Step Up Session Worksheet (Monday + Friday, Hannah) [ENDORSED]

[Chem_Mod]

Hi everyone! I'm Hannah Chew, and I'm hosting UA Step Up sessions on Friday 1-2pm and Monday 11-12pm.
If you plan on attending, please have this worksheet loaded onto your phone or laptop! We'll be working through the questions, step by step, in Young Hall 1290-2. I'll post the worksheets ahead of time, but if you cannot make it to the session, I'll post the answer key + shown work, too. Be sure to check the dates on the worksheet:) All worksheets will be posted on this same thread every week.

See you all soon!

[MichaelMoreno2G]

Will your sessions be every Friday and Monday for the rest of the quarter? Or just for this week?

[Chem_Mod]

Will your sessions be every Friday and Monday for the rest of the quarter? Or just for this week?

My Step Up Sessions are every Friday and the following Monday. We'll be going over the same worksheet for both sessions, so come to either one!

[Chem_Mod]

Here is the answer key for Week 2 Topics Step Up Worksheet!

[Chem_Mod]

Week 3 Topics Step Up Worksheet for October 19 and October 22

[MichaelMoreno2G]

Here is the answer key for Week 2 Topics Step Up Worksheet!

Honestly, thank you so much for these. I feel like this is really good review for me as I tend to learn more from seeing how a problem is actually done. I look forward to attending one of your step up sessions.

[Chem_Mod]

Here is the answer key for Week 3 Topics Worksheet!

[Chem_Mod]

Week 4 Topics Worksheet for Step Up (10/26, 10/29)

[Kenan Kherallah 2C]

Thank you so much for the extra practice!

[Chem_Mod]

Here is the key for Week 4 Topics Step Up Worksheet.

[Chem_Mod]

Here is the Week 5 Topics Step Up Worksheet for 11/2 and 11/5. We will be going over Lewis structures for the most part, but I'll save some time at the end for any questions about the midterm! -Hannah

[Chem_Mod]

Here is last week's answer key.

[Chem_Mod]

I've attached the Week 6 Topics Step Up Worksheet for Friday (11/9). NOTE: Monday's Step Up Session (11/12) is cancelled due to Veterans Day.

[Chem_Mod]

Here is the Week 6 Topics Key.

EDIT: Correction, there is no hydrogen bonding in 3D.

[Chem_Mod]

Here is the worksheet for tomorrow's step up session!

[504999383]

Thank you for the extra practice!!

[Kenan Kherallah 2C]

Can someone explain how to draw KrF4

[ariana_apopei1K]

Can someone explain how to draw KrF4

You put Kr as the central atom and arrange F around it, then count that there are 36 total e- to use. Subtract 4 single bonds, giving you 28 e. Once you give all the F their octet, you're left with 4 extra e-. Fluorine does not allow for expanded octets, so the remaining four e- get put onto the Kr as two lone pairs. The VSEPR formula for it is AX4E2. Hope that helps!

[504999383]

Will your step up session be on new material or the topics for test #3?

[Chem_Mod]

Here is the key for Week 7, sorry for the delay! There was no worksheet for Week 8.

[Chem_Mod]

Will your step up session be on new material or the topics for test #3?

November 30 (Friday) will cover new topics.

[Jordan Lo 2A]

Thank you!

[annabel 2A]

On the Week 6 Worksheet #4a [Rank the following from weakest intermolecular forces to strongest a) H2S, H2Te, H2Se] why is the strength of london dispersion forces more important than the dipole-dipole forces? Doesn't H2S have the strongest dipole-dipole forces of the three molecules?

[Chem_Mod]

All of the elements are in the same column and have relatively similar electronegativities (you can also look up a chart to confirm), but the biggest difference is the atomic size of the central atom. Size has to do with london dispersion forces.

[Chem_Mod]

Here is the worksheet for tomorrow (11/30) and Monday (12/3).

[Joussie Camacho 4I]

On the Week 6 Step-Up, why is #1a. only dipole-dipole and dispersion forces? Isn't there hydrogen bonding also between the hydrogen of one CH3CF3 and the fluorine of another CH3CF3 molecule?

[ariana_apopei1K]

On the Week 6 Step-Up, why is #1a. only dipole-dipole and dispersion forces? Isn't there hydrogen bonding also between the hydrogen of one CH3CF3 and the fluorine of another CH3CF3 molecule?

No, the H in the individual molecule must have hydrogen bonded to N, O, or F first for the interaction youre describing to happen. So for water for example, the H and O have the strong attraction because of the high difference in electronegativity, and another water molecule would then be attracted to it to make hydrogen bonds. But if the molecules as individuals dont have H bonded to N O or F then no hydrogen bonding will occur between multiple molecules. hope that made sense

[Joussie Camacho 4I]

On the Week 6 Step-Up, why is #1a. only dipole-dipole and dispersion forces? Isn't there hydrogen bonding also between the hydrogen of one CH3CF3 and the fluorine of another CH3CF3 molecule?

No, the H in the individual molecule must have hydrogen bonded to N, O, or F first for the interaction youre describing to happen. So for water for example, the H and O have the strong attraction because of the high difference in electronegativity, and another water molecule would then be attracted to it to make hydrogen bonds. But if the molecules as individuals dont have H bonded to N O or F then no hydrogen bonding will occur between multiple molecules. hope that made sense

Got it! Makes perfect sense, thank you!

[Joussie Camacho 4I]

You said that in order for hydrogen bonding to occur, the hydrogen in the individual molecule has to be bound to either O,N, or F to hydrogen bond with another molecule, but in CH3CH2OCH2CH3, none of the hydrogens are actually bound to the oxygen, but in number 3 d. of this worksheet, it says that CH3CH2OCH2CH3 can hydrogen bond with another molecule of the same species. I'm assuming that's because the partially positive hydrogen of one molecule hydrogen bonds to the partially negatively charged oxygen of another molecule. I'm just confused because I thought that in order for any hydrogen bonding to occur, there had to be a hydrogen bond within the original molecule, which in this case there isn't.

[ariana_apopei1K]

You said that in order for hydrogen bonding to occur, the hydrogen in the individual molecule has to be bound to either O,N, or F to hydrogen bond with another molecule, but in CH3CH2OCH2CH3, none of the hydrogens are actually bound to the oxygen, but in number 3 d. of this worksheet, it says that CH3CH2OCH2CH3 can hydrogen bond with another molecule of the same species. I'm assuming that's because the partially positive hydrogen of one molecule hydrogen bonds to the partially negatively charged oxygen of another molecule. I'm just confused because I thought that in order for any hydrogen bonding to occur, there had to be a hydrogen bond within the original molecule, which in this case there isn't.

omg my bad! I keep thinking H bonds happen within the molecule itself but they're interactions between molecules. But I also don't understand why 3d is yes, i was using my notes from the session and i wrote that they can't occur

[ariana_apopei1K]

You said that in order for hydrogen bonding to occur, the hydrogen in the individual molecule has to be bound to either O,N, or F to hydrogen bond with another molecule, but in CH3CH2OCH2CH3, none of the hydrogens are actually bound to the oxygen, but in number 3 d. of this worksheet, it says that CH3CH2OCH2CH3 can hydrogen bond with another molecule of the same species. I'm assuming that's because the partially positive hydrogen of one molecule hydrogen bonds to the partially negatively charged oxygen of another molecule. I'm just confused because I thought that in order for any hydrogen bonding to occur, there had to be a hydrogen bond within the original molecule, which in this case there isn't.

omg my bad! I keep thinking H bonds happen within the molecule itself but they're interactions between molecules. But I also don't understand why 3d is yes, i was using my notes from the session and i wrote that they can't occur

I get that the O is slightly negative bu the H's in the same molecule don't have dipole moments with the C's? So the H's aren't slightly positive

[Joussie Camacho 4I]

You said that in order for hydrogen bonding to occur, the hydrogen in the individual molecule has to be bound to either O,N, or F to hydrogen bond with another molecule, but in CH3CH2OCH2CH3, none of the hydrogens are actually bound to the oxygen, but in number 3 d. of this worksheet, it says that CH3CH2OCH2CH3 can hydrogen bond with another molecule of the same species. I'm assuming that's because the partially positive hydrogen of one molecule hydrogen bonds to the partially negatively charged oxygen of another molecule. I'm just confused because I thought that in order for any hydrogen bonding to occur, there had to be a hydrogen bond within the original molecule, which in this case there isn't.

omg my bad! I keep thinking H bonds happen within the molecule itself but they're interactions between molecules. But I also don't understand why 3d is yes, i was using my notes from the session and i wrote that they can't occur

I get that the O is slightly negative bu the H's in the same molecule don't have dipole moments with the C's? So the H's aren't slightly positive

That's what I thought! So I'm assuming the best explanation is that technically carbon is slightly more electronegative than hydrogen (even though I would consider it negligible because carbon's electronegativity is 2.5 and hydrogen's is 2.2) so there ends us being a small dipole towards the C, making the hydrogen slightly positive and thus able to bond with the oxygen from another molecule, which we know has a partial negative charge because it's so electronegative.

[Chem_Mod]

You said that in order for hydrogen bonding to occur, the hydrogen in the individual molecule has to be bound to either O,N, or F to hydrogen bond with another molecule, but in CH3CH2OCH2CH3, none of the hydrogens are actually bound to the oxygen, but in number 3 d. of this worksheet, it says that CH3CH2OCH2CH3 can hydrogen bond with another molecule of the same species. I'm assuming that's because the partially positive hydrogen of one molecule hydrogen bonds to the partially negatively charged oxygen of another molecule. I'm just confused because I thought that in order for any hydrogen bonding to occur, there had to be a hydrogen bond within the original molecule, which in this case there isn't.

Hi Joussie, you're correct. There is no hydrogen bonding between two molecules of CH3CH2OCH2CH3. I corrected it during the step up session, but I forgot to update the key. Sorry about the confusion!

[Chem_Mod]

Here is the worksheet key for Week 9 Topics.

Corrections about what I discussed:
- I mistakenly said that a square planar coordination compound has two lone pair of electrons while a tetrahedral coordination compound does not. This rule can only be applied to non-d block elements (ie "normal" VESPR) rules. For coordination compounds with a coordination number of 4, either tetrahedral or square planar is an acceptable answer.
- Use bis, tris, tetrakis to indicate the number of polydentate ligands, not the number of binding sites.

Sorry for the confusion!

[Joussie Camacho 4I]

You said that in order for hydrogen bonding to occur, the hydrogen in the individual molecule has to be bound to either O,N, or F to hydrogen bond with another molecule, but in CH3CH2OCH2CH3, none of the hydrogens are actually bound to the oxygen, but in number 3 d. of this worksheet, it says that CH3CH2OCH2CH3 can hydrogen bond with another molecule of the same species. I'm assuming that's because the partially positive hydrogen of one molecule hydrogen bonds to the partially negatively charged oxygen of another molecule. I'm just confused because I thought that in order for any hydrogen bonding to occur, there had to be a hydrogen bond within the original molecule, which in this case there isn't.

Hi Joussie, you're correct. There is no hydrogen bonding between two molecules of CH3CH2OCH2CH3. I corrected it during the step up session, but I forgot to update the key. Sorry about the confusion!

No worries, thank you! So, just to clarify, there does have to be a hydrogen bond within the molecule AND a hydrogen from one molecule has to be able to hydrogen bond with a F, O, or N on another molecule of the same species?

[Chem_Mod]

Yes, you are correct. We need H-X (where X = N, O, F) on one molecule because this allows H to have a partial positive charge due to the high electronegativity of N, O, or F. We need another molecule to have X so that there's a partial negative charge on that atom. These partial charges attract each other to form a Hydrogen bond between H on one molecule and X on the other.

[Chem_Mod]

Last worksheet and Step Up Session of the quarter!

[Emilee Hosking 1D]

Can you please post the solutions to Step Up Week 10?