Amazing Bending Water!
Justify
•What caused the water to bend?
Covalent Bonds can be polar or
nonpolar
•Nonpolar Covalent Bond – Electrons
shared equally between the atoms
•Polar Covalent Bond – Electrons shared
unequally due to difference in
electronegativity
•Electrons reside closest to the atom that is
most electronegative
H
F
Because fluorine is drastically more
electronegative, it holds electrons closer to
itself when in a covalent bond with
hydrogen.
δ+
δ-
H F
Hydrogen is given a partial positive charge
and fluorine is given a partial negative charge
because it’s more electronegative.
Class Example
•Label the location of the partial
positive and partial negative charges in
OH
Elbow Partner Talk
Label the location of the partial
positive and partial negative
charges in water.
Dipole Moments
•Polar compound leads to the
concentration of charge at the poles of
the element.
•This is known as a dipole moment
Exit Ticket
Indicate the dipole moment (if any)
for all molecules below after your
drawing is complete
1. Draw the Lewis structure for H2O
2. Draw the Lewis structure for NH3
3. Draw the Lewis structure for HCN
Drawing Lewis Dot Structures
Not easy, don’t give up, keep trying
1. Connect elements using a line. C is always in the
middle. Nitrogen is usually in the middle. H
always on the outside.
2. Count all the valence e-s for the entire
compound. Add them all up. Those are the # of
electrons available! (Add electrons if anion,
subtract electrons if cation)
3. Subtract that number from the # of electrons
already used when you drew the lines.
Drawing Lewis Dot Structures
Not easy, don’t give up, keep trying
4. The remaining electrons are placed in pairs around
the compound.
5. Make sure all elements are stable (octet rule). H
needs 2. All others need 8. (Remember each line
represents 2 bonding electrons)
6. If atoms are not stable (you used too many electrons
that are not available) then erase a lone pair from that
atom and draw a double bond on that atom If that
doesn’t work then a triple bond may be needed. Use
trial and error until all atoms follow the octet rule and
the total number of electrons equals that of the
Hover Cam
• 5 Examples are demonstrated using
HoverCam
• 20 pratice examples are for students to
use to master the process of drawing
lewis structures for compounds.