Happy
Presidents
Day!
Monday, Feb. 17th: “A” Day
Tuesday, Feb. 18th: “B” Day
Agenda
Finish section 6.1: “Covalent Bonds”
Lab Discussion/Write-up: “Nonmetal Reaction”
Lab: “Non-metal Reaction”
Homework: Pg. 198: #1-14
Completed lab will be due next time…
Polar Molecules Have Positive and
Negative Ends
In a polar covalent bond, the ends of the bond
have opposite partial charges because one of the
atoms is “hogging” the electrons.
Dipole: a molecule or part of a molecule that
contains both positively and negatively charged
regions.
In a polar covalent bond, the shared pair of
electrons are more likely to be found near the
more electronegative atom.
Polar Molecules Have Positive and
Negative Ends
The Greek symbol  (delta) means partial.
  + is used to show a partial positive charge
  – is used to show a partial negative charge
 Example: H+ F– is polar covalent
Because the F atom has a partial negative
charge, the electron pair is more likely to be
found closer to the fluorine atom.
Polarity Is Related to Bond Strength
In general, the greater the electronegativity
difference, the greater the polarity and the
stronger the bond.
Polarity Is Related to Bond Strength
Think of it this way:
You know that ionic bonds are stronger than
covalent bonds.
The greater the difference in electronegativity,
the closer the covalent bond comes to being like
an ionic bond.
Electronegativity and Bond Types
Differences in electronegativity values provide
one model that can tell you which type of bond
two atoms will form.
Another general rule states:
An ionic bond forms between a metal and a
non-metal.
A covalent bond forms between two
non-metals.
Properties of Substances Depend on
Bond Type
The type of bond that forms (metallic, ionic, or
covalent) determines the physical and chemical
properties of the substance.
Metallic bonds: good conductors in solid state
because electrons are free to move around.
Ionic bonds: strong attraction between ions makes
them solids with high melting/boiling points.
Covalent bonds: weaker attraction between
molecules makes them gases/liquids at room
temperature or solids with low melting/boiling
points.
Your lab partner will be…
Lab: “Non-metal Reaction”
Discussion
The active ingredient in household bleach is
sodium hypochlorite, NaClO.
Sodium hypochlorite contains 1 metal atom (Na)
and 2 non-metal atoms (Cl and O).
Oxygen gas supports combustion (burning) while
chlorine gas does not.
In this lab, you will remove the oxygen from
sodium hypochlorite in order to
identify its presence.
Lab: “Non-metal Reaction”
Changes to Materials List
Add the following to your list of materials:
Test tube holder
Test tube rack
Graduated cylinder (50 mL)
Balance
Formula for cobalt(II) chloride, CoCl2
Lab: “Nonmetal Reaction”
Lab Write-Up
Title
Purpose
Hypothesis
Materials
Procedure
We will follow the procedure just as described
Reflection Statement
Remember to update
your table of contents!
Lab: “Nonmetal Reaction”
Discussion
On the back of your lab handout, below question
#4, list 3 observations from the lab.
Instead of using a test tube holder like the picture
shows, you can perform the test while the test
tube is in the rack. This way you won’t have to
hold it.
You and your lab partner need to work together
to make this lab work. The match needs to be
blown out just as your partner takes their thumb
off the end of the test tube. Why?
Lab: “Nonmetal Reaction”
Safety Items
Liquid laundry bleach, containing NaClO, and cobalt
chloride, CoCl2, can both be dangerous. Be careful
when handling them and clean up any spills
immediately.
DO NOT inhale any of the vapors coming out of the
test tube or get too close to the test tube!
DO NOT let the pressure build up in the test tube!
Hair must be tied back because we will be using
matches.
Be sure to wash your hands when you’re done.
Lab: “Nonmetal Reaction”
Lab Questions
Use complete sentences to answer the 2 lab
preview questions on the top of the lab handout
as well as all of the lab conclusion questions.
Have fun and be safe!
Completed lab will be due
next time…
Homework
Finish “Nonmetal Reaction” lab questions in
COMPLETE SENTENCES.
Sec. 6.1 review, pg. 198: #1-14
Sec. 6.1 quiz next time…