Tuesday, January 30, 2007
Mistakes to avoid
I do NOT want to rant after tomorrow's test. So, HEED THIS (ANTI-)ADVICE!
Instead of repeating the same explanation over again, here is a list of things NOT to write on the Honor's exam. The following are a list of absolutely unbelievable distortions that I NOT ONLY have explicitly showed you how to avoid and WHY you should avoid them (because they are patently ridiculous) BUT ALSO that I have never ever even remotely suggested them as legitimate phenomena or explanations:
1. NEVER EVER EVER call an F-H, O-H, or N-H covalent bond WITHIN a given molecule a "hydrogen bond". ANY BOND that involves the SHARING of electrons BETWEEN TWO nonmetal nuclei is BY DEFINITION a COVALENT BOND!
(Hydrogen "bonding" is merely an intermoleculare attraction, NOT BETWEEN ATOMS, but between SEPARATE and DISTINCT molecules; each molecule MUST have an F-H, O-H, or N-H covalent bond WITHIN the molecule in order to be polar enough to have extreme dipole-dipole attractions.
2. NEVER call hydrogen bonding attractions MERELY dipole-dipole attractions. THERE NEVER WOULD EVEN BE a separate category CALLED hydrogen bonding attractions if they were not (INTENSELY) EXTREME dipole-dipole attractions.
3. NEVER EVER EVER WRITE THAT IONIC BONDING HAS ANYTHING TO DO WITH ZEFF OR ELECTRONS!!! IONIC bonds ARE BONDS between and AMONG OPPOSITELY CHARGED IONS (CATIONS AND ANIONS), NOT ELECTRONS SHARED BETWEEN NUCLEI!!!
YOU WILL SEE ionic bonds form EVERY TIME there is a compound of a METAL AND A NONMETAL and NEVER in a compound of NON-METAL and a NONMETAL.
4. NEVER say that a nonpolar molecule is NOT ATTRACTED TO or (even worse!) REPELLED by a polar molecule! ALL MOLECULES ATTRACT EACH OTHER BUT polar molecules attract other polar molecules to a greater degree BECAUSE polar molecules have PERMANENT and relatively GREATER partial negative and partial positive regions to each molecule than do nonpolar molecules.
5. IF YOU BOTHER to take the time to draw a picture of what you are talking about, REFER TO YOUR DRAWING REPEATEDLY THROUGHOUT YOUR EXPLANATION!!! EVERY SINGLE TEST, TIME AFTER TIME, PEOPLE FORGET TO DO THIS AND, AS A RESULT, THEY LOSE CRAZY POINTS EVERY TIME!!!
6. DO NOT WRITE OUT YOUR ENTIRELY REHEARSED ANSWERS IF THEY ARE NOT RELATED TO THE QUESTION!!! NO WONDER YOU RUN OUT OF TIME!!! I cannot tell you how many students wrote paragraphs of irrelevant facts such as explaining that "solid salts do not conduct electricity" EVEN THOUGH SUCH A QUESTION DID NOT REMOTELY EXIST ON THE LAST TEST!
7. IF you do not yet know how to go from formula to name and vice-versa for any type of compound that we have covered so far, then you are going to lose A LOT of points on tomorrow's test. You cannot do math of chem or any kind of chemical equations unless you know how to name compounds and how to write formulas from names.
MAKE ABSOLUTELY SURE that you are bulletproof on naming or you are not going to do well.
Instead of repeating the same explanation over again, here is a list of things NOT to write on the Honor's exam. The following are a list of absolutely unbelievable distortions that I NOT ONLY have explicitly showed you how to avoid and WHY you should avoid them (because they are patently ridiculous) BUT ALSO that I have never ever even remotely suggested them as legitimate phenomena or explanations:
1. NEVER EVER EVER call an F-H, O-H, or N-H covalent bond WITHIN a given molecule a "hydrogen bond". ANY BOND that involves the SHARING of electrons BETWEEN TWO nonmetal nuclei is BY DEFINITION a COVALENT BOND!
(Hydrogen "bonding" is merely an intermoleculare attraction, NOT BETWEEN ATOMS, but between SEPARATE and DISTINCT molecules; each molecule MUST have an F-H, O-H, or N-H covalent bond WITHIN the molecule in order to be polar enough to have extreme dipole-dipole attractions.
2. NEVER call hydrogen bonding attractions MERELY dipole-dipole attractions. THERE NEVER WOULD EVEN BE a separate category CALLED hydrogen bonding attractions if they were not (INTENSELY) EXTREME dipole-dipole attractions.
3. NEVER EVER EVER WRITE THAT IONIC BONDING HAS ANYTHING TO DO WITH ZEFF OR ELECTRONS!!! IONIC bonds ARE BONDS between and AMONG OPPOSITELY CHARGED IONS (CATIONS AND ANIONS), NOT ELECTRONS SHARED BETWEEN NUCLEI!!!
YOU WILL SEE ionic bonds form EVERY TIME there is a compound of a METAL AND A NONMETAL and NEVER in a compound of NON-METAL and a NONMETAL.
4. NEVER say that a nonpolar molecule is NOT ATTRACTED TO or (even worse!) REPELLED by a polar molecule! ALL MOLECULES ATTRACT EACH OTHER BUT polar molecules attract other polar molecules to a greater degree BECAUSE polar molecules have PERMANENT and relatively GREATER partial negative and partial positive regions to each molecule than do nonpolar molecules.
5. IF YOU BOTHER to take the time to draw a picture of what you are talking about, REFER TO YOUR DRAWING REPEATEDLY THROUGHOUT YOUR EXPLANATION!!! EVERY SINGLE TEST, TIME AFTER TIME, PEOPLE FORGET TO DO THIS AND, AS A RESULT, THEY LOSE CRAZY POINTS EVERY TIME!!!
6. DO NOT WRITE OUT YOUR ENTIRELY REHEARSED ANSWERS IF THEY ARE NOT RELATED TO THE QUESTION!!! NO WONDER YOU RUN OUT OF TIME!!! I cannot tell you how many students wrote paragraphs of irrelevant facts such as explaining that "solid salts do not conduct electricity" EVEN THOUGH SUCH A QUESTION DID NOT REMOTELY EXIST ON THE LAST TEST!
7. IF you do not yet know how to go from formula to name and vice-versa for any type of compound that we have covered so far, then you are going to lose A LOT of points on tomorrow's test. You cannot do math of chem or any kind of chemical equations unless you know how to name compounds and how to write formulas from names.
MAKE ABSOLUTELY SURE that you are bulletproof on naming or you are not going to do well.
# posted by C @ 1:20 PM 
