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CHEMICALBOND  (   PRESENTATION   )
BOND FORMATION   exothermic processEN     ReactantsER                                   EnergyG                          ...
BREAKING BONDS   Endothermic reaction     energy   must be put into the bond in order to break it     E     N           ...
BOND STRENGTH Strong, STABLE bonds require lots of energy to be  formed or broken weak bonds require little E
TWO MAJOR TYPES OF BONDINGIonic       Bonding   forms ionic compounds   transfer of e-Covalent             Bonding   ...
ONE MINOR TYPE OF BONDING Metallic   bonding Occurs   between like atoms of a metal  in the free state Valence e- are m...
It’s the mobileelectrons that enable  me tals to conduct      -    electricity!!!!!!
IONIC BONDING  electrons are transferred between valence shells of   atoms  ionic compounds are   made of ions          ...
IONIC BONDING   Always formed between metals and non-metals                       +                   -          [METALS ...
IONIC BONDING   Electronegativity difference > 2.0     Look   up e-neg of the atoms in the bond and subtract       NaCl ...
PROPERTIES OF IONIC COMPOUNDS                                            SALTS hard solid @ 22 C                 o       ...
COVALENT BONDINGPairs   of e- are shared                          molecules         between non-metal atomselectronegati...
MOLECULARSUBSTANCES                        Covalent                        bondingLow   m.p. temp and b.p. tempsrelative...
COVALENT, IONIC, METALLICBONDING?NO      2           NH +            • COsodium         4           Aluminu hydride   ...
DRAWING IONIC COMPOUNDSUSING LEWIS DOT STRUCTURES• Symbol represents the KERNEL of the  atom (nucleus and inner e-)• dots ...
NACL   This is the finished Lewis Dot Structure                                               -                  [Na] [ C...
 Step   1 after checking that it is IONIC Determine       which atom will be the +ion Determine       which atom will b...
DRAW THE LEWIS DIAGRAMS  LiF  MgO  CaCl          2  K S     2
DRAWING MOLECULES USINGLEWIS DOT STRUCTURES Symbol represents the KERNEL of the atom  (nucleus and inner e-) dots repres...
Always remember atoms are trying to complete their outer shell!The number of electrons the atoms needs is the total number...
METHANE CH4   This is the finished Lewis dot structure        How did we get here?
 Step   1  count       total valence e- involved Step  2  connect the central atom (usually the    first in the formul...
SOMETIMES . . . You only have two atoms, so there is no central  atom, but follow the same rules. Check & Share to make ...
 DOUBLE    bond atoms   that share two e- pairs (4 e-)               O O TRIPLE   bond atoms   that share three e- pai...
DRAW LEWIS DOT STRUCTURESYou may represent valence electrons from different atoms with the following symbols x, ,         ...
DIAGRAM FORPOLYATOMIC IONS Count all valence e- needed for covalent bonding Add or subtract other electrons based on the...
DRAW POLYATOMICS Ammonium Sulfate
TYPES OF COVALENTBONDSNON-Polar     bonds Electrons   shared evenly in the  bond E-neg difference is zero              ...
TYPES OF COVALENTBONDSPolar bond Electrons  unevenly shared E-neg difference greater than  zero but   less than 2.0  clo...
POLARITYWHICH IS LEAST AND WHICH ISMOST?HClCH       4CO                    a.k.a.       2                 “ionic charac...
NON-POLAR MOLECULESSometimes  the bonds withina molecule are polar and yetthe molecule is non-polarbecause its shape issy...
POLAR MOLECULES (A.K.A.DIPOLES)Not   equal on all sides  Polarbond between 2 atoms   makes a polar molecule  asymmetric...
δ+     H Cl   δ   -
SPACE FILLING MODEL“ELECTRON-CLOUD” MODEL    δ+    H     Cl       -                         δ
WATER IS ASYMMETRICAL          δ+           δ+         H             H               O                   -               δ
WATER IS A BENT MOLECULE  H                H       H          H      O
W-A-T-E-R    as bent as it can be!Water’s polar MOLECULE!Water’s polar MOLECULE!     The H is positive The O is not - not ...
MAKING SENSE OF THE POLARNON-POLAR THING    BONDS            MOLECULESNon-polar       Non-polar        Polar Polar        ...
IONIC BONDS ….Ionic bonds are                           so polar that the electrons arenot shared but transferred between ...
4 SHAPES OFMOLECULES
LINEAR (STRAIGHT LINE) Ball and stick model Space filling model
BENT Ball and stick model Space filling model
TRIGONAL PYRAMID Ball and stick    Space filling model             model
TETRAHEDRAL   Ball and stick   Space filling   model            model
INTERMOLECULAR ATTRACTIONS Attractions   between molecules   van  der Waals   forces     Weak attractive      forces be...
VAN DER WAALS   Non-polar molecules can exist in liquid and solid    phases      because van der Waals forces keep the mo...
VAN DER WAALS PERIODICITY increase      with molecular mass.  Greater    van der Waals force?      F2 Cl2 Br2 I2 incre...
HYDROGEN “BONDING” Strong polar attraction Like   magnets Occurs ONLY between H of one molecule and N, O, F of another ...
WHY DOES H “BONDING” OCCUR?   Nitrogen, Oxygen and Fluorine     small    atoms with strong nuclear charges          pow...
INTERMOLECULAR FORCESDICTATE CHEMICAL PROPERTIES   Strong intermolecular forces cause high b.p., m.p.    and slow evapora...
WHICH SUBSTANCE HAS THEHIGHEST BOILING POINT?    HF    NH       Fluorine has the highest e-neg,        3      H 2O   SO...
THE UNUSUAL PROPERTIES OF WATER Unusually high boiling point Compared to other compounds in Group 16
DENSITY????
H2O(S) IS LESS DENSE THAN H2O(L) The hydrogen bonding in water(l) molecules is random. The molecules are closely packed....
THE END
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Bonding

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Bonding

  1. 1. CHEMICALBOND ( PRESENTATION )
  2. 2. BOND FORMATION exothermic processEN ReactantsER EnergyG releasedY Products
  3. 3. BREAKING BONDS Endothermic reaction  energy must be put into the bond in order to break it E N Products E R Energy G Absorbed Y Reactants
  4. 4. BOND STRENGTH Strong, STABLE bonds require lots of energy to be formed or broken weak bonds require little E
  5. 5. TWO MAJOR TYPES OF BONDINGIonic Bonding  forms ionic compounds  transfer of e-Covalent Bonding  forms molecules  sharing e-
  6. 6. ONE MINOR TYPE OF BONDING Metallic bonding Occurs between like atoms of a metal in the free state Valence e- are mobile (move freely among all metal atoms) Positive ions in a sea of electrons Metallic characteristics  High mp temps, ductile, malleable, shiny  Hard substances  Good conductors of heat and electricity as (s) and (l)
  7. 7. It’s the mobileelectrons that enable me tals to conduct - electricity!!!!!!
  8. 8. IONIC BONDING  electrons are transferred between valence shells of atoms  ionic compounds are made of ions NOT MOLECULES • ionic compounds are called Salts or Crystals
  9. 9. IONIC BONDING Always formed between metals and non-metals + - [METALS ] [NON-METALS ] Lost e- Gained e-
  10. 10. IONIC BONDING Electronegativity difference > 2.0  Look up e-neg of the atoms in the bond and subtract NaCl CaCl2 Compounds with polyatomic ions NaNO3
  11. 11. PROPERTIES OF IONIC COMPOUNDS SALTS hard solid @ 22 C o Crystals high mp temperatures nonconductors of electricity in solid phase good conductors in liquid phase or dissolved in water (aq)
  12. 12. COVALENT BONDINGPairs of e- are shared molecules between non-metal atomselectronegativity difference < 2.0forms polyatomic ions
  13. 13. MOLECULARSUBSTANCES Covalent bondingLow m.p. temp and b.p. tempsrelatively soft solids as compared to ionic compoundsnonconductors of electricity in any phase
  14. 14. COVALENT, IONIC, METALLICBONDING?NO 2 NH + • COsodium 4 Aluminu hydride • CoHg m phosphateH S 2 KHsulfate Also study KCl your HF characteristics!
  15. 15. DRAWING IONIC COMPOUNDSUSING LEWIS DOT STRUCTURES• Symbol represents the KERNEL of the atom (nucleus and inner e-)• dots represent valence e-
  16. 16. NACL This is the finished Lewis Dot Structure - [Na] [ Cl ] How did we get here? +
  17. 17.  Step 1 after checking that it is IONIC Determine which atom will be the +ion Determine which atom will be the - ion Step 2 Write the symbol for the + ion first.  NO DOTS Draw the e- dot diagram for the – ion  COMPLETE outer shell Step 3 Enclose both in brackets and show each charge
  18. 18. DRAW THE LEWIS DIAGRAMS LiF MgO CaCl 2 K S 2
  19. 19. DRAWING MOLECULES USINGLEWIS DOT STRUCTURES Symbol represents the KERNEL of the atom (nucleus and inner e-) dots represent valence e-
  20. 20. Always remember atoms are trying to complete their outer shell!The number of electrons the atoms needs is the total number of bonds they can make.Ex. … H? O? F? N? Cl? C? one two one three one four
  21. 21. METHANE CH4 This is the finished Lewis dot structure How did we get here?
  22. 22.  Step 1 count total valence e- involved Step 2 connect the central atom (usually the first in the formula) to the others with single bonds Step 3 complete valence shells of outer atoms Step 4 add any extra e- to central atomIF the central atom has 8 valence e-
  23. 23. SOMETIMES . . . You only have two atoms, so there is no central atom, but follow the same rules. Check & Share to make sure all the atoms are “happy”. Cl2 Br2 H2 O2 N2 HCl
  24. 24.  DOUBLE bond atoms that share two e- pairs (4 e-) O O TRIPLE bond atoms that share three e- pairs (6 e-) N N
  25. 25. DRAW LEWIS DOT STRUCTURESYou may represent valence electrons from different atoms with the following symbols x, , CO2 NH3
  26. 26. DIAGRAM FORPOLYATOMIC IONS Count all valence e- needed for covalent bonding Add or subtract other electrons based on the chargeREMEMBER! A positive charge means it LOST electrons!!!!!
  27. 27. DRAW POLYATOMICS Ammonium Sulfate
  28. 28. TYPES OF COVALENTBONDSNON-Polar bonds Electrons shared evenly in the bond E-neg difference is zero Between identical atoms Diatomic molecules
  29. 29. TYPES OF COVALENTBONDSPolar bond Electrons unevenly shared E-neg difference greater than zero but less than 2.0 closer to 2.0 more polar more “ionic character”
  30. 30. POLARITYWHICH IS LEAST AND WHICH ISMOST?HClCH 4CO a.k.a. 2 “ionic character”NH 3N 2HF
  31. 31. NON-POLAR MOLECULESSometimes the bonds withina molecule are polar and yetthe molecule is non-polarbecause its shape issymmetrical. H H C H Draw Lewis dot first and see if equal on all sides H
  32. 32. POLAR MOLECULES (A.K.A.DIPOLES)Not equal on all sides Polarbond between 2 atoms makes a polar molecule asymmetrical shape of molecule
  33. 33. δ+ H Cl δ -
  34. 34. SPACE FILLING MODEL“ELECTRON-CLOUD” MODEL δ+ H Cl - δ
  35. 35. WATER IS ASYMMETRICAL δ+ δ+ H H O - δ
  36. 36. WATER IS A BENT MOLECULE H H H H O
  37. 37. W-A-T-E-R as bent as it can be!Water’s polar MOLECULE!Water’s polar MOLECULE! The H is positive The O is not - not - not - not
  38. 38. MAKING SENSE OF THE POLARNON-POLAR THING BONDS MOLECULESNon-polar Non-polar Polar Polar Symmetrical AsymmetricalIdentical Different
  39. 39. IONIC BONDS ….Ionic bonds are so polar that the electrons arenot shared but transferred between atoms forming ions!!!!!!
  40. 40. 4 SHAPES OFMOLECULES
  41. 41. LINEAR (STRAIGHT LINE) Ball and stick model Space filling model
  42. 42. BENT Ball and stick model Space filling model
  43. 43. TRIGONAL PYRAMID Ball and stick Space filling model model
  44. 44. TETRAHEDRAL Ball and stick Space filling model model
  45. 45. INTERMOLECULAR ATTRACTIONS Attractions between molecules  van der Waals forces  Weak attractive forces between non-polar molecules  Hydrogen “bonding”  Strong attraction between special
  46. 46. VAN DER WAALS Non-polar molecules can exist in liquid and solid phases because van der Waals forces keep the molecules attracted to each other Exist between CO2, CH4, CCl4, CF4, diatomics and monoatomics
  47. 47. VAN DER WAALS PERIODICITY increase with molecular mass.  Greater van der Waals force?  F2 Cl2 Br2 I2 increase with closer distance between molecules Decreases when particles are farther away
  48. 48. HYDROGEN “BONDING” Strong polar attraction Like magnets Occurs ONLY between H of one molecule and N, O, F of another H “bond”
  49. 49. WHY DOES H “BONDING” OCCUR? Nitrogen, Oxygen and Fluorine  small atoms with strong nuclear charges  powerful atoms  very high electronegativities
  50. 50. INTERMOLECULAR FORCESDICTATE CHEMICAL PROPERTIES Strong intermolecular forces cause high b.p., m.p. and slow evaporation (low vapor pressure) of a substance.
  51. 51. WHICH SUBSTANCE HAS THEHIGHEST BOILING POINT?  HF  NH Fluorine has the highest e-neg, 3  H 2O SO HF will experience the  WHY? strongest H bonding and ∴ needs the most energy to weaken the i.m.f. and boil
  52. 52. THE UNUSUAL PROPERTIES OF WATER Unusually high boiling point Compared to other compounds in Group 16
  53. 53. DENSITY????
  54. 54. H2O(S) IS LESS DENSE THAN H2O(L) The hydrogen bonding in water(l) molecules is random. The molecules are closely packed. Thehydrogen bonding in water(s) molecules has a specific open lattice pattern. The molecules are farther apart.
  55. 55. THE END

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