<p>what was the answer to the formal charge question, structure 1 or 2? we never learned about formal charge; our teacher told us that it hadn't been on the AP exam for the past several years, and wasn't really covered anymore.</p>
<p>Structure one because it had a zero formal charge on all 4 atoms in the molecule.</p>
<p>Yup. structure one indeed.</p>
<p>We did a few days of formal charge, but enough to know it well.</p>
<p>o shoot , silver sulfide is black.. i can't believe i put silver chloride is black.. our teacher never went over it.</p>
<p>My teacher never went over the silver sulfide/silver chloride thing either . . . . But I still got it, yay :)</p>
<p>sodium chloride is white, i didnt see why silver would be the completely opposite color.. and sulfur just sounds like it would be black</p>
<p>Sulfides are black, generally.</p>
<p>for the ionization energies. did any of you guys notice two of the ionization energies were a lot closer to each other? it was like 700,1000,1020. i said the last one element had repulsions. i forget what element it was though.</p>
<p>Oh Crap! Lol, I didnt think and put K2S was the one that precipatated... Haha, whoops. Does anybody know about how many points that part of the question will be worth? And how many points I would lose if I only got 1 of the substances right.</p>
<p>Haha</p>
<p>:)</p>
<p>For #7, I put:</p>
<p>a)</p>
<p>(i) Dipole-dipole, dispersion
(ii) NH3 is polar therefore more dipole-dipole, harder to break substance apart..</p>
<p>b)</p>
<p>(i) Both are ionic bonds
(ii) NaCl has more electrons + greater difference between electronegativity</p>
<p>c) </p>
<p>(i) All are n=3
(ii) More protons = greater pull, harder to lose electron</p>
<p>d)</p>
<p>(i) Magnesium or something. Dont remember...
(ii) 64.93, closer to element average amu</p>
<p>Did I get all of them right?????
or did i get a few mixed up...</p>
<p>For A: NH3 has Hydrogen bonding as well.
B: Na is smaller (or bigger, I dont remember what the other was) than the other, so the bond lengths and strengths would be different. I'm not sure, this is what I put tho...
D: I don't think it was what you put, but I'm sure you got it right cause its pretty hard to miss that one.</p>
<p>:)</p>
<p>Crap.. But they'll probably give me half-credit for 2/3</p>
<p>variance- I agree with all of your answers except your explanation for b. </p>
<p>With ionic bonding, the bond strength is determined by coloumb's law, which essentially says strength increases with increasing charge and decreases with increasing distance. Na is smaller, so it will have the stronger bonds.</p>
<p>Electronegativity only matters with covalent bonding.</p>
<p>OK, what percent do you think you'll need for a 3 this year?
Also, will I receive any credit at all for:
1. Saying that the difference in boiling points is due to one element having stronger intermolecular forces, meaning that the bonds will be harder to break
2. Getting n=3 for the first 2, but saying n=4 for the third one (I was looking at electron configuration, didn't realize it was so easy, just had to look at position on periodic table)
3. Saying that the isotope with the higher mas is more common, because the mass given is the average, and is closer to the higher one (even though it's closer to the other one)
4. Saying that the black precipitate is AgCl because AgCl is insoluble
Saying that KCl and AgS will form the "no reaction" one since salts are usually soluble
5.I identified the substances according to my answers according to what I got from the two above, using correct logic even though they were wrong
6. Saying the CF4 bond angle is 102.4, then saying tetrahedral angles in parentheses
7. Getting the wrong empirical formula in #2 but explaining my thought process, I just rounded wrong
Sorry, I'm just really nervous, I went into the test thinking I'll get a 4 or 5, and I made a dumb mistake on almost every problem, and forgot that we had a choice of 2 or 3 and 7 or 8, so I finished 2 and 7 each time before I realized I could have done 3 and 8, which I would have gotten full credit on, and I barely got any right answers on 2 and 7.</p>
<p>You should have used coloumb's law to explains why NaCl is stronger than FCl (hint, NaCl has smaller radius) :)</p>
<p>For the Carbon/Hydrogen one...the weight of both the Empircal and Molecular was 122, right?</p>
<p>I missed the AgCl/Ag2S thing, too! We did a qualitative analysis scheme in Chem this year but I completely forgot that AgCl was white... oh well :(</p>
<p>Dang, I thought that question was easy...but we do a lot of labs so maybe that is it.</p>