Collegechemistry

We found 20 articles

How to solve an empirical formula problem
In this blog post, we will review how to determine the empirical formula of a compound using the mass percentages of the elements from which it is formed.
Quantum numbers
In this blog post, we explore the four quantum numbers, which allow us to describe the properties of each electron within an atom. According to the Pauli Exclusion Principle, no two electrons can share the same combination of quantum numbers. A carbon atom has six electrons, for example, and each of these electrons can be described by one of six ...
A painless introduction to VSEPR theory
Today we will discuss VSEPR (pronounced “vesper”), which stands for valence-shell electron-pair repulsion. The basis of VSEPR is that the electrons in bonds and lone pairs repel each other. To minimize the instability that results from these repulsions, a molecule will adopt the shape that places electron groups as far apart as possible. VSEPR ...
Tips for success in organic chemistry courses
Organic chemistry is historically considered a “weed-out” class for pre-medical students and often the cause of much frustration for students. After spending 3 years during college serving as a teaching assistant and tutor for organic chemistry courses at my undergraduate university, here are some tips for studying for your organic chemistry ...
Drawing the chair conformation of a pyranose ring
Welcome back! In this blog post, we will complete the following example problem:
How to balance redox reactions in acidic and basic solutions
Balancing redox reactions is an essential skill for the Chemical and Physical Foundations section of the MCAT, the GRE Chemistry Subject Test, and the AP Chemistry Exam. Today, we will learn how to use the half-cell method for balancing redox reactions in acidic and basic solutions. We will first balance a redox reaction in acidic solution, then ...
I just want to be a doctor, so does organic chemistry really matter?
Imagine: you’ve made it through your first semester or two of undergrad and weathered all the storms that come with this transition. And, now you find yourself facing a dreaded academic giant that has stricken fear in the hearts of scores of pre-medical students. A chemistry course unlike any other. If you are anything like most pre-medical ...
So, what is chemical engineering for, anyway?
Chemical engineering is a comprehensive and vast field of study with far-reaching impact. I have been a practicing chemical engineer in the biotechnology industry for the last 5 years, and prior to that, I earned my doctorate in chemical engineering at the University of Wisconsin, Madison. Over the last 10 years, I have seen the evolution and ...
Dimensional analysis: why the factor-label method is a lifesaver
Ever lost points on a test because you forgot to write the units? Rightfully so! Numbers have no meaning without their units of measurement. Two can be greater than 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 ...
Formal charge: what they didn’t tell you in your chemistry class
Formal charge is the charge that a bonded atom would have if its bonding electrons were shared equally. Note:
Golden rules to nuclear magnetic resonance spectroscopy (NMR) analysis: part 1
Nuclear magnetic resonance spectroscopy, or NMR, is a fundamental analytical technique used by chemists to determine the structure of organic compounds. Unlike other analytical techniques, such as infrared spectroscopy or mass spectroscopy, NMR allows for the complete interpretation of molecular structure and can be quantitative.
Two ways to determine equilibrium position in organic chemistry
A common exam question that comes up in both Orgo 1 and Orgo 2 requires students to determine a reaction’s equilibrium position. The question usually looks something like this: 
How to get oriented to organic chemistry: 7 pillars of the course
Organic Chemistry (OChem or Orgo) seems like a scary course. But it should not be if you know what to expect. This road map is your guide to orientate yourself to Orgo1. It teaches you about the main topics covered in Orgo1 in the typical order they are taught in class. So, take a breath and sit back as you read, skim, or view the images that ...
Orgo 1 strategies: protocol for acid-base problems
  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 ...
What is the phospholipid bilayer and what determines its fluidity?
All cells are surrounded by a cell membrane that forms a barrier between the cell and its surroundings. This membrane is often referred to as the phospholipid bilayer. As you can probably tell from the name, a phospholipid bilayer is made up of two layers of lipids. The fluidity of this membrane must be maintained within a certain range for the ...
Tips and mnemonics for memorizing amino acid structures
Learning amino acid structures is a challenging part of biology and biochemistry coursework. Many students feel totally overwhelmed by the task. The best way to master this skill is lots of repetition (here is a link to a Sporcle quiz that may help you with the repetition part) but it can be helpful to have tricks and mnemonics to get you started. ...
A guide to deciphering chemistry arrows
Chemistry is confusing enough with IUPAC nomenclature procedures to know, and the difference between E/Z and cis/trans alkene descriptions, and so many other new terms, models, units, and symbols. But the most common and important symbol in chemistry is the arrow.
The basics of retrosynthesis
People often dismiss organic chemistry as “all memorization”. I disagree – organic chemistry is just a series puzzles based on a few basic concepts (electronics, sterics, orbitals) that come together to answer almost any problem you might encounter on your homework or tests.