ionic- completely transfered; Covalent- shared electrons
  2. Why do atoms bond?
    • To become isoelectronic to the inert gases...
    • Why the inert gases? Because they are chemically stable...
    • How do we know the inert gases are stable? They dont chemically combine, high IE, 0 electron affinity, no electronegativity...
    • What makes them stable? 8 valence electrons
  3. Explain in detail an ionic bond
    • Na1 >> Cl7
    • 1) Energy is supplied - sodium loses an electron (Na has a low ionization energy)
    • 2) Na is now a cation - Na+1 (also isoelectronic to neon)
    • 3) Free electron goes to chlorine- Cl has a high electron affinity
    • 4) Cl is now an anion - Cl-1 (also isoelectronic to argon
    • 5)Opposite ions attract
    • 6) Electron stays with Cl - Cl has a high electron negativity
  4. Changes in ionic bond for different elements
    • For some elements there is not a 1:1 ratio
    • Na 1>>> O 6 Na2O
    • Na 1>>>>^
  5. Ionization Energy - def. trends, why, highest and lowest 1st and 2nd
    • Definition- The energy required to remove an electron from an atom
    • Trends and why- increase up (shielding effect) and increase across (closer to 8 valence electrons)
    • Highest IE- 1st: He 2nd: Li+1
    • Lowest IE- 1st: Fr 2nd Ra+1
  6. Electronegativity- def. trends, why, highest and lowest 1st and 2nd
    • Definition- Attraction for electrons after it has bonded
    • Trends increase up (shielding effect) increase left (close to the stable 8) and none for noble gases (they don't form compounds)
    • Highest 1st: Flourine 2nd: Oxygen
    • Lowest 1st: inert gases 2nd: Francium
  7. Electrolyte- why important in the body
    A substance that in dissolved or molten form conducts electricity. They help send signals throughout the body
  8. Three definitions of valence
    • 1)A number telling the combining capacity of an element
    • 2)The # of valence electrons in excess are lacking from the stable set of 8
    • 3) The charge in the ion after losing or gaining electrons
  9. Explain with sample - pure, polar, double, triple covalent bond (lewis dot diagram)
    • Pure- share the electrons equally
    • Polar- electrons are not shared equally
    • Double and Triple- Atoms share 2 (or 3) pair of valence electrons H-C=C-H
  10. Hybrid orbital - show example
    • A mixture of orbitals formed during a covalent bond
    • H H
    • H-C-C-H
    • H H
  11. Properties of ionic and covalent compounds
    • Ionic- (1) White (2) Crystalline (3) Solid (4) High m.p. (5)High b.p. (6) dissolves in water (7) electrolyte
    • Covalent- (1) Any state (2) Any color (3) Low m.p. (4) Low b.p. (5) non-soluble (6) non-electrolyte
  12. Define hydrocarbon, unsaturated, dipole moment, shielding effect
    • Hydrocarbon- Contains hydrogen and carbon
    • Unsaturated- has at least one double or triple covalent bond
    • Dipole moment- a measure of the charge distribution of a dipole
    • Shielding effect- inner electrons blocking the valence electrons from the nucleus