 Intro to Chemistry Chapter 1, section 3 and Chapter 2, and 2 formulas from Chapter 3 A Preview of Coming Attractions

 ONLY INTENDED FOR MATURE STUDENTS! RIGOROUS

Graffiti Wall  Graffiti wall  Keep it clean and school appropriate.  Write whatever you like on the orange wall.  Maybe it will end up being cool.

Taking notes... CUES 1-2 words CUES Main part for Notes.. Use bullet points... Abbreviate.. Draw pictures to. help you... You do not have. to write in. complete. sentences. Main Part for Notes

化学  Chemistry in Japanese  Literally means “change study.”  Chemistry is the study of matter: the composition of matter and the changes matter undergoes.  Did you start taking notes yet?

Chemistry is not relevant to my life. Am I ever going to use THIS? How should I know? But since Chemistry is all around you, I’m going to guess YES. Do you like to cook? Do you want a pool?

The Scientific Method Chapter 1.3  Observation  Use your senses to make observations and suggest questions.  Hypothesis  A testable “educated guess.”  Experiment  Supports and proves your hypothesis (or doesn’t support and disproves)

The Scientific Method  Analysis of Data  Analyze data collected during the experiment.  Conclusion  What happened?  Was your hypothesis supported or not (try NOT to think of it as success vs failure)?  How could you improve your experiment?  How could you expand upon your original experiment?

Scientific Theory  Theory  A detailed explanation explaining why an experiment works the way it does.  A theory can never be PROVEN completely true.  A theory can always be disproved if new data doesn’t support the theory.  If that happens, theory needs to be revised or discarded.

Scientific Theory  Theory  It doesn’t matter how many scientists believe it. Believing it is true doesn’t make it so.  Consensus isn’t science. The only thing that matters is if the scientific data supports the theory.

Scientific Law  Law  A law is a statement of fact, usually concerning a natural phenomenon.  It doesn’t explain how or why.  Theories explain. Laws don’t explain. They just tell you what it is.  Lets talk about an important law:

The Law of Conservation of Mass  In any chemical reaction or physical change, matter can neither be created nor destroyed.  The amount of matter (mass) doesn’t change.  However, the identity of the matter (what type of substance it is) could change.  mass of the reactancts = mass of the products

Chapter 2  Back to matter…  Matter can be broken down into substances and mixtures.  Substances are pure.  Elements (smallest part of an element is an atom)  Compounds (smallest part of a compound is a molecule)

Substances vs mixtures  Carbon is a substance.  Water is a substance.  Air is a mixture of substances (O 2, N 2, CO 2, etc)

Substances vs mixtures?  You try some  Methane (natural gas)  Coffee  Copper  Salt  Dirt  Sand

Substances: Elements  Elements are on the Periodic Table.  118 elements exist  90 occur naturally (1-92 except for 43 Tc and 61 Pm)  Elements 93 and higher are man made (most of them by Dr. Glenn Seaborg)

Substances: Compounds  Compounds are pure substances too. Common compounds are:  Salt (sodium chloride)  Sugar (sucrose)  Baking Soda (sodium bicarbonate)  Sand (silicon dioxide)  Rubbing Alcohol (isopropanol)  Carbon dioxide

Ionic Compounds vs Molecular Compounds  There are 2 types of compounds  Ionic compounds have ionic bonds and are composed of positive and negative ions.  Ions are formed when atoms lose or gain electrons.  Molecular compounds have covalent bonds.  Electrons are shared between atoms. There are no ions or charges.

Substances: Elements and Compounds  How do you tell if it’s an element or a compound?  An element cannot be broken down into anything simpler.  A compound can be separated into smaller elements. You must use a chemical reaction to break down a compound.

Compound vs Mixture  How do you tell if it’s an compound or a mixture?  A compound is bonded together. You must use a chemical reaction to break down a compound into elements.  A mixture isn’t bonded together. The substances are just mixed together. A mixture may be separated by physical separation techniques.

What are physical separation techniques?  Evaporation—can separate DISSOLVED solids from the liquid.  Filtration—can separate UNDISSOLVED solids from the liquid.  Decanting—can separate a dense undissolved solid from the liquid (because the solid is on the bottom and so you can pour off the liquid).

A physical separation technique sometimes tested on the SOL.  Chromatography  Can be used to separate a mixture of solids dissolved in a liquid.  Ink  Natural dyes

Homework  HW: research chromatography online. Type a 3 paragraph essay (5 for Adv Chem) on chromatography. MLA Format.  Cite your sources (need 3, none of which may be Wikipedia; however, Wikipedia is a great place to start and learn about the topic).  Schwartz Definition of Paragraph = 5 well constructed sentences which all relate to the same main idea.

Chemical Reactions  Reactants  Products  You can have 1 or more reactants  You will produce 1 or more products  How many you need and how much you produce is characteristic of the specific reaction.  We will study 5 major types of reactions starting in Chapter 8.  Chemical reactions are PERMANENT and NOT reversible.

Physical Properties  Matter has both physical and chemical properties.  Physical properties can be observed without CHANGING the type of matter.  When solid water (ice) melts it becomes liquid water. A change of state is a physical change ( Δ or delta means change).  Physical changes are NOT permanent and are reversible.

Chemical Properties  Chemical properties can be ONLY be observed BY CHANGING the type of matter.  When salt (NaCl) is dissolved in water, a solution is formed. That is a physical change. The salt is still salt and the water is still water. You can separate them easily by evaporating the water.

Chemical Properties  But when sodium oxide (Na 2 O) is dissolved in water a solution is formed at first, but then a chemical reaction occurs. That is a chemical change. Sodium oxide reacts with water to form sodium hydroxide (NaOH). If you evaporate the water, you will have solid NaOH not Na 2 O.  We write that reaction as Na 2 O + H 2 O  2 NaOH

Why does one react and the other doesn’t?  Well, that’s chemistry. It’s not all that complicated but the answer won’t make much sense right now.  But, by the end of the course (Jan or June) it will make a lot of sense.

NOW: STUDY HARD!! minutes every night! After you do all your reading and homework, etc. If you do, you won’t end up looking like this poor kitty the night before the test. You should plan on studying hours for EVERY chemistry test. But it doesn’t all have to be done the night before.

What’s in it for YOU? Well, studies show that if you review something LATER THAT SAME DAY (and that’s called studying), you have an 80% better chance of actually remembering it. Start Time End Time

Helpful Hints  Take this class one step at a time.  Read and outline the chapter. If you haven’t already started doing Chapter 3, you are already BEHIND! Don’t just copy what the book says into your notes. Rewrite it in your words, so you understand what you wrote.  Know the VOCAB from the book. If you don’t understand the words, you won’t know what I am talking about.

Chemistry Builds on Itself  If you don’t understand what we are doing today, you aren’t going to get it tomorrow, because what we learn tomorrow will depend on what we learned today.  You can’t do Chapter 19 until you’ve learned  Google if you don’t understand something! Ask questions!  Work with each other! Form study groups!!

It takes Time, and Work and EFFORT!  It took over 250 years of hard work by thousands of brilliant scientists to “figure out” Chemistry!  How are you going to learn it in 5 minutes or once a week?

Chemistry (or Schwartz) is too Hard or There’s Math in Chemistry!  It’s not.  I’m not. But I can be if you don’t do your job.  Yeah, there is. Algebra 1. Lots of it.  Sometimes, this will seem like your second math class.  Let’s do some math! This puzzle is UNSOLVABLE, but Chemistry is SOLVABLE, if you work.

Density  Anyone remember the formula for density?  Anyone remember the “density heart?”

d = m / V OMG, we just zoomed into Chapter 3  Density equals mass divided by volume. That’s what the formula is telling you. (Most of you probably already knew that).  Density has units of “g/mL” or “g/cm 3 ”  Mass has units of grams (g).  Volume has units of milliliters (1 mL = 1cm 3 )  But what does density really mean? Density tells you how much 1 milliliter (volume) is going to weigh.  One mL of water weighs 1 g. One mL of gold weighs 19.3 g. Write this down and learn it!

d = m / V  If you know 2 of those 3 variables, you can solve for (calculate) the remaining one. This is basic, basic algebra 1.  Rearrange the formula so that mass is by itself.  Rearrange the formula so that volume is by itself.

d = m / V  If you know 2 of those 3 variables, you can solve for (calculate) the remaining one. This is basic, basic algebra 1.  Rearrange the formula so that mass is by itself.  Rearrange the formula so that volume is by itself. m = V x d

d = m / V  If you know 2 of those 3 variables, you can solve for (calculate) the remaining one. This is basic, basic algebra 1.  Rearrange the formula so that mass is by itself.  Rearrange the formula so that volume is by itself. m = V x d V = m / d

d = m / V  If you know 2 of those 3 variables, you can solve for (calculate) the remaining one. This is basic, basic algebra 1.  Rearrange the formula so that mass is by itself.  Rearrange the formula so that volume is by itself.  Write these into your notes. m = V x d V = m / d

d = m / V  If you know 2 of those 3 variables, you can solve for (calculate) the remaining one. This is basic, basic algebra 1.  Rearrange the formula so that mass is by itself.  Rearrange the formula so that volume is by itself.  You don’t need to memorize all 3. Memorize the top one and rearrange when you need one of the others! m = V x d V = m / d

K = °C  This formula converts Celcius temperature into Kelvin temperature.  This will be on the SOL.  For some problems in Chemistry, we need to use Kelvin temperature.  We don’t use Fahrenheit temp. If this is first semester, it’s probably about 80°F outside (maybe 30°F it is second semester). But you do need to know how to convert from Celcius to Kelvin (and vice versa).  What is the formula if you want °C by itself?

K = °C  This formula converts Celcius temperature into Kelvin temperature.  This will be on the SOL.  For some problems in Chemistry, we need to use Kelvin temperature.  We don’t use Fahrenheit temp. If this is first semester, it’s probably about 80°F outside (maybe 30°F it is second semester). But you do need to know how to convert from Celcius to Kelvin (and vice versa).  Answer: °C = K − 273

Remember… What you actually learned today is… What you have left after you forgot all the other stuff I told you. Learning requires real effort on your part. Some kids think “learning” means “teaching yourself.” They are right. I can’t MAKE you learn. But, I am here to help you learn!

The End