Quiz today over Covalent bonding
Need to turn in all missing work today!
• Take out your lab. Staple it together but
don’t turn it in the basket. I am going to
collect them from you when the bell rings.
• Take out your Molecular Shape Lab. We
are going to finish it.
• DCA next class!
Which bond is more polar: (find the
electronegativity difference)
A) H-S
B) H-O
C) H-Si
Name that bond!
1. What type of bond(s) does KCl have?
2. What type of bond(s) does KOH have?
3. What type of bond(s) does K have?
• http://phet.colorado.edu/en/simulation/mol
ecule-shapes
VSEPR THEORY:
•How do we determine
the shapes of molecules
and ions?
VSEPR THEORY
• What does VSEPR stand
for?
• Valence Shell Electron Pair
Repulsion
• Electrons repel each other just like
magnets!
Molecular geometries
• Lewis structures help us understand the type
of bonds between atoms in a molecule
• But, they do NOT indicate the geometry in 3-D
space.
• VSEPR theory helps describe the actual
geometry of molecules based on their
covalent bonding.
VSEPR Theory
• Valence Shell Electron Pair Repulsion
Theory
• Electrons repel one another so they try to
be as FAR AWAY from each other as
possible
• This determines the shape (think 3D)
C. Johannesson
VSEPR Theory
• Lone pairs reduce the bond angle between
atoms.
Bond Angle
C. Johannesson
VSEPR THEORY (VALENCE SHELL ELECTRON REPULSION)
NO CENTRAL ATOM
LINEAR SHAPE (ALL DIATOMICS ARE LINEAR :H2 N2 O2 and ALL OF GROUP 7A)
2 ATOMS AROUND A CENTRAL ATOM
LINEAR SHAPE ( BF2
HCN )
UNBONDED
OF ELECTRONS
ON CENTRAL ATOM
BENT SHAPE
( H2O H2PAIR
S NO
2) )
TRIGONAL PLANAR SHAPE
( BF3
3 ATOMS AROUND A CENTRAL ATOM
UNBONDED ELECTRONS ON CENTRAL ATOM
TRIGONAL PYRAMIDAL
( NH3
H3As )
4 ATOMS AROUND A CENTRAL ATOM
TETRAHEDRAL SHAPE ( CCl4 CF4
CH4 )
25 min review
15 min finish quiz
20 min metallic bonding
30 min quiz
• Allow 15 minutes to finish up the “lab”
• Talk about bond strength- triple is the
strongest
• Give example of KNO3 has both an ionic
bond and a covalent bond while KCl is
ionic and K is just metallic
• Look for the Jump Street 21 clip… 
• http://www.bsc2.ehbschweiz2.ch/Chemie/Simulationen%20Ch
emie/Bindung/Bindung%20Hundeanalogie
.htm
Polar Covalent bonds
• Polar = unequal sharing of electrons due
to electronegative difference
• This creates a “partial positive charge” and
“partial negative charge”
• Separation of charge creates a dipole.
• https://www.youtube.com/watch?v=PVL24
HAesnc&index=23&list=PL8dPuuaLjXtPH
zzYuWy6fYEaX9mQQ8oGr
• Polar bond acts as a dipole.
• Dipole = electronic vector with a
magnitude and a direction.
•
• Equal in magnitude and opposite direction
cancel to give nonpolar molecule.
For a molecule to be polar, 2
conditions must both be met
1.
There must be at least one polar bond or one lone (unshared)
pair on the central atom.
And
2. A. The polar bonds, if there are more than one, must not
be arranged so that their polarities (bond dipoles) cancel.
Or
B. If there are two or more lone (unshared) pairs on the
central atom, they must not be arranged so that their
polarities cancel.
• Which bond is more polar, HCl or HBr?
Hybridization
• A new set of orbitals (hybrid orbitals) are
created by mixing s, p, and d (if needed).
Hybridization
• http://www.youtube.com/watch?v=g1fGXD
RxS6k
To understand how molecules really are:
• https://www.youtube.com/watch?v=cPDptc
0wUYI&list=PL8dPuuaLjXtPHzzYuWy6fY
EaX9mQQ8oGr&index=25
You now have 15 minutes to finish your
VSEPR “Quiz” with your group
Quiz Time!