Covalent Bonding

On Thursday, we learned about Covalent bonding. Simply, this is the "sharing" of electrons to reach a full valence level. Covalent Bonding only happens between two nonmetals.

Covalent bonding can occur in single, double or triple bonds. It cannot occur in quadruple bonds. That is why carbon cannot form a C2 compound to fill its valence level.

Compounds are diagrammed in Lewis Dot Structures. These diagrams can be simple:

Or very complex:

Just throwing elements together can really be complicated if you do not do it right, however. But Mr. Lieberman, being the great teacher he is, gave us a few of guidelines to draw them:

1. Count the # of valence electrons (total) in the compound. Remember to keep ions intact.

2. Predict the arrangement of atoms in the compound. The first atom in the formula is generally in the center, unless it's Hydrogen.

3. Form single bonds, and see how many valence electrons are still left over.

4. Place electrons around the exterior elements until they have a full valence level, then do the same for the center atom. Remember, their can only be 8 total electrons around each element, unless it is on a row with transition metals.

5. If more electrons are needed, draw double and triple bonds.

And then you've got a Lewis Diagram!!!! (That was fun, wasn't it). The next scribe will be: MEEEEE :(

Lots of Reactions

In class today, we started a lab with many different sodium and nitrate groups, totaling 48 reactions. Why would we do that many, you ask? Well it has to be either:

a) Mr. Lieberman likes to make us do a ridiculous amount of writing and balancing equations

b) To help us formulate rules on formation of precipitates.

or c) All of the above

I'm Gonna go with C.

To start off, we put various solutions containing water and a Sodium Ion in each column. Then, we added a Nitrate solution to each of those, receiving varying results:

Some did absolutely nothing, leaving a clear liquid behind.

Others changed colors, but no precipitate formed.

Still others formed either a cloudy or completely solid precipitate, meaning that a reaction occurred.

And a couple did this:

Just kidding. But still, it was exciting. Here are the real results:

And my data table, if you can read it:

And the post lab is the real fun part: we have to write chemical equations for EVERY SINGLE PRECIPITATE! Both molecular and net ionic. For example, the molecular equation would be: 3Na₂SO₃+2Al(NO₃)₃ yields Al₂（CO₃）₃+6NaNO₃ and the net ionic equation would be: 2Al³⁺+ 3CO₃² yields Al₂(CO₃)₃. And repeat. About 20 times. Just a thrilling homework assignment. Oh, and by the way, for those who can't realize it yet: NaNO₃ is a product for every single molecular reaction, and always dissolves.
Thank you for reading my post. I hope you all do wonderful on your labs now. Now, the next scribe will be:.............................................

Ben A.

What's Wrong with a Little Change?

To start Chemistry class today, we discussed the Mixtures Lab (due tomorrow), and Mr. Lieberman asked if there were any questions. Question number 6 seemed to be confusing. Mr. Lieberman explained then to ignore it, or write the mass percent of each substance in the mixture.

Next, after turning in the Paper Clip worksheet from last week, we took notes on a powerpoint about chemical and physical propertieds and changes. Remember:
a Physical Propety is one that can be observed without a new substance being formed (ex. boiling point, melting point, texture, etc.).
a Chemical Property is a property that tells us how a substance would react in a given circumstance (ex. at what temperature does cinnabar split into mercury and oxygen?)
a Physical Change is a change that can be observed without the formation of a new substance, including change of phase. (ex. water freezing, boiling, a rock being smashed).
a Chemical Change is a change of a substance into a brand new substance. (ex. a bomb exploding, wood burning, banana ripening).

Finally, went over the prelab for "What Chemical Reactions?", which discusses properties and changes, and also determines that "corrosive," a property of HydroChloric acid, means damaging to skin and clothes, and then started the lab. Most of the groups did not get far because of limited time, but we did get to see some Chemical reactions. We will finish it tomorrow.

Sorry no pictures... I didn't get any good ones. The next scribe will be: Ben T