We talked about the Law of
Conservation of mass and how matter cannot be created or destroyed. If
you burn a log, the mass of all the ashes, smoke, gases, and everything
that is burned off and left behind EQUALS the mass of the original log.
students discussed physical vs. chemical properties and changes.
They've heard all of this before I am sure, but it doesn't hurt to go
over it again. Then we did a challenge to see if they really knew their
Need to practice identifying chemical and physical properties? Check this out!
Need help identifying types of matter and whether they are heterogeneous or homogeneous? Check this out!
is a chemistry word for disorder. An increase in entropy is
spontaneous. By looking for four things in a reaction, students can
determine whether a reaction is spontaneous or nonspontaneous by looking
for an increase in entropy. Exothermic reactions are spontaneous and show an increase in entropy. Gases are messier than solids, so a reaction that forms a gas shows an increase in entropy. More
molecules show an increase in entropy. Count the coefficients on either
side of a balanced equation. If the products have more molecules then
there is an increase in entropy and the reaction could be spontaneous.
A decrease in the size of molecules (count atoms making up the molecule) is an increase in entropy. Students
look for all four things and decide whether the overall reaction would
lead to an increase in entropy and be spontaneous.
Students learned about reaction rates and how to increase them. They
also learned about reversible reactions and how Le Chatlier's principle
influences shifts of equilibrium in reversible reactions.
as you apply a stress to a system, the system will shift in response to
the stress. If you add one of the molecules it will shift away from
that molecule. If you take away a molecule, it will shift towards it to
make more. Heat works the same way.
is the tricky one. If pressure is applied to an equilibrium, then the
reaction will shift to the side that has the least amount of molecules
(count the coefficients).
started by talking about the simple definition of the terms, what the
probably products and reactants are and went over a basic formula for
the reaction types the students need to be familiar with.
Reaction Types include:
discussing the basics, we drew cartoons of stick men and women going on
dates to show how atoms move around in the simpler reactions. The
picture posted is someone else's version of single replacement (see the
one guy switches with the other). For more help with this, check here.
are learning to balance equations. Today they learned that reactants
are what you start with and are on the left side of the equation.
Products are on the right side of the arrow and are what is made by
process of a chemical change.
Because of the Law of
Conservation of Mass, the number of atoms have to be equal on both
sides. To balance an equation, the coefficients are changed.
Coefficients are the big numbers in front that tell you how many
molecules there are. The subscripts (the little lower numbers) are not
allowed to be changed because those are there to make neutrally bonded
molecules (what we learned in the last unit.
By changing the coefficients and counting the number of atoms on both sides of the arrow, balancing can be achieved.
who has ever had to share something with someone else knows that
sometimes isn't exactly even. Covalent molecules or bonds are no
a molecules is nonpolar covalent, it is sharing its electrons equally.
The best example of this is in diatomic molecules. Diatomic molecules
are two of the same atom bonded together - so they would have exactly
the same pull. Symmetrical molecules are also nonpolar.
covalent bonds occur when electrons are not equally shared. One atom,
usually more electronegative, has a stronger pull on the electrons and
shares them unequally. The other atom that is less electronegative has a
smaller hold on the electrons and is thus can be slightly positive.
One way to remember this is... "Polar Bears do not share... equally."
If you were absent for the Physical versus Chemical lab, you can make up the majority of it by following the link below and watching YouTube videos of the experiments. You can also just check them out because they are cool.
Open a link in a new tab. In the blue box, look for "Play Games" and "Scatter." You will then need to drag the names to the correct formula. If it disappears, you matched it correctly. Play each set a couple of times until you get really good. You can also use these as flashcards and make up and take tests.
Click on the rice above to test your knowledge of the Periodic Table while earning rice for the United Nations World Food Program. You can also test your knowledge of vocabulary as an excellent SAT prep.