1. Ch. 12 Notes---Covalent Bonds
____________ electrons between two atoms in order to fill the outer energy level (or shell)
Each bond involves the sharing of _____ _________ of electrons.
Single Bonds= __ e-’s Double Bonds= __ e-’s Triple Bonds=__ e-’s
Sharing
one pair 2 4 6
Sharing
Sharing is Caring!!
Caring is Covalent!!!

2. Ways to Represent Covalent Bonds in Compounds
Quantum Mechanical or Bohr Model of the Atom.

3. Ways to Represent Covalent Bonds in Compounds
Quantum Mechanical or Bohr Model of the Atom.

4. Ways to Represent Covalent Bonds in Compounds
(2) “Dots” for bonds. (Lewis Structures)
a) H H · · H 
b) F :F· ·F: 
c) N :N · ·N:  (triple bond)
d) NH3
H:H .. .. .. ..
:F:F: .. .. .. ..
:N::N: ..
H:N:H .. H

5. Ways to Represent Covalent Bonds in Compounds
(3) “Lines” for bonds.
a) H2
b) F2
c) N2
d) NH3
e) H2O
H–H .. ..
:F–F: .. ..
:N≡N:
H–N–H ׀ H ..
H–O: ׀ H

6. Carbon’s Hybrid Orbital C …___ ___ ___ ___ (Before) 2s 2p↑ ↓ ↑ ↑
C …___ ___ ___ ___ (After: 4 covalent bonds available) ↑ ↓ ↑ ↑ ↑
2sp3
Practice Problem: Draw CH4 using arrows, dots, and lines for bonds.
C …___ ___ ___ ___ ↑ ↑ ↑ ↑
2sp3
H ___ 1s ↑
H ___ 1s ↑
H ___ 1s ↑
H ___ 1s ↑

7. “HONClBrIF” The 7 Diatomic Elements
Some elements will covalently bond to themselves to form a molecule composed of ____ atoms.
These elements are never found in nature as single atoms. Instead, they will be bonded as a ________ when they are in the “_________________” state.
The 7 diatomic elements are the gases H, O, N, and all of the _________________, (Group 7A).
H2, O2, N2, Cl2, Br2, I2, F2
“HONClBrIF”
two
pair
elemental
halogens

9. Air contains N2 and O2 molecules.

10. The decomposition of two water molecules

11. PCl5 (___ e-) SF6 (___ e-) BF3(___e-)
Octet Rule
Atoms want ___ e-’s in their outer shell when forming compounds.
This will mean ___ dots around them all together. This is the stable e- configuration of a __________ _______!
Important exception: Hydrogen = only needs __ to be full (like He).
Other Exceptions:
PCl5 (___ e-) SF6 (___ e-) BF3(___e-) 8 8
noble gas 2 10 12 6

12. VSEPR Theory: Molecular Shapes
Most shapes are based on a __________________.
Examples: CH4 CCl4
Removing the top of the tetrahedral makes the ________________ shape.
Examples: NH PCl3
tetrahedral
pyramidal

13. VSEPR Theory: Molecular Shapes
Removing one side of the pyramid makes the _____________ shape.
Examples: H2O H2S
If there are only two atoms bonded, it is ______________.
Examples: O2 HCl CO2 (linear because of its double bonds.)
bent
linear

14. VSEPR Theory: Molecular Shapes
Another we will need to know is called “trigonal planar”. “Trigonal” means that the central atom is bonded to ___ other atoms. “Planar” means that the 3 atoms all lie in the same ______________.
Example: BF3
(Notice that Boron will only have ___ e-’s around it. The missing pair of electrons will make it planar instead of ________________.) 3
plane 6
pyramidal

15. Polar and Nonpolar Bonds
Even though the electrons in a covalent bond are shared, sometimes the attraction for the bonded pair, (the _____________________), is uneven. This gives rise to 3 bond types.
nonpolar covalent bonds: ____________ sharing of the e- pair
polar covalent bonds: ________________ sharing of the e- pair
ionic bonds: a ___________ of e-’s from the metal to the nonmetal
How To Determine the Bond Type
Bond type is based on the electronegativity _____________ between the two bonded atoms.
electronegativity
equal
unequal
transfer
difference

17. Figure 12.4 The three possible types of bonds.
nonpolar
polar
ionic

18. Figure 12.4: Electronegativity values for selected elements.

19. How To Determine the Bond Type
0 to 0.4 = ______________ covalent bond
0.5 to 2.0 = _____________ covalent bond
Above 2.0 = _______________ bond
Practice Problems: Determine the type of bond that forms between the atoms in the following compounds.
a) CO2 b) NaCl c) CH4
nonpolar
polar
ionic
1.0 = polar covalent
2.1 = ionic
0.4 = nonpolar covalent

20. Polarity of Molecules
One side is slightly (__) and the other side is slightly (__).
Polar molecules are also known as _______________.
Polarity depends on the __________ and symmetry of the molecule.
symmetrical molecules (looks the same on all sides)= ___________
asymmetrical molecules = ___________
Polar molecules are moved by ____________ charges. (DEMO!) + –
dipole
shape
nonpolar
polar
static

21. a) CH4 b) NH3 c) H2O d) HCl e) BF3
Molecular Polarity
Practice Problems: Determine if the following molecules are polar or nonpolar based on their shape.
a) CH4 b) NH c) H2O d) HCl e) BF3
symmetrical tetrahedral
asymmetrical pyramid
asymmetrical bent
asymmetrical linear
symmetrical trigonal planar
nonpolar
polar
polar
polar
nonpolar
Dipole of NH3
Dipole of H2O

22. Bond Dissociation Energy
This is the energy needed to ___________ the bond.
Generally, the longer the bond, the _____ energy it takes to break it.
Single bonds take ________ energy to break than double bonds and triple bonds require the _________ energy to break.
When bonds form, energy is _____________.
(Breaking bonds requires the addition of energy.)
break
less
less
most
released

23. Bond Dissociation Energy

24. Intermolecular Attractions
The __________ attractions between one molecule and another are called _______ ______ ________ forces.
They cause gas particles to stick together and _______________ at low temperatures.
weak
Van der Waals
condense

25. Dispersion Forces
There are two types of intermolecular forces:
(1) ____________________ forces: (the weaker type)
caused by random _______________ motion
generally _____________ with ________ electrons in the molecule
Dispersion
electron
stronger
more
− exist between all
types of molecules
− This force causes
Br2 to be a liquid
and I2 to be a solid
at room temperature.

26. Dipole Interaction Forces
(2) ____________ interactions: (the stronger force)
caused by the attraction of the (__) side of one polar molecule and the (__) side of a different polar molecule
Dipole + –

27. Hydrogen Bonds
________________ “Bonds” are a special type of dipole interaction.
This attraction between molecules is not a chemical bond. Electrons are not being shared or transferred.
They occur between the hydrogen of one polar molecule and the ____, ___ or ___ of another polar molecule.
Hydrogen
N O F
Hydrogen Bonding
in Water

28. Hydrogen Bonds
The ladder rungs in a DNA molecule are hydrogen bonds between the base pairs, (AT and GC).

29. Hydrogen Bonds in DNA

30. Intermolecular Forces At Work
Substances that contain stong intermolecular forces have a ________ melting point and a _________ boiling point.
Liqids containing strong intermolecular forces have higher surface tension and a higher viscosity.
higher
higher

31. Surface Tension

32. Ionic Bonding & Ionic Compounds
Ionic Bonds
Form when ___________ transfer their _____________ electrons to a _______________.
The forces of attraction between the ____________ (+) and the _____________ (-) bind the compound together.
How to Represent an Ionic Bond
Electron Configuration:
Na 1s2 2s2 2p6 3s1
Cl 1s2 2s2 2p6 3s2 3p5
metals
valence
nonmetal
cation
anion
Na… ___ 3s ↑
Cl… ___ ___ ___ ___
3s p ↑ ↓ ↑ ↓ ↑ ↓ ↓

33. How to Represent an Ionic Bond
2) Bohr Model
Lithium
Fluorine

34. How to Represent an Ionic Bond
3) Electron Dot Notations:
Na Cl  [ ] [ ]
Practice Problems: (1) Draw the electron dot notation for the formation of an ionic compound between sodium and oxygen.
(2) Draw the electron configuration notation for the formation of an ionic compound between magnesium and fluorine.
Na+1
Cl -1

36. S [ S -2] K [K+1] Practice Problems:
3) a) Draw the electron dot notation for a potassium atom.
b) Draw the electron dot notation for a potassium ion.
(4) a) Draw the electron dot notation for a sulfur atom.
b) Draw the electron dot notation for a sulfur ion. K
[K+1] S
[ S -2]

37. Properties of Ionic Compounds and Covalent Molecules
_______________ of electricity when dissolved water or melted.
formed between __________ and _________________
have _________ melting points
usually ________ soluble in water
form ___________________ solids
Conductors
metals
nonmetals
high
(dissolved salt)
very
ionic crystalline

38. Crystalline Patterns

39. Pyrite
mineral form of the iron disulfide (FeS2) with a gold-like appearance, making it also known as "fool's gold"

40. Gypsum
Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O.

42. Properties of Ionic Compounds and Covalent Molecules
Molecular:
________________ of electricity
formed between two _______________
usually have ________ melting points
solubility in water _______: (polar =dissolve; nonpolar = insoluble)
forms ______________________solids.
For a compound to to conduct electricity it must have:
(1) Charged Particles (________)
(2) Particles Free to Move (___________ or __________ phase)
Insulators
nonmetals
low
varies
covalent crystalline
ions
liquid
aqueous

43. Quartz
Quartz is the common mineral form of silicon dioxide (SiO2). It is the dominant mineral in most sands and sandstones.

45. Demonstration PureH2O great conductor good conductor poor conductor
nonconductor