Covalent Bonding
• In ionic bonding, electrons were transferred to
other atoms.
• In covalent bonding, electrons are shared
between atoms.
• We represent covalent compounds with
electron dot diagrams. (Another short cut!)
• The number of dots around an atom is the
same as the number of valence electrons.
(The same as the group number)
• Ex.
Steps in Electron Dot Diagrams (EDD for short)
Example A. Hydrogen forms a covalent bond
with another hydrogen atom to form a hydrogen
molecule H2
1. Figure out how many atoms of each element
you need. Draw the electron dot diagram for
each of the atoms separately.
2. Decide how many electrons each atom wants
to GAIN to have a full outer energy level!
(usually occurs between nonmetals who want to
gain electrons).
Each H atom wants
to gain 1 to have a
full outer energy
level!
3. Line up the electrons to get ready to share.
4. For each two electrons that will be shared,
replace the dots with a bond (a line). Continue
until each is atom “happy” when you count
shared and any remaining valence electrons.
Example B.
• Hydrogen and oxygen bond covalently to form
a water molecule: H20
1) Figure out how many atoms of each element you
need. Draw the electron dot diagram for each of the
atoms separately.
2. Decide how many electrons each atom wants
to GAIN to have a full outer energy level!
(usually occurs between nonmetals who want to
gain electrons).
- Each H wants to gain 1
- O wants to gain 2
3. Line up the electrons to get ready to share.
4. For each two electrons that will be shared,
replace the dots with a bond (a line). Continue
until each is atom “happy” when you count
shared and any remaining valence electrons.
Example C
• Two molecules of oxygen bond covalently to
form an oxygen molecule O2
1) Figure out how many atoms of each element
you need. Draw the electron dot diagram for
each of the atoms separately.
2. Decide how many electrons each atom wants
to GAIN to have a full outer energy level!
(usually occurs between nonmetals who want to
gain electrons).
- Each O
wants to gain 2
electrons
3. Line up the electrons to get ready to share.
4. For each two electrons that will be shared,
replace the dots with a bond (a line). Continue
until each is atom “happy” when you count
shared and any remaining valence electrons.
Example D
Carbon and Oxygen bond covalently to form carbon dioxide: CO2
1) Figure out how many atoms of each element you need.
Draw the electron dot diagram for each of the atoms
separately.
2. Decide how many electrons each atom wants
to GAIN to have a full outer energy level!
Each O wants to
gain 2
C wants to gain 4
3. Line up the electrons to get ready to share.
4. For each two electrons that will be shared,
replace the dots with a bond (a line). Continue
until each is atom “happy” when you count
shared and any remaining valence electrons.
• SKIP Practice EDDs #1-6
• Do the WS “Covalent Bonding Practice #2”
• Check with key at the Kiosk