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There are two classes of nucleotides in DNA: pyrimidine and purine, and four nucleotides: cytosine, thymine, adenine, guanine. Easiest way to remember to which class they belong is that all pyramidines (cytosine and thymine) contain the letter y.
As well, adenine and guanine are nine-sided molecules, and the pyramidines are six-sided molecules. See the animation showing how a six-sided molecule becomes a pyramid.
Although DNA and RNA are both nucleic acids, they do different jobs in the cell. Just remember:
There are two simple sugars (monosaccharides) -- fructose and glucose -- which combine in a specific way to form sucrose. Remember the molecule of Fructose has Five carbons (letter F starts both words) and hexaGon is the shape of the Glucose molecule (letter G in both words). Remember too, if fructose and glucose attach the wrong way, you end up with an undigestible fibre instead of sucrose sugar.
Insulin gets sugar into cells. Without insulin, a person can have excess sugar in his blood yet die of lack of sugar. Excess sugar is removed via urine. Romans noticed bees attracted to the urine of diabetics and coined the term "diabetes" to describe the overflow of sugar. (literally, diabetes = "across the sugar"). Medical students need to distinguish between the two types of diabetes: mellitus and insipidus. Both cause increased urine flow, but for different reasons altogether. D. mellitus is characterized by excessive sugar present in the urine due to lack of insulin. D. insipidus is recognized by high volumes of watery urine due to lack of anti-diuretic hormone (ADH), usually caused by a damaged hypothalamus gland. In the old days, a physician would taste the urine to determine which form of diabetes his patient had.
Water rises to the tops of plants by Capilliary Action (CA), which depends upon Cohesive and Adhesive (C+A) properties of H2O.
Hydrolysis is the way water can break molecules (hydro=water, lysis=cut). Certain molecules called monomers (mono=one, mer=water*) have a hydroxide and a hydrogen attached to the side. When a monomer bonds to another monomer or polymer, the HO and H atoms break off and combine to form a single water molecule. You can see the effects of hydrogen bonds in real life whenever you iron cotton fabric. Cotton is a long cellulose chain with H-bonds attaching it to other cellulose chains. When these bonds link out of parallel, we get wrinkled clothes. Heat and moisture (i.e., steam iron) break and reform these bonds to a more parallel shape. Wool has covalent and electrovalent disulfide bonds which can be permanently set (permanently pleated) by breaking and reforming these bonds with certain sulfur chemicals. Nylon, polyester, acetate, and triacetate are thermosensitive and their shapes can be heat set.
* ~mer actually means "piece" in Greek and "sea" in French, but I found this way makes it easier to remember.
To remember how osmosis works, remember that "Particles suck." Thus, tonicity (hypertonic, hypotonic) refers to concentration of particles, and water always goes toward the area of more particles.
(from: Hallie Ray, Science Department, Rappahannock Community College, Warsaw, VA)
Two easy bond angles are also two of the more common ones we need to memorize. Sure, it is hard to remember which molecules have what angles, but it is important if you want to make any money as a chemist of any note. The H2O molecule is bent because the extra electron cloud sticking out of the oxygen atom pushes the two hydrogen atoms away, thus making an angle of 105 degrees instead of a straight line. Similar thing with NH3, except the electron cloud pushes against the three hydrogens to modify the regular tetrahedral shape a bit. To be precise, the angle between the hydrogens and the central nitrogen is 107 degrees. How do I know this? Because I count the letters in WATER and AMMONIA and come up with 5 and 7 respectively (to correspond with 105 and 107 degrees respectively).
Although reports have surfaced of people committing the naturally occurring elements to memory simply by reciting the symbols as a crazy sentence that starts "Hy! He libeb cnof nenam gal sips clark casa tiv crmn feconi cuzn gage ass ebr krrb styz rnb mot crurh pdag ..." we will refrain from attempting something so dangerous. Instead, I present the following:
Like Being Bare Cuz Naked Orgasms Feel Neat for lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon. Or the more risque Lithesome Beryl Blows Charlie Nightly On Floor Neeling.
Once you see this word pattern in the third period (Na, Mg, Al, Si, P, S, Cl, and Ar) you'll always remember that Nagging Maggie Always SiPS ClAret.
PoKey Captain Scans Tight Virgin Crew Members Fer Cold Night Cuddles. Zany Gray Germs Are Sold By Kremlin, or in reverse order: Kry Brother! SeAs of Germany and Gaul Sink Copper ships Nice and Cold from Manx to Crimea, Vancouver to Timor, and Scandinavia to the California Koast.
Rub Strong Young Zulus. Nubile Mona Touches Ruth's Rectum. Pallid Agents Could Infiltrate Tiny Stubborn Telephone Industry Xecutives.
This row on the left lower portion of the table contains Cesium, Barium, Lutetium, Hafnium Tantalum, Wolfram (tungsten) and Rhenium. Just remember: Cheap beers lure half-tanked wolf and rhino. The rest of them might go Osir: pretty awful hag throws pretty bad polkas all right for osmium, iridium, platinum, gold, mercury, thorium, lead, bismuth, polonium, astatine, radon. Another: Osir, platinum-blonde Audrey hogs Thor, plumbs Bill, and polos at random.
Elements #57-71 have two cute mnemonics: Little Cute People Need Plenty Sex Every Given Time Despite having Enough Through Young Love and Currently Parties Never Provide Sexy English Girls That Drink Heavily, Even Though You Look.
Berkelium, Californium, Einsteinium, Fermium, and Mendelevium are a snap when you recite: BlocKheads Can't Find ElementS FroM Mnemonic Devices
Only Silly Asses In College Study Past Midnight tells me that the most common elements of the planet's crust are, in descending order: oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium.
HONC if you like Life!
Of course, H-O-N-C are the four elements that make life's building blocks -- hydrogen, oxygen, nitrogen, and carbon.
All 18 groups (columns) of the periodic table are mnenomicized here in order:
Bonus The metalloids mnemonic is: Big Sized Genitals Assure Teasing Stories.
Tip: memorize groups I and VIII, and one period to start. Whenever I need to sketch out the Periodic Table, I write down the first and last groups, add the periods that I know, then fill in the blanks using what I've written down as a guide.
Here's a phrase for remembering atomic properties: Prostitutes Outnumber Nice Electioneers. Number of protons = atomic number (PROstitutes outNUMBER), neutrons determine isotope (NIce), and electrons determine ionization (ELECT-IONeers). Also, Cat Lost an Eye is good for knowing that cations are atoms which lost an electron.
Some students find it hard recalling the letters designating atomic energy levels. Originally, they were named after qualities seen in spectroscopy and later associated with electron energy level. Thus, the qualities of sharp, principle, diffuse, and fundamental (s, p, d, f) have no relation to electrons. Nevertheless, my chem prof taught us to Ski Powder Deep and Fast. Use PAM to remember the three quantum numbers: Principle, Azimuthal, Magnetic spin. Another one is to think of an Arab publisher: Azim Prints a Magazine.
Furthermore, PAM has a More Shapely Sizin' where MORE = magnetic orientation, N = size, and l = shape of electron orbits.
Dave, a once-in-a-while bright student, was sitting next to me doing his quantum calculations which involve the Planck constant -- 6.626 x 1034. I told him the number from memory, he asked me how I knew it. I asked "how many letters are in Planck's name? " (6), then I said "Planck drove an older Mazda sedan (a 626), and his 34th birthday had a negative effect on him." He chuckled and groaned. Twenty minutes later, he said "John, I can still remember that number".
Easy to remember that Rydberg's Equation is used to analyze spectra ... "RYDBERG" contains most of the colors of the rainbow: red, yellow, dark blue, orange, green. That formula is: 1/lambda = R(1/n1 squared minus 1/n2 squared)
The ABCs of gas law are Avogadro, Boyle, and Charles. Each contributed a variation to the standard PV=nRT equation (Perfect Virgins are Not Real Things) for calculating gas pressure, volume, mass, and temperature. Easy to remember who came up with which law -- they were all sick! Avogadro was ugly (his face had a number of moles); Boyle had high blood pressure due to diabetes; Charles ran a temperature. A fourth scientist, Gay Lussac, contributed his formula for calculating variations in temperature and volume whilst pressure was constant. In fact, Lussac, Boyle, and Charles all can be remembered by their individual formulae relating to Gas Law:
The only way I could remember the differences between SN1, SN2, E1, E2 reactions were to make up stories about what I imagine is happening. If you don't think you'll enjoy this story, then go to the Virtual Chem Page and click on Organic Synthesis to see animations of SN1, SN2.
Substitution reactions come in two flavours: slow (SN1) and quick (SN2). They produce different products in differing ratios as well. While in lecture, I thought the nucleophile sounded like a paramour, and the leaving group was a loser in the deal, and if those molecules were people, they would be on a soap opera. So, I doodled and came up with names that relate to the reaction and are easy to remember. There are more details, but for now, let's just read a couple of short stories to get the general idea of each.
SN1 (Soap Network 1) is suffering low ratings. It was supposed to be a hot show but it is pretty slow. The scene: On an aeroplane (airplane to Americans) Levi and Nel are having a boring breakfast together. Nel poured some alcohol (a polar - protic solvent) into his coffee then told him to take a hike. As Levi was the pilot anyway, he left. Luke, a stowaway, then came along to woo Nel. "I'm too cold" she said, but Luke was looking at her huge bum and realized that type of hindrance would really slow things down, and that he would have to have a few intermediate steps along the way. Besides, the room for error would mean half the children might be born racemized. While Luke wanders around trying to decide is he should come in through the back door or be conventional, Nel just plays with the feline she calls Carbo-cat. When she and the cat double up and bond, Luke is eliminated.
SN2. To get ratings back, Soap Network 2 was launched. A more racy script with competent actors and director, this show really socks it to them. All three characters have had their apathy replaced by three new psychological disorders. Nel has Electra complex, which is a real plus; Drew is in denial, and Luke suffers proto-Oedipus complex. Nel's emotionally bipolar; her emotional energy rises as Drew gets ready to leave then peaks the moment he walks out the front door and Luke enters the same door disguised as a television repair man. Their affair is quick and passionate, but always inverted. As time went on, some of Nel's sons consumed some anabolic hormones and managed to beat the crap out of Luke whenever he came around. This is called the Steric Effect.
Refer to the adjacent picture for clues to the five ways of changing acidity of a molecule.
- N is for the nitrogen at the top that is more electronegative than carbon. Thus a hydrogen attache to nitrogen is more acidic.
- H is for the hydrogen bond between oxygen and hydrogen. H is also for the hybridization of the carbons on the left side.
- 3 are the bonds between the two sp hybridized carbons.
- OH! Resonance.
- Clinduction is chlorine's induction force on the structure. (Cl-induction)
- Cis looks like lips puckered for a kiss.
- Trans looks like a train ran over those lips.
- Conning Old Prelog means Cahn-Ingold-Prelog Sequence Rules, with one rule for each name.
- Newman and Fischer Projections are useful but confusing. I remember Newman projections are two superimposed circles, because MAD magazine's Alfred E. Neuman has a round face. Fischer projections use a cross, and so I think Emil Fischer was Christian.
- The Nitrogen Bonding Nitrile compounds have Nitrogen in a triple bond with carbon.