Do Now
Name …………………………………………….
Team ……………………….
Title: Atomic Chemistry
Date ………………………
Draw Lewis dot structures for each of the following
**C
**Al
**Si
S
**NH3
CO2
*CH4
CaCl2
Rapid Knowledge
Name …………………………………………….
Title:
Formula
Team ………………………
Date ………………………
What is the correct chemical formula for :
**Al with Cl
**Mg with O
**H with O
*Mg with SO4-
*Ca with SO4
*Li with SO4
H with PO4
Al with CO3-
Describe the trends in the Electronegativity found in the periodic table
Notes
Information Sheet
More explaining
Diagrams
Definitions quotes and
smart phrases
Equations
Key points
CFU for lecture 1
A covalent bond contains
A covalent triple bond contains
A molecule of nitrogen contains
Lecture 1 summary
Lecture Notes
More explaining
Diagrams
Definitions quotes and
smart phrases
Key points
Equations
Practice
Name ………………………………………
Title: VSEPR
Team ……………………….
Date ………………………
Paired work
*Write a summary of the key points about VSEPR theory?
*Arrange the following in decreasing order of repulsion for bonding pairs and lone pairs:
Bp-lp, bp-bp, lp-lp
Draw out the structure and write out the standard bond angle CH4
Independent work Draw out the structure and write out the standard bond
angle for each of the following shape of molecules
**
BF3
PF3
**
H2O
**
SF6
*
PCl5
*
NH3
Exit Ticket
1)
**
**
**
Name ……………………………………………
Team ……………………….
Title:Shapes of molecules
Date ………………………
For each of the following compounds, draw lewis structures and then
determine the bond angles, and molecular shapes.
a)
carbon tetrachloride
b)
BH3
c)
silicon disulfide
d)
C2H2
e)
PF3
SiS2
HWK
**
Name …………………………………………
Team ……………………….
Title:Q numbers and definitions
Date ………………………
II. Draw Lewis Structures for the following molecules predict the shapes and the
bond angles.
PCl3
**
CH4
**
CH3Br
*
F2O
*
IBr
NH2Cl
Deduce the shape of the molecule whose dot and cross diagram is shown above:
For the first 5 questions I will provide lewis dot structure and students will have to decide
on the shape and the bond angle
3 final questions will require students to draw lewis bond structures and decide on shape
and angles The energy of each Bohr orbit is quantized.
Molecules of Methane, CH4, ammonia, NH3, water, H2O and hydrogen fluoride, HF
The directional nature of covalent bonds is shown in the diagrams of molecules above. The shape of the
methane molecule is tetrahedral because the four bonding pairs of electrons repel each other equally, and
the equilibrium position of all four bonding electron pairs is tetrahedral.
How to work out the Shape of a Molecule
It is possible to work out the shape of a small molecule that has a formula XYn by applying a few simple
rules. We will use ammonia as an example to illustrate the idea.
The Shape of Ammonia, NH3


Rule 1. First find the number of bonding pairs of electrons in
the molecule. The number of bonding pairs of electrons in the
molecule NH3 can be seen in the formula. There must be
three bonding pairs of electrons holding the three hydrogens
onto the nitrogen.
Rule 2. Find the number of valence electrons (electrons in
the outer energy level) on an atom of the central atom (The
one of which there is only one.) Nitrogen is in group V, so the
The Shape of
Ammonia




nitrogen has five electrons in the outer energy level.
Rule 3. Find the number of lone pairs on the central atom by
subtracting the number of bonding pairs (3) from the valence
electrons (5) to find the number of electrons (2) that will make
up lone pairs of electrons. Divide this number by 2 to find the
number of lone pairs, 2/2 = 1.
Rule 4. Distribute all the electron pairs around the central
atom and learn the angles they will make from molecules
with no lone pairs.
Rule 5. Learn that the repulsion between lone pairs of
electrons is greater than the repulsion between bonding
pairs, and subtract 2o from the bond angles for every lone
pair.
Rule 6. Learn the names of the shapes. The shapes are
named form the position of the atoms and not the position of
the orbitals.
Table of Shapes
There is one more rule to learn, and it concerns the shape of polyatomic ions.
The Shape of Ammonia, NH3

Rule 2a. If the molecule is an ion, e.g. ammonium (NH4+), subtract 1 from the
number of valence electrons for every + charge on the ion and add 1 to the
valence number for every - charge, then proceed as before.
Some more Examples
Molecular Shapes &
VSEPR
(Only consider molecules of 3 atoms or more)
Molecular geometry derived from following basic
shapes:
Valence shell electron pair repulsion theory (VSEPR) is able to predict
shapes!
1, 2, or 3 pairs of electrons between 2 atoms called electron domain.
There are 2 types of domains:
1. BONDING DOMAIN
All electrons within a given single, double, or triple bond are in the same
domain
2. NONBONDING DOMAIN
Pair of electrons associated with a single atom (lone pair)
VSEPR
Electron Domains
Total
2
3
3
4
4
4
5
5
5
5
6
6
6
Bonding Non-bonding
2
3
2
4
3
2
5
4
3
2
6
5
4
0
0
1
0
1
2
0
1
2
3
0
1
2
Molecular Geometry
linear
triangular-planar
bent
tetrahedral
trigonal pyramidal
bent
trigonal bipyramidal
seesaw
T-shaped
linear
octahedral
square-pyramidal
square-planar
Examples
CO2 BeF2
BF3
NO3-1
CCl2 NO2-1
CH4
NH4+1
NH3
CH3-1
H2O
NH2-1
PCl5 SF5+1
SF4
IF4+1
ClF3 SF3-1
XeF2 SF2-2
SF6 PCl6-1
BrF5 SF5-1
XeF4 SF4-2