Dimensional Analysis: Why the Factor Label Method is a Life Saver

Posted by Viemma on 12/14/18 2:22 PM

Ever lost points on a test because you forgot to write the units?

Rightfully so! Numbers have no meaning without its unit of measurement. Two can be greater the 12. Three can equal one. This is all dependent on the unit of measurement being used. In your general chemistry class, you will encounter measurements of all sorts. These measurements include time, length, mass, volume, and many more. Units of measurement are used to conceptualize the magnitude of these measurements. Gram, kilogram, pound, ounce, metric ton, stone, slug, microgram, atomic mass unit, carat… these are all units of measurement for mass alone. Why so many? Some units of measurement are more appropriate depending on what thing is being measured. Using an inappropriate unit of measurement may result in a number value that is too large or too small. When this happens, it becomes very difficult to wrap your head around the magnitude of the measurement. 

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Tags: chemistry

Electron Configurations: A Must Know Hack

Posted by Viemma on 12/12/18 3:15 PM

Imagine this…

You’re taking your general chemistry midterm and you’ve decided to shuffle through the exam and complete all the hard things first. You’ve totally underestimated how much time those problems were going to take you and now you have three minutes left to write the electron configuration of 10 elements. Untimed, this would be easy to do. It’s systematic and straightforward but still requires a decent amount of thought based on how you were taught to do it. Your palms get sweaty. These are supposed to be easy points and there’s a possibility that you won’t complete it. If you do complete it, there’s a possibility that you’ll get them wrong because you were rushed. Your throat is getting tight at this point. You’re trying to recall if you were confident about the other questions you have already done, wondering if you can afford to lose these easy points in front of you. Your teacher announces that there are two more minutes before he starts collecting exams.

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Tags: chemistry

Formal Charge: What They Didn’t Tell You in your General Chemistry Class

Posted by Viemma on 12/3/18 10:14 PM

Formal charge is the charge that a bonded atom would have if its bonding electrons were shared equally

  • It is not an actual charge but rather a form electron book-keeping
  • The sum of formal charges should equal the compound’s actual charge
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Tags: chemistry

Orgo 2 Strategies: “Taking Home” Carboxylic Acid Derivatives

Posted by Andrew S. on 10/30/17 6:22 PM

I’ve already covered how to easily manage carboxylic acid derivative formation and manipulation using the Reactivity Hill.

Say we’re tired of whatever derivative we just created and want to bring the derivative back to its parent acid (the particular acid the derivative came from). There are two ways to “take home” any acid-derivative. We can account for these “take home” conditions in the Reactivity Hill scheme we’ve already seen.

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Tags: chemistry

Organic Chemistry: This Subject Gives You Alkynes of Trouble!

Posted by Daljit on 10/27/17 4:39 PM

Although some people genuinely enjoy it, organic chemistry is stigmatized as the bane of every science major's curriculum. Before you actually take one or two courses in this subject, the horror stories that you've heard from those who have already taken these courses fill you with anxiety and leave you fearing the unknown. I'm not going to sugar coat it: organic chemistry is difficult but not impossible. As long as you devote enough time to study for the exams and figure out an effective study system (I used flashcards), you will be fine when it's all said and done. If you have ever taken an organic chemistry class or if you are currently taking one now, you know that there are feelings and experiences that only a past, or current, organic chemistry student understands.

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Tags: chemistry

Orgo 1 Strategies: Understanding Hybridization

Posted by Andrew S. on 8/30/17 5:30 PM

Your professor gives you the below molecule. Can you quickly determine the hybridization of every atom?

Determining and understanding hybridization in Orgo 1 isn’t a futile practice. It’s an idea key to understanding mechanism and reactivity all the way through Orgo 2. Thankfully, the rules of thumb used to determine an atom’s hybridization are fairly straightforward. For example, most students recognize that..

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Tags: chemistry

Orgo 1 Strategies: Finding and Comparing Alkene Hydration Products

Posted by Andrew S. on 7/31/17 6:18 PM

We all know Orgo 1 professors love stereoisomers. Consider the question A + B = C. Most professors expect you to fill in the question mark with all possible products and then indicate the major product(s), while other professors may provide you a potential C and then ask you if the statement is True or False.

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Tags: chemistry

Orgo 1 Strategies: The Power of Bromine in Synthesis

Posted by Andrew on 7/10/17 5:49 PM

Whether you’re trying to accomplish a substitution or elimination in your synthetic scheme, there’s no getting around that a good leaving group must be involved. You’ll have a host of ways to introduce leaving groups by your final exam. Some reagents will invert chiral centers (e.g. SOCl2/pyridine, PBr3) in the process, and others won’t. 

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Tags: chemistry

Orgo 1 Strategies: Two Red Flags to Guide Your Synthesis

Posted by Andrew S. on 7/7/17 5:39 PM

So your professor says your Orgo 1 final will have a few synthesis problems. The good news: you’ve only learned a handful of reactions. Namely, you’ve learned how to manipulate alkenes and alkynes, and you know a little about radicals, substitution versus elimination, and the chemistry of alcohols, thiols, ethers, and epoxides. The bad news: well–there’s none to give. Managing synthesis problems in Orgo 1 is easy when you learn to look for red flags! 

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Tags: chemistry

Orgo 1 Strategies: Protocol for Acid-Base Problems

Posted by Andrew S. on 7/5/17 5:53 PM

Determining which of two molecules is more acidic is tricky if you haven’t yet organized those factors that influence acidity. The protocol is a method I learned from my mastermind Orgo 2 professor to keep these ideas in order when they come into conflict. Namely:

Size is more important than

Electronegativity, which is more important than

Resonance, which trumps the

Inductive Effect.

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Tags: chemistry