IB Chemistry Power Points                                 Topic 4                                Bondingwww.pedagogics.ca ...
COVALENT BONDINGDefinition   consists of a shared pair of electrons with one electron being             supplied by each a...
COVALENT BONDING - EXCEPTIONS• atoms share electrons to get the nearest noble gas electronic configuration                ...
HYDROGEN          H                            H Hydrogen atom needs        Another hydrogen atom    one electron to      ...
HYDROGEN                          H     H                 atoms share a pair of electrons to                    form a sin...
HYDROGEN CHLORIDE       Cl                     H  Chlorine atom      Hydrogen atom alsoneeds one electron    needs one ele...
HYDROGEN CHLORIDE         Cl        Hatoms share a pair of electrons to form asingle covalent bond      WAYS TO REPRESENT ...
METHANE      WAYS TO REPRESENT                 H        THE MOLECULEEach hydrogen atom needs 1    H   H   electron to  com...
AMMONIA   WAYS TO REPRESENT     THE MOLECULE                   HEach hydrogen                          N    H atom needs  ...
WATER WAYS TO REPRESENT    THE MOLECULEEach hydrogen atom needs          Hone electron to                          O compl...
OXYGEN and NITROGEN   O                   O            O           Oeach atom needs two electrons   each oxygen shares 2 o...
Orbital theory – bond length and bond strengthCovalent bonds are formed when orbitals, each containing oneelectron, overla...
Multiple BondsCOMPARE Bond lengths and strengths (databook)O–O              0.148              146O=O      0.121          ...
Bond Polarity Consider a covalent bond between A and B. If A and B have the same electronegativity, the electrons are shar...
SIMPLE COVALENT MOLECULESBonding         Atoms are joined together within the molecule by covalent bonds.Electrical      D...
Lewis Structures and bonding – the Chem Prof            +         -    Try NH4 and NO2
2012   topic 4.1 bonding - covalent
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2012 topic 4.1 bonding - covalent

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  • FYI, your one hybridization slide (which I am about to use soon) sets the bar
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  • Dear David
    I am glad that you find my chemistry resources useful. I must disagree with your statement of 'much taken from my Knockhardy Powerpoint' . I would say all, or most, wouldn't you!
    At least you have given me credit for the work; that is more than most people do.
    All the best, Jonathan Hopton (I can also be contacted via my website).
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2012 topic 4.1 bonding - covalent

  1. 1. IB Chemistry Power Points Topic 4 Bondingwww.pedagogics.ca LECTURE 2 Covalent Bonding
  2. 2. COVALENT BONDINGDefinition consists of a shared pair of electrons with one electron being supplied by each atom either side of the bond. compare this with dative covalent bonding atoms are held together because their nuclei which + have an overall positive charge + are attracted to the shared electronsFormation between atoms of the same element N2, O2, diamond, graphite between atoms of different elements CO2, SO2 on the RHS of the table; when one of the elements is in t CCl4, SiCl4 middle of the table; with head-of-the-group elements BeCl2 with high ionisation energies;
  3. 3. COVALENT BONDING - EXCEPTIONS• atoms share electrons to get the nearest noble gas electronic configuration NOT ALWAYS• some don’t achieve an “octet” as they haven’t got enough electrons ex Al in AlCl3 (why is this a covalent bond?)• others share only some - if they share all they will exceed their “octet” ex NH3 and H2O• atoms of elements in the 3rd period onwards can exceed their “octet” if they wish as they are not restricted to eight electrons in their “outer shell” ex PCl5 and SF6 (HL only)
  4. 4. HYDROGEN H H Hydrogen atom needs Another hydrogen atom one electron to also needs one electron tocomplete its outer shell complete its outer shell
  5. 5. HYDROGEN H H atoms share a pair of electrons to form a single covalent bond A hydrogen MOLECULE is formedWAYS TO REPRESENT THE MOLECULEH H H H
  6. 6. HYDROGEN CHLORIDE Cl H Chlorine atom Hydrogen atom alsoneeds one electron needs one electron to complete its to complete its outer outer shell shell
  7. 7. HYDROGEN CHLORIDE Cl Hatoms share a pair of electrons to form asingle covalent bond WAYS TO REPRESENT THE MOLECULE H Cl H Cl
  8. 8. METHANE WAYS TO REPRESENT H THE MOLECULEEach hydrogen atom needs 1 H H electron to complete its C H outer shell C H H H H H A carbon atom all 4 of4 Carbon shares needs its electrons to form 4 electrons to complete single covalent bonds its outer shell H C H H
  9. 9. AMMONIA WAYS TO REPRESENT THE MOLECULE HEach hydrogen N H atom needs N Hone electron to complete its H outer shellH H Nitrogen can only shareelectrons atom needs 3 3 of its H N H 5 to complete its outer shell electrons otherwise it will exceed the maximum of 8 H A LONE PAIR REMAINS
  10. 10. WATER WAYS TO REPRESENT THE MOLECULEEach hydrogen atom needs Hone electron to O complete its H O outer shell H H Oxygen atom needs 2 electrons Oxygen can only share 2 of its 6 to complete its outerit will electrons otherwise shell H O exceed the maximum of 8 2 LONE PAIRS REMAIN H
  11. 11. OXYGEN and NITROGEN O O O Oeach atom needs two electrons each oxygen shares 2 of its to complete its outer shell electrons to form a DOUBLE COVALENT BOND
  12. 12. Orbital theory – bond length and bond strengthCovalent bonds are formed when orbitals, each containing oneelectron, overlap. orbital orbital bonding orbital shape containing 1 containing 1 electron electron The greater the overlap the stronger the bond. The greater the overlap, the shorter the bond length.
  13. 13. Multiple BondsCOMPARE Bond lengths and strengths (databook)O–O 0.148 146O=O 0.121 496C–C 0.154 348C=C 0.134 612C≡C 0.120 837C–O 0.143 360C=O 0.122 743
  14. 14. Bond Polarity Consider a covalent bond between A and B. If A and B have the same electronegativity, the electrons are shared equally. A : BIf B is more electronegative than A, the sharedelectrons have a greater probability of being foundcloser to B. POLAR COVALENT + A : B -
  15. 15. SIMPLE COVALENT MOLECULESBonding Atoms are joined together within the molecule by covalent bonds.Electrical Don’t conduct electricity as they have no mobile ions or electronsSolubility Tend to be more soluble in organic solvents than in water; some are hydrolysedBoiling point Low - compared to ionic compounds intermolecular forces are weak; they increase as molecules get a larger surface area e.g. CH4 -161 C C2H6 - 88 C C3H8 -42 C as the intermolecular forces are weak, little energy is required to to separate molecules from each other so boiling points are low some boiling points are higher than expected for a given mass because you can get additional forces of attraction these concepts will be clarified and expanded on in later lessons
  16. 16. Lewis Structures and bonding – the Chem Prof + - Try NH4 and NO2

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