Wednesday October 30, 2014

Wednesday October 30, 2014

Chemical Equations and Reactions + Presentations

Today students will present on their molecule.

After everyone has presented we will move onto a new subject, chemical reactions and equations with a side dish of the Law of Conservation of Mass.

Chemical reactions are a vital part of chemistry. Chemical reactions are the fun part where things have the possibility to blow up! They are also the everyday part that we experience when we extract coffee from coffee beans, eat our meals and generally interact with the world. Chemical reactions are taking place inside your body by the thousands as you read this!

Chemical reactions take place everywhere and anywhere. One or more things react with one or more other things and suddenly you have more of less things than you started with.

Chemical equations are how we visualize and ‘figure out’ reactions. They help us understand and predict how a reaction will react. They also tell us what kind of chemical reaction has or will take place.

In industry, we need to know how chemical equations balance, so we can combine the correct amount of ingredients.

Chemical reactions often result in surprising results!  Consider combining Sodium (Na), a highly poisonous and reactive metal, with Chlorine (Cl), a deadly gas.  After combining them we NaCl, Sodium chloride, ordinary table salt!  And, of course, chemical reactions can have the opposite effect, combining harmless ingredients to make explosives, for example.

In order to understand chemistry, and how molecules and elements combine, we need to learn about chemical equations.

You probably already know that, in most cases, matter can not be created or destroyed.  It just changes form, from one thing to another.

When you burn wood, your combine the wood (cellulose molecules) with oxygen to create carbon dioxide and water.  You have the same amounts of matter before and after, although, of course, most of it goes out the chimney.  What is left is unburned carbon, along with trace minerals.

So, the key thing to remember about chemical equations is that, if properly balanced, they will always have the same numbers of each element on each side of the equation.  Of course, that is no different than a mathematical equation, where the two sides have to balance.

For example,

CO2 + H2O <> H2CO3

is a proper equation.  You have one carbon atom on each side, two hydrogens, and three oxygens.  This is the equation for carbonated water, where carbon dioxide combines with water to form carbonic acid (a weak acid).  Have you ever heard that you can use Coca Cola to loosen nuts and bolts that are rusted?  That is true, and it is because of the carbonic acid in Coca Cola (or any other soda pop).

You may have noticed that the equation has “<>” instead of “=”  That means it is a reversible reaction.  When they pump in carbon dioxide in the soda factory, they create carbonic acid.  When you open the bottle or can, and it fizzes, it is because the reaction goes back the other way, releasing carbon dioxide and tickling your nose.

So, here is another example:

NaOH + HCl = NaCl + H2O

Is it balanced?  Yes it is!  Make sure you convince yourself that it has the same numbers of each element on each side!

Let’s try another”

NaOH + H2S = NaS + H2O

Well, it has one NA and one S on each side.  And it has one O on each side.  But one side has three H, and the other side only has 2 H.

Nope!  Not balanced!

So, how do we fix that??  Well, that is where “valence electrons” and “Valence” or “Charge” comes in.

We can tell from the periodic table, or from the first equation, that Na has a charge of +1.  And we also know that H as a charge of +1.  Now, O has a charge of -2.  That means that OH has a total charge of -1.  Now S is in the same column as O, and it has a charge of -2.  You can also tell that from the formula H2S, where two H are needed to balance the S.

That should tell you that you will need two Na to replace the two H, to make Na2S.  How do you get two Na?  Easy!  Use two NaOH

Now the equation becomes:

2(NaOH) + H2S = Na2S + H2O

Oops!  Now we do not balance again!

So, let’s add up each element on each side.

On the left hand side, we have:

2 Na

1 S

2 H (from the two OH) plus 2 H from the H2S = 4 H

2 O from the two OH

So, if we change it to:

2(NaOH) + H2S = Na2S + 2(H2O), does it now balance?  Yes it does!  Please convince yourself of that.

Now no matter how complex a chemical equation becomes, you can always solve it, if you know the things that go into the reaction, and the things that come out!

Monday October 20, 2014

Monday October 20, 2014

Today we have Lab!!!!! I know you are truly thrilled about the prospect of playing with chemicals and generally having an interesting time. (And hopefully fun without being too dangerous!)

Today we are exploring the relative bond strength of different molecules. We will be melting, or attempting to melt several different molecules. Those that melt (state change) have weaker bonds. The molecules that do not melt have stronger bonds. Based on the relative strength we will be able to determine if the bond is ionic or covalent!

Friday October 17, 2014

Friday October 17, 2014

Today was a good day! In class we talked about bonds, what they are and the different types. If you missed class (and there were only 3 of you not in class!!!!) please read the below:

Bonds

The name is Bond…. Chemical bond.  I am the glue that holds it all together.  Remember that fancy martini glass James Bond used?  Held together by chemical bonds!  Same with his Walther P38.  Same with James, himself.  And, come to think of it, I also hold the villain together.  Pretty powerful stuff!

Remember when we talked about molecules? Well molecules are half atoms and half bonds. Bonds tell us how atoms fit together. They tell us how strongly or loosely molecules are held together.

So, really, “bonds” are about electrons.  You may have already figured out that chemistry is actually mostly about electrons!  They are the smallest of the three particles in the atom (what are the others ones, again?) and they weigh very little.

But they fly around at almost the speed of light, and they are constantly in motion.

So, the atoms that make up molecules can either share electrons, or they can keep them to themselves.

In table salt (NaCl, remember?) the Sodium loses its electron and the Chlorine captures it.  So, now the extra electron is bound or bonded to the chlorine atom.

Of course, in other molecules, the atoms share electrons.

If they are shared, that is a covalent bond.  Think of that prefix, “co”.  Like coexist (meaning getting along together) or cooperate.  In a covalent bond, the atoms share, or cooperate or coexist (you get the idea!) their electrons.

Because they share the electrons, molecules with covalent bonds tend to be strong.  Neither atom wants to give up those shared electrons, so the atoms stick together.  That makes a strong bond, kind of like the loyalty James showed to Q, his boss.

Ionic bonds can also be strong, but can be broken apart, often by water, to form solutions.  You all know how easily table salt dissolves in water.  And, by tasting it, you know that it is salt water.  The salt has not changed its properties, it has just broken apart into sodium ions and chloride ions.  Since they do not care to share electrons, that is easy for them to do.  They say that breaking up is hard to do, but not so much if you are ionic. You can only find ionic bonds between a metal and a non-metal

Metallic bonds are just a little different. They share electrons freely, no single atom having more electrons than another. Metallic bonds are one reason that metal conducts electricity so well. The electrons freely flow through the metal.

Dipole-Dipole is just fun to say! Now say it like Bond, James Bond. Dipole-dipole bonds are weak and variable. The positive end of one molecule will bond weakly with the negative end of another molecule. The bonds break and reform easily when molecules are in solution (liquid).

Hydrogen bonds are really awesome. They are really weak bonds that disappear and reform in the blink of an eye. There are tons of them in Bonds martini’s. They only form between water molecules. Hydrogen bonds are like dipole-dipole bonds, they form between the positive and negative poles of water molecules. So, between the oxygen of one molecule and a hydrogen of another molecule hydrogen bonds can form.

Covalent bonds are some of the most common bonds. In covalent molecules the atoms share valence electrons equally. So, if an electron is shared between two carbon atoms it will spend half of its time with one carbon atom and the other half of the time with the other carbon atom. Covalent bonds are between non-metal atoms.

Thursday October 16, 2014

Thursday October 16, 2014

Today we will review the gumdrop activity we did yesterday.

Today we are going to be drawing molecules. I have a worksheet of molecules that we will be drawing in your notebook for credit. Drawing molecules will help you understand how atoms fit together. It will really help you when we start building chemical equations (which have the fun chemical labs!). You need to understand how atoms fit together to understand which atoms can go with which other atoms.

As a note: next week we have NWEA's. I plan on us doing fun labs after the test next week to give everyone a mental break and a chance to relax a little.

Wednesday October 15, 2014

Wednesday October 15, 2014

Today we will finally be learning about molecules! We will be learning about how atoms fit together to make molecules. We will be building molecules with tooth picks and gum drops. In this class you will get a visual understanding of what molecules are and how they work. You will experience the multidimensional of molecules.

If you are not here today read the below paper I wrote up for you. Also look up and do a little research on molecules. As a final part look up the angle of bonds. Atoms do not just bunch together randomly, they fit together in particular orders. New atoms join molecules as far away from other atoms as they can get.

Molecules:

Everything in the universe is made up of either atoms or empty space.   But, atoms alone would be pretty boring, and not very useful.  The cool thing is that atoms combine to make molecules!  And molecules make up just about everything.  The rocks and trees, cats and bird, and even you are made up of molecules.

Now, atoms do not just combine any old way.  They follow rules as to how they combine.  And some do not combine at all, unless they are forced!

That is really what chemistry is all about, learning how and why atoms combine the way that they do.

Atoms have valence electrons (don’t worry about what that means, just go with the flow for now) that combine with the electrons from other atoms, and that is how molecules are formed.  Almost always, atoms are “happiest” if they have eight electrons in their outermost shell (eight valence electrons).  Or, the atoms are also satisfied if they have no valence electrons.  So, atoms like to combine with other atoms so that they wind up with those eight electrons.

For example. Oxygen has six valence electrons.  Hydrogen has one valence electron.  So, one oxygen tends to combine with two hydrogens.  That way, the oxygen gets two more electrons (to make eight!), and the hydrogens each give up their only electron, so they have none.  Confusing?  Yes, it is.  It took scientist a long time to figure that out.

To try another example. Sodium (Na) has one electron in its outermost shell (one valence electron), while Chlorine (CL) has seven.  So, one sodium combines with one chlorine to make NaCl (ordinary table salt).  The chlorine now has eight electrons, and sodium has none, and they are stable.  Sodium is a shiny metal.  If you put it in your hand, it would eat right through your skin to the bone!  Chlorine is a very, very deadly gas.  But, when you put them together, they make table salt.  And guess what?  We need salt to live (of course, too much is bad, but we have to have it to survive).

We can look at the periodic table to help us figure out how many valence electrons each element has.  Those in the first column have one valence electron.  Those in the seventh column have seven valence electrons (see that Chlorine is in that column).

Notice that the elements with four or less valence electrons want to give them up, while those with more than four want to get them.  And then they are both happy.

A molecule is two or more atoms joined together. The molecule can share characteristics of the element or have totally new characteristics. Oxygen is a life sustaining element. We breath in O2, and essential component in our bodies, and we breathe out CO2, a deadly molecule. Our lungs transfer the oxygen into our red blood cells which transfer it throughout our body. Our lungs release the CO2 as waste. Breathing in CO2 at too high of a concentration will cause coma and eventually death. O2 and CO2 are very similar molecules that have drastically different results in the human body.

Other than the fact that your entire body is made of molecules why are they important? Well, their atomic composition tells us a lot about how molecules work in our body, and their uses. Ethanol and methanol are two very similar molecules. The chemical formula for ethanol is CH3CH2OH and the chemical formula for methanol is CH3OH. Ethanol is grain alcohol, a form of alcohol that is commonly enjoyed by the over 21 crowd. Methanol is wood alcohol, which is deadly for humans. (In the human body it breaks down into formic acid which can cause blindness, coma and eventually death.)

The difference between ethanol and methanol isn’t just the name, it is the extra CH2, group. The simple addition of one carbon and two hydrogens allows the human body to digest ethanol. It changes a poison into something edible.

As you can see from this, molecules can be very, very complicated.  Proteins and carbohydrates can have thousands and thousands of atoms.

But, we will stick with the simpler molecules in this class.  That is ok, because the simpler molecules are really just as interesting!  When atoms combine, they can really change properties a great deal.  Table salt is one example, with a toxic gas and a toxic metal combining to make something that is crucial for good popcorn!

Your bones, for example, are mostly made up of calcium.  But it is not just pure calcium.  In must be Calcium oxide, or calcium carbonate or one of many other combinations.

You may have noticed that the names of compounds follow a pattern.  In general, especially for the molecules we will study, the names start with the electron donor (the atom or element that gives up its electrons, and is over on the left side of the periodic table)  Then, the electron “grabber” is named.  So, we have Sodium Chloride.  Or Calcium Oxide.  How about water?  Why is that not called Hydrogen oxide???  Just because it is so common.  But, you would certainly be correct in calling it that!

And, notice that the second part of the name is changed just a little bit.  Chlorine becomes chloride, meaning it is an ion (another new word!).  An ion is just an atom without the normal number of electrons, so that one is easy!  The sodium in sodium chloride is also an ion.

Thur Oct 9, 2014

October 9, 2014

Period 2: We worked on the sugar lab report. You did very good work and I am very proud of the work I have seen so far.

Period 3:

Tuesday October 14, 2014

Tuesday October 14, 2014

Today we were going to introduce molecules, and build them with gumdrops. We were going to get a visual understanding of how molecules fit together.

However since 'everyone' is busy saving lives by giving blood we are altering our plans. Today, if anyone even shows up, we will be doing periodic table bingo. We will be exploring the periodic table, its characteristics and properties.

Friday October 10th, 2014

Friday October 10th, 2014

Today the lab reports were due. I received exactly 4 reports, all of them fantastic!

Everyone partnered up and researched discussed the following terms:

1. Periodic Table

2. Valence Electron
3. Atom
4. Electron
5. Proton
6. Neutron
7. Metal
8. Non-metal
9. Alkali Metal
10. Noble Gas
11. Halogen Gas
12. Transition Metal
13. What are the parts of the periodic table

Then we did a really simple exit test, 5 questions. All taken directly from the above list. Everyone scored 100! I received some really amazing answers!

Wen October 8, 2014

10/8/2014

Period 2: We will finish the Sugar cube lab and start work on the lab reports.

Period 3: We will be compiling a list of ways you use or will use chemistry. We will also discuss what we want to learn in chemistry.

Tuesday, October 7, 2014

Tuesday, 10/7/14

Lab Report Guidelines

Format:

-Size 12 font (times new roman, arial, similar)

-1 inch (standard) boarder around the document

-Double spaced

Note:

-You must write a lab report by yourself. Plagiarism will not be tolerated.

Primary	Details	Points	Total Points Available
Format		___/10	10
Introduction			15
	Background Information	___/5
	Purpose of the Experiment	___/5
	Hypothesis	___/5
Procedure			20
	Materials	____/5
	Procedure	___/15
Results			30
	Table with labels	___/10
	Graph with labels	___/10
	Description of Data	___/10
Discussion			25
	Conclusion	___/10
	Explanation of Results	___/10
	Future Experiments	___/5
Total			_____/100

Friday, October 3, 2014

Friday,

Today we finished planning for the sugar cube lab:

Plan and carry out three experiments to find the fastest way to dissolve a sugar cube in water. Students are limited to one sugar cube an experiment and 30 mL of water per experiment. Most groups finished their experiments. One group will finish on Tuesday.

On Tuesday we will finish the lab and start work on the lab reports.

Lab
Rubric

Thursday October 2, 2014

Thursday,

Today we reviewed atoms, worked on the Lewis Dot structure and finished work that had gone unfinished. We also started planning for the Sugar Cube lab

Lewis Dot Worksheet 1
Lewis Dot Worksheet 2 (part 1)

Wendesday October 1st 2014

The Great Review!

Today we reviewed everything we have covered in class so far. 

-Atoms

-Parts of atoms

-Relative charge of parts

-Size of the proton, neutron and electron

-States of Matter

-What each state looks like at the molecular level

-The Periodic Table

-What the alkali metals, alkali earth metals, transition metals, halogens, noble gasses and metalloids are

-Properties of metals

-Properties of nonmetals

-Properties of metalloids

-Valence electrons and what they mean

-How many valence electrons each column has

-Atomic number

-Atomic mass

-SIgns of a physical change

-Signs of a chemical change

-Meter

-Liter

-Gram

-Miniscus

-Measureing a pencil

-Massing an object

-Using the balence

Tuesday September 30, 2014

We finished up work on the super hero/villain poster!

The posters are looking great!