1. No category

Lewis Structures Notes
•
Draw the dot diagram for each atom. Make sure you place the electrons in the correct order.
•
Draw the dot diagrams for Carbon, Nitrogen and Oxygen.
•
Steps for drawing Lewis Structures:
o Order the atoms- the atom with the most unpaired electrons will be the central atom
(Carbon is always the central atom).
o Draw the dot diagram for each element in the compound.
o Pair up all unpaired electrons.
•
Examples:
o Phosphorous and Chlorine (PCl3)
o Carbon and Bromine (CBr4)
• Ionic Dot Diagrams- the electrons are gained and lost, not shared. Put each atom in a bracket
with its balance electrons around it. The charge of the atom goes outside of the bracket.
o Ex: Sodium Chloride (NaCl)
Unit 6: Bonding and Nomenclature
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Ionic Lewis Structure Activity
In this activity we will be modeling what an Ionic Bond is using cereal to represent the valence
electrons. Please follow the following steps for modeling what occurs in the following ionic
compounds:
1. Draw the element’s symbols in the designated box.
2. Assign the proper number of valance electrons (Cereal) to each original element
3. Make an ionic bond to create a balanced neutral compound by moving a valence electron
(Cereal)
4. Draw the correct Lewis Structure in the box below.
5. Write the formula or name of the compound.
KBr
Magnesium chloride
CaO
Lithium oxide
Mg3N2
Sodium Sulfide
Fe2O3
Silver Nitrate
PbS2
Unit 6: Bonding and Nomenclature
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Covalent Bonding Notes
•
Covalent bonds are between _____________________________________________.
•
Covalent bonds are formed when electrons are _____________________ between two atoms.
If two atoms share 4 electrons, they form a ______________________________. If two atoms
share 6 electrons, they form a ____________________________.
•
There are two types of covalent bonds: polar and non-polar. Polar bonds have an
electronegativity difference between ___________________________. Non-polar bonds have
an electronegativity difference less than ___________________.
•
In polar bonds, the electrons are shared ________________________________. In non-polar
bonds, the electrons are shared ________________________________.
•
Covalent compounds can exist in any state (solid, liquid or gas). They have _____________
melting and boiling points.
•
Write the correct formulas for each covalent compound:
Compound Name
water
Carbon Dioxide
Chlorine (Diatomic Element)
Methane (5 total atoms)
Ammonia (4 total atoms)
Carbon tetrabromide (5 total
atoms)
Phosphorous trichloride (4 total
atoms)
Diphosphorous trioxide (5 total
atoms)
Unit 6: Bonding and Nomenclature
Oxidation States
O (-2)
H (+1)
C (+4)
O (-2)
Covalent Formula
Cl (-1)
C (-4)
H (+1)
N (-3)
H (+1)
C (+4)
Br (-1)
P (-3)
Cl (-1)
P (-3)
O (-2)
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Polyatomic Ions
• Ions formed from a single atom are known as
ions.
• You wrote formulas for ionic compounds using monoatomic ions. Many ionic and
covalent compounds found in chemistry contain polyatomic ions, which are ions
made up of
.
• Practice writing ionic formulas using polyatomic ions:
BaCO3
Al2(SO4)3
Zn(ClO)2
Pb(C2H3O2)2
Cobalt (III) Nitrate
Ammonium Chloride
Silver Chlorate
Barium Phosphate
• How would you write the formula for calcium hydroxide?
.
Is there a difference between CaOH2 & Ca(OH)2 ? Circle the correct formula.
• When more than one polyatomic ion is present, the formula for the polyatomic
ion is surrounded by
Unit 6: Bonding and Nomenclature
.
Page 15
Covalent Lewis Activity
In this activity we will be modeling what a Covalent Bond is using cereal to represent the valence
electrons. Please follow the following steps for modeling what occurs in the following ionic
compounds:
1. Draw the element’s symbols in the designated box.
2. Assign the proper number of valance electrons (cereal) to each original element
3. Make a covalent bond to create a balanced neutral compound.
4. Draw the correct Lewis Structure in the box below.
5. Mark with stars the compounds that are diatomic.
CO2
H2 O
NH3
F2
O2
N2
ClO3
PO3
SO2
Unit 6: Bonding and Nomenclature
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Lewis Dot Structure Worksheet
Here are the basic steps involved in drawing the Lewis dot structure for a molecule:
a) Calculate the total number of valence electrons in the molecule (take the number of valence
electrons for each atom and add them together).
b) Draw the electrons around each atom. Put the atom that normally forms the most bonds in
the center.
c) Each single bond contains 2 electrons.
In the spaces below, draw the Lewis structure for each molecule. Each molecule contains only single
bonds. Write the total number of electrons for each molecule in the upper right corner.
H2 O
NH3
electrons
CH4O
CCl4
electrons
C2H6
electrons
Unit 6: Bonding and Nomenclature
electrons
OF2
electrons
electrons
Page 17
Now we are going to look at molecules that contain at least one double or triple bond.
In the spaces below, draw the Lewis structure for each molecule. Write the total number of electrons
for each molecule in the upper right corner.
O2
N2
electrons
SO3
CO2
electrons
electrons
PO4
electrons
electrons
Some chemical substances represent EXCEPTIONS to the octet rule. For example, boron trichloride has
a Lewis dot structure that only has three single bonds. The boron atom is surrounded by only 6
electrons instead of 8. Draw the Lewis structure for BCl3
BCl3
electrons
Unit 6: Bonding and Nomenclature
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Covalent Naming Notes
• Binary covalent compounds are characterized by having two nonmetals. Naming
these compounds involves the use of numerical prefixes:
Prefix
Number
Prefix
Number
1
6
2
7
3
8
4
9
5
10
• If there is only ONE atom of the first element, you DON’T need a prefix. The FIRST
element is named as a normal element. The SECOND element has an –IDE ending.
o N2O4
o XeF4
o N2O5
o CO
o CBr4
o Diarsenic pentoxide
o Phosphorous pentabromide
o Carbon tetraiodide
o Trisilicon tetranitride
o Tetraphosphorous decoxide
Unit 6: Bonding and Nomenclature
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Covalent Naming Worksheet
CO2
__________________________
NI3
__________________________ _____
CO
_________________________
SiBr4
____________________________
PCl5
__________________________
SF6
__________________________
N 2O
__________________________
As2O5
__________________________
N2O3
__________________________
Cl2S7
__________________________
B2Cl4
__________________________
P4O10
__________________________
nitrogen dioxide
sulfur hexabromide
carbon diselenide
diphosphorus trioxide
silicon tetrachloride
phosphorus trifluoride
dinitrogen tetrasulfide
Unit 6: Bonding and Nomenclature
___
___
arsenic pentafluoride
dibromine heptaoxide
xenon hexafluoride
Page 20
Naming Acids
• If the compound begins with Hydrogen, it is an acid. If the acid does not contain a
polyatomic ion, write the prefix hydro-, then name the second element and
change the ending to –ic.’
o HCl
o HBr
o H 2S
Naming Acids with Polyatomic Ions
The polyatomic ions you have memorized have –ate as the ending, so you name the polyatomic ion
and change the ending to –ic.
Use sulfate (SO42-) as the example
• H2SO4 is sulfuric acid
•
If the ion has one more oxygen atom than the base (SO42-), then the ion is named by adding the
prefix per- and the suffix –ic
o H2SO5 is persulfuric acid
•
If the ion has one less oxygen atom than the base (SO42-), then the ion is named with the
suffix –ous.
o H2SO3 is sulfurous acid
•
If the ion has two less oxygen atoms than the base (SO42-), then the ion is named with the prefix
hypo- and the suffix –ous.
o H2SO2 is hyposulfurous acid
Name the following:
1. H2CO3
2. H3PO2
3. HClO4
4. H3PO3
Unit 6: Bonding and Nomenclature
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VSPER- Valence Shell Electron Pair Repulsion
VSPER is used to describe the ____________ ___________ of molecules
Single, double, or triple bonds act ________________.
Unbonded electrons, ___________ ______________ of electrons take up more space than bonded
pairs of electrons.
Electron densities (lone pairs and bonds) will arrange themselves _____________ around an atom to
minimize repulsive forces.
Steps to determine geometry:
1. Draw the Lewis Structure
2. Count up the number of bonds on the central atom.
3. Look on the chart to find the shape (You will NOT have the chart on the test).
Bonds
Unit 6: Bonding and Nomenclature
Lone Pairs
Shape
Linear
Bent
Trigonal Planar
Trigonal Pyramidal
Tetrahedral
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VSEPR
Complete the table with the requested information.
Molecule
Structural Diagram
Oxidation State of
each element
Molecular
Geometry
CClF3
SF2
BF3
SiBr4
NH3
Unit 6: Bonding and Nomenclature
Page 23
Shapes and Bonding Orbitals Activity
Unit 6: Bonding and Nomenclature
Page 24
Unit 6: Bonding and Nomenclature
Page 25
Unit 6: Bonding and Nomenclature
Page 26
VSEPR Worksheet
1) What is the main idea behind VSEPR theory?
2)
For each of the following compounds, determine the bond angles, molecular shapes,
and hybridizations for all atoms:
a)
carbon tetrachloride
b)
BH3
c)
silicon disulfide
d)
C2H2
e)
PF3
Unit 6: Bonding and Nomenclature
Page 27