GC Bonding.notebook
October 21, 2011
Chemical
Bonding
Oct 14­7:34 AM
What is a chemical bond...???
• a bond is made of electrons
• the electrons can be shared (covalent bonding)
or transferred (ionic bonding)
• it is the valence electrons that are involved in
bonding
• when two or more elements come together and
bond...they form a compound
Oct 14­7:36 AM
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GC Bonding.notebook
October 21, 2011
Covalent Bonding & Compounds:
• two or more nonmetals bonded together
• electrons are shared between the two atoms in
the bond
• Properties of covalent compounds:
low melting and boiling points
usually do not dissolve in water
do not conduct electricity when dissolved in water
Oct 14­7:39 AM
Naming Covalent Compounds...
• name the 1st element with its periodic table name
• change the ending of the 2nd element name to "-ide"
• indicate the # of each atom with a prefix
(mono = 1, di = 2, tri = 3, etc...)
• the prefix "mono" (1) is optional for the 1st element and required for
the 2nd
• if there are two vowels together between the prefix and the element
name - you can drop the element name vowel
Example: triiodide = triodide, monooxide = monoxide
Oct 14­8:56 AM
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GC Bonding.notebook
October 21, 2011
Naming Covalent Compounds:
SF6
C3H8
N2O6
NO
Oct 14­7:44 AM
Writing Covalent Compound Formulas
iodine tribromide
nitrogen trioxide
diphosphorus tetraoxide
carbon tetrafluoride
Oct 14­8:51 AM
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GC Bonding.notebook
October 21, 2011
On pg # 1 in your packet at the bottom...try...
#3 SF6
#4 C3H8
#6 N2O6
sulfur hexafluoride
tricarbon octahydride
dinitrogen hexaoxide
#11 iodine tribromide
#12 nitrogen trioxide
#13 diphosphorus tetraoxide
IBr3
NO3
P2O4
Oct 14­9:01 AM
What are Lewis Structures?
• Show the bonding in a covalent compound in
picture form.
• Bonds are represented by lines, non-bonded
electrons by dots.
• a bond (1 line) = 2 electrons
• From the Lewis Structure you can determine
the shape of the compound, which helps
determine the properties of that compound.
Oct 14­7:52 AM
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GC Bonding.notebook
October 21, 2011
Lewis Dot Structures of Atoms
H
Be
B
C
N
linear
trigonal
tetra-
trigonal
planar
hedral
pyramid
O
F
Ne
# valence e# bonds
shapes
linear
**
bent
linear
Be is a metal, but still can covalently bond
because of its small atomic radius.
It is small enough to have its valence electrons
overlap with another atom's valence electrons.
Oct 14­7:52 AM
Drawing Lewis Structures...The Rules
1. Add up the total # of valence electrons in the formula.
2. Determine the central atom.
the first atom listed (except for hydrogen)
or...
the atom with the least number of valence
electrons (except for hydrogen)
3. Bond all the other atoms to the central atom. Use lines to
represent the bonds. (Remember: each bond = 2 electrons)
Oct 14­7:58 AM
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GC Bonding.notebook
October 21, 2011
The Rules Continued...
4. OCTET RULE: Every atom in the structure must have 8
electrons around it.
Fill in the octets using PAIRS of electrons (dots).
Exceptions: Hydrogen (H) - 2 electrons or 1 bond
Beryllium (Be) - 4 electrons or 2 bonds
Boron (B) - 6 electrons or 3 bonds
5. Check:
total # electrons in picture = # valence electrons counted
Oct 14­8:02 AM
The Rules Continued...
6. CARBON - MUST HAVE 4 bonds, no dots!!!
7. DO NOT string oxygens together O
8. DO NOT make boxes C
C
C
C
O
O...
Oct 15­7:37 AM
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GC Bonding.notebook
October 21, 2011
Single Bond Examples:
1. Cl2
valence e-:
shape:
2. SiF4
valence e-:
shape:
Oct 15­7:32 AM
3. H2O
4. OH-1
valence e-:
shape:
valence e-:
shape:
Oct 15­7:34 AM
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GC Bonding.notebook
5. NH3
valence e-:
shape:
October 21, 2011
6. N2H4
valence e-:
Oct 15­7:35 AM
7. C3H8
valence e-:
8. C2H5OH
valence e-:
Oct 15­7:36 AM
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GC Bonding.notebook
October 21, 2011
Double & Triple Bonds
1. O2
2. N2
Oct 18­8:53 AM
3. C2I4
4. C2H5O
Oct 18­8:53 AM
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GC Bonding.notebook
October 21, 2011
Lewis Structures for Ions
Positive Ions: subtract the # of electrons in the
charge from the total
Negative Ions: add the # of electrons in the charge
to the total
PO4-3
Oct 15­7:45 AM
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