Helpful Chemistry Site of the Week.

Today’s site of the week is www.chemicalforums.com.  I have been a part of this site for a while, and have been pretty impressed with it so far.  Once you register, you can post chemistry questions for the experts to answer.  The experts are extremely knowledgable, and you get a bunch of responses in a very short time.  Great resource for the undergrad who wants a quick answer to a topic that has eluded them to this point.  An even better resource for the grad student who wants to run a research idea by a 10,000 lb brainiac.

This site gets 4.5 beakers out of 5.

For further information on this, please see organic chemistry.

Chemistry, Electricity and the Environment

During the election cycle, there was much discussion about our energy future.  I imagine that it clear to most that we can not continue to live on Middle Eastern oil forever, but what are the options?  Clean coal technology? Wind? Solar? Nuclear?  Natural Gas?  The choices are numerous and complex.  Further, and maybe more importantly, we must consider the impact on the environment. 

For those of you living in the great state of Texas, you have options.  One of them is Texas Electricity.  You have the choice to save on commercial electric, business electric and residential electric by switching to deregulated electric supply at Texas Electric Company. 

What impresses me is the ability to save the environment, with numerous “green” electric options.  Clean, renewable energy options will keep greenhouse gases like CO2 from being placed in our atmosphere and lead to a measurable decrease in global warming over the coming year.  You can do your part to help with that by visiting Texas Electricity. 

Pollution free electricity is clean, affordable and reliable power.  you can learn more about this and other options for your residential and business power needs by visiting Texas Electricity.  Remeber, this is our chance to leave the Earth better for our children than we found it.

Know your strong nucleophiles

This is important throughout organic chemistry, but will be especially important when trying to determine the products of elimination and substitution (E1, E2, SN1, SN2)reactions.  There are generally three trends to remember when discussing how nucleophilic a reactant is:

1)      Size - Generally, the more linear and/or smaller the nucleophile, the more nucleophilic it will be.  This is because it can react at more sites and will not be sterically hindered if it is smaller or linear.

2)       Electronegativity- The more electronegative an atom is, the less nucleophilic it will be.   This is because more electronegative atoms will hold electron density closer, and therefore will be less likely to let that electron density participate in a reaction.  We see this in calculations and experiments that show nucleophilicity decreases as you get closer to fluorine on the periodic table (C > N > O > F)

3)      Polarizability- The more polarizable an atom is, the more nucleophilic it will be.   Polarizability is defined as the ability to distort the electron cloud of an atom, which allows it interact with a reaction site more easily.  Generally, polarizability increases as you travel down a column of the periodic table (I > Br > Cl > F)

 Below is a table of relative nucleophilic strength.  This is relative because nucleophilic strength is also dependant on other factors in the reaction, such as solvent. 

VERY Good nucleophiles	HS-, I-, RS-
Good nucleophiles	Br-, HO-, RO-, CN-, N3-
Fair nucleophiles	NH3, Cl-, F-, RCO2-
Weak nucleophiles	H2O, ROH
VERY weak nucleophiles	RCO2H

 

As shown above, as a general rule, the anion of a reactant will be a better nucleophile than the neutral form.  (i.e. RCO₂^- is a better nucleophile than RCO₂H)

For more information on this and other topics of organic chemistry interest, please visit organic chemistry

Know the “normal” state for common organic atoms

Structures of molecules can be difficult to piece together at first when you are just starting in an organic chemistry class.  One of the tricks that can greatly help with this is to know the uncharged or “normal” state for atoms that are commonly found in organic molecules.   Here is a table of the most common of those:

       – C has four bonds and no lone pairs

       – N has three bonds and one lone pair

       – Halogens (F, Cl, Br, I) have one bond and three lone pairs. 

       – O has two bonds and two lone pairs

       – H has one bond and no lone pairs

 

Three more rules:

-          C, N, O are central atoms, meaning that they will always be in the middle of your molecule.

-          H and halogens are terminal atoms, meaning that they will only have one bond and be at the ends of molecules.

-          With the exception of H, atoms in group I & group II are only counterions (+1 or +2 and not involved in resonance).

 

Remember, these rules are for when the atom is uncharged; this does not apply to charged atoms.  For example, a carbocation (a positively charged carbon atom) will have only three bonds with no lone pairs while a carbanion (a negatively charged carbon atom) wlll have three bonds with one lone pair. 

 

Notice that all of these atoms still follow the octet rule.  However, beware of atoms that do not follow the octet rule, as phosphorus is an example of an atom that can have more than an octet of electrons.  Shown below is triphenylphosphine oxide, a byproduct of the Wittig reaction. 

 

Elements with open d-subshells, like phosphorous and sulfur, do not always follow the octet rule.  More examples of this are SF₆ and PCl₅.  However, carbon, nitrogen and oxygen will follow the octet rule. 

Beware of the bad acid trip: Know your strong acids

A problem we see students constantly running into is that they do not readily recognize strong acids.  This is a terrible mistake and should never happen.  You will need to quickly recognize strong acids and which atom they will be protonating.  As far as strong acids go, you should immediately recognize the Magnificent Seven:

 

STRONG ACIDS: HI, HCl, HBr, HNO₃, H₂SO₄, HClO₃, H₃PO₄

 

Just think that that it’s the three hydrogen halides and the four acids that have N, S, Cl, and P as central atoms.  Many students remember the other four acids with the mnemonic, something you would never say to a girlfriend: “Never Say ‘Please Clean’ ”. 

Once you have recognized that you have a strong acid present in your reaction, it is necessary to determine what it is protonating.  Remember that H⁺ is electron-deficient (Lewis acidic) and will look for an electron-rich (Lewis basic) atom to protonate.  This could be a nitrogen atom, such as an amine, or an oxygen atom in a carbonyl or an alcohol.  Most often, the atom being protonated will have a lone pair somewhere.

 

Take Home Message: Know the strong acids, the mnemonic Never Say ‘Please Clean’ might help

More for Your Inner Gambler

As many of you know, I am a huge gampbling fan and I just found out about USA Online Casino Bonuses.  This is a great site that hooks you up with the different bonuses that each online casino offers you.  Some of the bonuses are good, and some of them are great.  If you are going to play, you might as well get paid that extra amount in bonuses.  At USA Online Casinos, you choose from a bunch of casinos and find the bonus that is going to get you paid the most money.  Whether you game is cards, Blackjack or dice, they have the casino that is right for you.  My advice is to watch a good gambling movie to get you in the mood (21, or Ocean’s Eleven let’s say) and go to Top Online Casinos to get started.  Sign up is easier than splitting aces and you will be raking in the cash and working your mojo in no time flat.  It’s almost liek being in Atlantic City, except without the Mob.  Remember, you can’t win if you don’t get there.  Why not start out with some bonus money in your pocket.  They pay YOU to get out there.  All I do is find a casino I like and keep raking in that loyalty bonus. 

Good luck and, as always, happy reacting.

Search for Scholarships for FREE

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Learning Organic Chemistry is Like Learning Another Language

Learning organic chemistry is like trying to work in a foreign country where if you don’t know the language, it is going to be very difficult to learn how to do your job.  You have just been transported to the mythical country of “ochemia”, a small island nation in the south Pacific, where your job is to write chemistry reactions. 

Frequently, in a chemistry lecture, professors start tossing out organic chemistry terms far too quickly.  Because students aren’t fluent in “ochemia” yet, they need to translate each word in their head to understand what the instructor has just said.  By the time this mentally translation is done, the student has just missed the next sentence and has lost half of the lecture.  Our goal is to get as fluent as we can in the language of chemistry as quickly as we can.  Here are some terms it will be helpful to memorize so that you don’t have to do a mental translation when you hear them:

Meth = 1

Eth= 2

Prop = 3

But = 4

Pent = 5

Hex = 6

 Hept = 7

Oct = 8

Non = 9

Dec = 10

Electrophile = wants electrons, has a positive or partial positive charge

Nucleophile = has electrons, has a negative or partial negative charge

Halogen = F, Cl, Br, I

Aprotic solvents = do not contain OH or NH bonds

Protic solvents = contain OH or NH bonds

Lewis Acid = electron acceptor

Lewis Base = electron donor

Carbonyl group =  (C=O)

Cis = same side of a double bond or ring

Trans = opposite sides of a double bond or ring

 

 

A comprehensive organic chemistry glossary can be found at: http://www.chemhelper.com/glossary.html

 

As always, for more help in organic chemistry, please go to Organic Chemistry

Organic Chemistry Study Tips: Study In Packs

This reminds me of my favorite video on YouTube (http://www.youtube.com/watch?v=LU8DDYz68kM).  You are a pack of wildebeest, just chilling out by the water, trying to score a good grade in organic chemistry.  But you are being hunted by pride of hungry lions (your professors) who would like nothing better to make a quick snack of the weakest one of you.   After crouching in the brush, they suddenly pounce (pop quiz) and grab a hold of the smallest one of you (the student with the hardest course load). 

 

Two things can happen at this point:  Either the rest of the pack of wildebeest will cut their losses and try to save themselves or they can go back and heroically battle the lions to save their fallen colleague.  I am not going to ruin the video if you have not already viewed it, but I think you already know what happens. 

 

Studying in packs presents a number of benefits other than just altruistically helping a lesser student:

1)      Studies have shown over and over that studying in groups directly leads to higher grades of all involved.

2)      Studying in groups is generally more enjoyable for people, which leads to more time spent on the subject.

3)      If you are weaker in one area of the course, you have the opportunity to have a peer explain it to you.  Many students are more likely to understand a peer’s explanation over a stuffy professor’s.

4)      If you are stronger in one area of the course, you will strengthen your overall understanding of chemistry by teaching it to someone else.

 

Of course, when you are choosing study partners on the Serengeti, you need to be very careful to stay away from the jackals.  These are the students that are more parasite than human and will just leach off of your talents.  They are more succubus than man and will not help you much.   We suggest finding study partners that are interested in a good grade and are willing to put in the time necessary to achieve a good grade in the course.      

For more information and organic chemistry help, please go to organic chemistry

Learn to Gamble

So I stumbled across this site, online casinos where you can learn to play standard casino games for free.  Anyone who knows me will tell you that I am a huge Las Vegas fan, so us online casinos gave me even more of a reason to get back to playing.  Learning to play is simple and they have tutorials on blackjack, slots, baccarat, roulette and many other games that are found in your average casino.  At online casino us players you can at like a high roller, even when you are not.  I sat down last night and relearned how to play the exciting and challenging game of craps.  I love rolling dice, it is always a good time standing around the table shooting dice.  If you are new to it, I suggest reading the beginner’s guide on the site.  If you are true to it, I would suggest one of the advanced game guides or learning a new game that you might not be completely familiar with.  You can always teach an old dog new tricks. 

Of course, the other thing that one should do when picking a casino is to make sure that you get all of the signup bonuses that you can, but that is a topic for another time.