Transcript Unit 4: Periodic Trends

After today, you will be able to…
• Write structural formulas and dot
formulas for covalently bonded
molecules
• Identify shared and unshared electrons
• Explain the difference between single,
double, and triple bonds - and write
them using structural formulas/dot
formulas
Unit 4: Chemical Bonding
Covalent Bonding Basics
Covalent Bonding
A sharing of electrons.
• A single covalent bond is made up of
two electrons
• One electron is donated to the bond
from each atom
• Covalent bonding occurs between
nonmetals only
• Atoms that are covalently bonded
are called molecules or molecular
compounds.
Properties of Molecular Compounds
• Covalent bonds are much weaker
than ionic bonds
• Much lower melting and boiling
points
• Is a solid, liquid, or gas at room
temperature
• Non-conductors in any state
Properties of Molecular Compounds
The chemical formula for a covalently
bonded group of atoms is called a
molecular formula.
• Indicates the exact makeup of one
molecule.
• Example: C6H12O6
H
Group Group
14
15
Group
16
Group
17
# of
valence
electrons
1
4
5
6
7
# of
electrons
short
1
4
3
2
1
# of bonds
made
1
4
3
2
1
Example: Write the dot and
structural formula for: H2
Rough Copy (Work):
Dot Formula:
HH
H
H
Lewis Structural Formula:
H
Single bond: A shared
pair of two electrons.
H
Example: Write the dot and
structural formula for: O2
Rough Copy (Work):
Dot Formula:
O O
O
O
Lewis Structural Formula:
O O
Double bond: Two shared
pairs of four electrons.
Unshared pair of
electrons
Example: Write the dot and
structural formula for: N2
Rough Copy (Work):
Dot Formula:
N N
N
N
Lewis Structural Formula:
N
N
Triple bond: Three shared
pairs of six electrons.
Example: Write the dot and
structural formula for: H2O
Rough Copy (Work):
Helpful tip: Put the atom
in the middle that wants
to make the most bonds!
Dot Formula:
OH
H
O
H
H
Lewis Structural Formula:
O H
H
Example: Write the dot and
structural formula for: ONF
Rough Copy (Work):
Dot Formula:
O NF
O
N
F
Lewis Structural Formula:
O N F