•Deduce the Lewis structures of molecules and ions for up to four
electrons pairs on each atom
•Predict the shape and bond angles for species with four, three and two
negative charge centers on the center atom using the valence shell
electron pair repulsion theory (VSEPR)
•Analyze the physical properties of covalent compounds resulting from
single, double and triple bonds
•Describe and compare the structure and bonding in the three
allotropes of carbon; diamond, graphite and fullerene.
•Describe the structure and bonding of silicon and silicon dioxide
DIATOMIC MOLECULES
W/ SINGLE BONDS
DIATOMIC MOLECULES
W/ DOUBLE BONDS
DIATOMIC MOLECULES
W/ TRIPLE BONDS
:
:O= C= O:
:
CARBON DIOXIDE
TWO DOUBLE BONDS
H
O:
H
WATER
CARBON MONOXIDE
TRIPLE BOND
POLYATOMIC IONS
A group of atoms covalently bonded with a charge that
form ionic bonds w/ oppositely charged ions
CARBONATE CO32AMMONIUM
NH4+
HYDROGEN CARBONATE CO32-
HYDROXIDE OHSULFATE SO4 2PHOSPHATE PO4 3NITRATE NO3 -
LOOK AT THE FOLLOWING YOU TUBE VIDEOS FOR STEP
BY STEP INSTRUCTIONS ON DRAWING LEWIS
STRUCTURES
BASIC STEPS TO DRAW LEWIS STRUCTURES
http://www.youtube.com/watch?v=PtMifU1py5I
POLYATOMIC ION LEWIS STRUCTURES
http://www.youtube.com/watch?v=FrICbMseyhs
Predict the shape and bond angles for species with four,
three and two negative charge centers on the center atom
using the valence shell electron pair repulsion theory
(VSEPR)
http://www.youtube.com/watch?v=sceYMpBrNNo&safe=active
http://www.youtube.com/watch?v=xwgid9YuH58
http://www.youtube.com/watch?v=qvPKWcXdo7Y
Analyze the physical properties of covalent compounds
resulting from single, double and triple bonds
DUE TO THE FACT THAT TRIPLE BONDS ARE
THE STRONGEST AND SINGLE BONDS ARE THE
WEAKEST, IT STANDS TO REASON THAT A
MOLECULE WITH A TRIPLE BOND WILL HAVE
A MUCH HIGHER MELTING AND BOILING
POINT THAN A DOUBLE AND EVEN MORE
THAN A MOLECULE WITH A SINGL BOND
Describe and compare the structure and bonding in the
three allotropes of carbon; diamond, graphite and
fullerene.
DIAMONDS
-hardest substance known
to man
-brittle (not malleable)
-insulator (non-conductor)
-insoluble in water
-very high melting point
GRAPHITE
-soft and slippery
-brittle
-electrical conductor
-insoluble in water
-very high melting point
WATCH THE TUTORIAL BELOW FOR MORE INFORMATION
FULLERENES
http://www.youtube.com/watch?v=sUqr6Uk29Z8&safe=active
-soft, slippery and brittle
-semi-insulator (conductivity falls between that of graphite and diamond)
-Insoluble in water
-low melting point solids
•Describe the structure and bonding of silicon and silicon
dioxide
The structure of silicon dioxide, SiO2
Silicon dioxide is also known as silicon(IV) oxide.
The giant covalent structure of silicon dioxide
There are three different crystal forms of silicon dioxide. The easiest one
to remember and draw is based on the diamond structure.
Crystalline silicon has the same structure as diamond. To turn it into
silicon dioxide, all you need to do is to modify the silicon structure by
including some oxygen atoms.
Notice that each silicon atom is bridged to its neighbours by an oxygen
atom. Don't forget that this is just a tiny part of a giant structure extending
on all 3 dimensions.
The physical properties of silicon dioxide
Silicon dioxide
•has a high melting point - varying depending on what the particular
structure is (remember that the structure given is only one of three
possible structures), but around 1700°C. Very strong silicon-oxygen
covalent bonds have to be broken throughout the structure before melting
occurs.
•is hard. This is due to the need to break the very strong covalent bonds.
•doesn't conduct electricity. There aren't any delocalized electrons. All the
electrons are held tightly between the atoms, and aren't free to move.
•is insoluble in water and organic solvents. There are no possible
attractions which could occur between solvent molecules and the silicon
or oxygen atoms which could overcome the covalent bonds in the giant
structure.
http://www.youtube.com/watch?v=PiYnQLI-ufU&safe=active