Warm Up
• Name the following compound1.Cl02
• Give the following formula2. Disilicon Hexafluoride3. Carbon tetrachloride
What are the atoms trying to achieve?
Octet rule = atoms want 8 electrons in their valence shell
Exception #1:Hydrogen and Helium only want 2
Covalent Bonding in H2
Covalent Bonding in H2
HH .. HH..
Two hydrogen atoms, each with 1 electron,Two hydrogen atoms, each with 1 electron,
can share those electrons in a covalent bond.can share those electrons in a covalent bond.
HH :: HH
• Sharing the electron pair gives each hydrogen an electron configuration analogous to helium.
Covalent Bonding in F2
Covalent Bonding in F2
Two fluorine atoms, each with 7 valence electrons,Two fluorine atoms, each with 7 valence electrons,
can share those electrons in a covalent bond.can share those electrons in a covalent bond.
• Sharing the electron pair gives each fluorine an electron configuration analogous to neon.
....
....FF.. FF..:: ::
....
....
FF :: FF:: ::........
....
....
ExampleExampleExampleExample
CC ........
FF::..........
Combine carbon (4 valence electrons) andCombine carbon (4 valence electrons) andfour fluorines (7 valence electrons each)four fluorines (7 valence electrons each)
to write a Lewis structure for CFto write a Lewis structure for CF44..
:: FF::........CC
:: FF::........
:: FF::........:: FF::
....
....
The octet rule is satisfied for carbon and The octet rule is satisfied for carbon and each fluorine.each fluorine.
ExampleExampleExampleExample
It is common practice to represent a covalentIt is common practice to represent a covalentbond by a line. We can rewritebond by a line. We can rewrite
:: FF::........CC
:: FF::........
:: FF::........:: FF::
....
....
....
CCFF
FF
FF
FF
....
............:: ::
:: ::
:: ::
....
asas
So… 2 shared electrons can be rewritten as a single line.The line is called a ‘single bond’.
TRY IT!!1.Draw the lewis dot structure for Phosphorus Triiodide2.Draw it again, this time replacing pairs of shared electrons with a single line.
Double bonds• Some atoms share more than 2 pairs of
electrons between them. • You still replace each pair of shared electrons
with a line but if two lines are present between 2 atoms, it is called a DOUBLE BOND.
CC:: :: ::OO....::OO
....:: ::
Carbon dioxideCarbon dioxide
Try drawing the double bonds for carbon dioxide
REMEMBER…
• The atoms want to have 8 valence electrons!• Shared electron pairs can be represented by a
line, which shows that the atoms are bonded.
Let’s
practice!
EthyleneEthylene
AcetyleneAcetylene:: :: ::CC::CC::HH HH
CC:: ::CC....
HH ::::....
HHHHHH
Replace the electron pairs by drawing in the bonds