## Search found 50 matches

Wed Dec 09, 2020 6:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: wedge and dash
Replies: 14
Views: 97

### Re: wedge and dash

Alessia Renna 1D wrote:can someone explain the wedge and dash notation?

The dark wedge means it's coming towards you through the paper/screen and the dashed wedge means it's going away from you through the paper/screen. It is used to denote the three dimensionality of certain molecular shapes. Hope this helps!
Wed Dec 09, 2020 6:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw vs. trigonal pyramidal
Replies: 22
Views: 150

### Re: Seesaw vs. trigonal pyramidal

Are seesaw and trigonal pyramidal the same shape? I am confused Hi! No, seesaw and trigonal pyramidal are not the same shape. As aforementioned, seesaw has one lone pair and four bonding pairs while trigonal pyramidal has one lone pair and three bonding pairs. I have attached a picture of a table w...
Wed Dec 09, 2020 6:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 5
Views: 55

### Re: Bond Angles

I think I am missing something conceptual here, but why do bond angles, such as the 3 106 degree bond angles on SO3^2- , not add up to 360? If they are evenly spaced around the S atom wouldn't the angles need to add up to 360 degrees? Hi! The angles do not add up to 360º because the molecule is thr...
Wed Dec 09, 2020 6:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Shape
Replies: 10
Views: 111

### Re: Determining Shape

I had a similar question, and I just want to check my understanding. So electron geometry just takes into account areas of electron density while molecular shape takes into consideration whether those areas are an atom or a lone pair. Will we be asked to find electron geometry or molecular shape? Ho...
Wed Dec 09, 2020 5:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Formal charge when doing VSEPR
Replies: 2
Views: 23

### Re: Formal charge when doing VSEPR

When drawing lewis structures to determine molecular shape, do you typically also find the formal charge? Or is that not necessary in this case? To determine molecular shape, you typically start by drawing the Lewis structure. It may help to find the formal charge or check for resonance to ensure t...
Wed Dec 09, 2020 5:51 pm
Forum: Biological Examples
Topic: Final Exam
Replies: 8
Views: 126

### Re: Final Exam

So in one of the UA sessions the UA said that on his exam he was asked why Carbon monoxide was bad for the body, and in the question it asked for the heme complex to be drawn. I think that on our test it will be a little bit harder to ask for drawn examples, but I think that the question is still u...
Wed Dec 09, 2020 5:48 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling Week 9 HW Question 2
Replies: 11
Views: 111

### Re: Sapling Week 9 HW Question 2

Hi, Can anyone please explain how Ba[FeBr4]2 has a coordination number of 4? Hi! The coordination number refers to the number of bonds on the central atom. Seeing as there are four Br atoms bound to the central atom, Fe, the coordination number would be four. Keep in mind that when determining the ...
Wed Dec 09, 2020 5:45 pm
Forum: Naming
Topic: Naming quizlet
Replies: 41
Views: 269

### Re: Naming quizlet

Danielle Goldwirth 3F wrote:Thank you! Are we supposed to memorize all of these?

I'm not entirely sure, but I think I am going to just in case!
Wed Dec 09, 2020 5:43 pm
Forum: Student Social/Study Group
Topic: Final Exam
Replies: 11
Views: 115

### Re: Final Exam

Doing questions from the textbook was really helpful for me on the midterms. I definitely recommend!
Tue Dec 08, 2020 3:55 pm
Forum: Naming
Topic: common ligand names for final
Replies: 6
Views: 86

### Re: common ligand names for final

Which sheet are you referring to? Can someone help me find it? I believe they are referring to this PDF from Dr. Lavelle's website. https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/NamingCoordinationCompounds.pdf Thank you! Hopefully Dr. Lavelle will provide more insight on if we s...
Tue Nov 24, 2020 4:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape Names
Replies: 50
Views: 299

### Re: Shape Names

What is the shape called when there are 2 lone pairs and 2 bonding pairs like H2O? Is "bent" the official shape name? Hi! The official name would be bent or angular. An example of this would be H 2 O. Here is a link to a chart that I have found very helpful with learning the names of the ...
Tue Nov 24, 2020 4:48 pm
Forum: Hybridization
Topic: e density
Replies: 30
Views: 140

### Re: e density

asalest 2K wrote:is every bond and lone pair considered a region of electron density?

Hi! Yes, every bond and lone pair are considered a region of electron density. Every bond only counts as one area of electron density regardless of whether it is a single, double, or triple bond.

Hope that helps!
Tue Nov 24, 2020 4:46 pm
Forum: Hybridization
Topic: Lecture example ethene
Replies: 9
Views: 87

### Re: Lecture example ethene

The 2p and 2sp^2 orbitals a smaller energy gap between them than 2s and 2p because the 2sp^2 hybridized orbital is found in between the 2s and 2p orbitals. Atoms forms hybridized orbitals because it makes the resulting molecule more stable (lower potential energy) because it allows the regions of e...
Tue Nov 24, 2020 4:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: memorization
Replies: 12
Views: 121

### Re: memorization

I'm sure flashcards would also be very helpful! I'm planning on using the chart in the link to make flashcards as a study tool. There may be Quizlets available too!
Tue Nov 24, 2020 4:36 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Definition of diamagnetism and paramagnetism
Replies: 4
Views: 57

### Re: Definition of diamagnetism and paramagnetism

Tue Nov 24, 2020 4:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape vs. Electron Arrangement
Replies: 4
Views: 31

### Re: Shape vs. Electron Arrangement

I am a little bit confused about how to tell when we are supposed to give the shape of the electron arrangement of the molecule. Is there a "default"? I also get confused with whether we account for lone pairs when giving shape or electron arrangement. If anyone could help explain this, I...
Tue Nov 24, 2020 4:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: memorization
Replies: 12
Views: 121

### Re: memorization

Madison Wong 1G wrote:I use this as a reference for VSEPR and the shape/bond angles. Hope this helps!
https://ds055uzetaobb.cloudfront.net/im ... 091b2c.png

Thank you so much for the chart! It's so helpful!
Tue Nov 24, 2020 4:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #18, Week 7/8
Replies: 4
Views: 59

### Re: Sapling #18, Week 7/8

Hi! I also had a question about this problem. The last part refers to the hydrogen atoms being coplanar. How can you tell if atoms are coplanar or not? Thank you!
Tue Nov 24, 2020 4:14 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: What is bond order?
Replies: 8
Views: 108

### Re: What is bond order?

Just checking my understanding: bond order refers only to the number of bonds present and not to any actual chronological order or bonds (sounds silly, but that's what I originally inferred from the use of the word order haha). A single bond has a bond order of one, a double bond has a bond order of...
Tue Nov 24, 2020 3:27 pm
Forum: Hybridization
Topic: hybridization of phosphorus (Sapling Q.11)
Replies: 21
Views: 96

### Re: hybridization of phosphorus (Sapling Q.11)

Hi! This is another part of Sapling Q.11. I understood how your answers applied to the other diagram, but this diagram threw me for a loop. If any of you have advice on how to better understand and complete these questions it would be much appreciated! Thank you!
Tue Nov 24, 2020 3:20 pm
Forum: Hybridization
Topic: Hybridization techniques
Replies: 4
Views: 63

### Re: Hybridization techniques

Hi! I have also been having trouble grasping this concept beyond just memorization. In what context would we see hybridization of orbitals?

And thank you so much! I will be sure to watch that video (:
Wed Nov 11, 2020 12:30 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi bonds
Replies: 9
Views: 66

### Re: Sigma and Pi bonds

Hi! I don't recall this topic being mentioned in the lectures. Just confirming - we will not need to know this for the midterm next week? Thank you! I don't think Lavelle covered this in lectures yet either, so we won't have to know it. The midterm covers everything from the last eight bullets on o...
Wed Nov 11, 2020 12:27 pm
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds
Replies: 27
Views: 599

### Re: sigma and pi bonds

That is true! If you haven't seen this video, https://www.youtube.com/watch?v=pT8nrBrTOm4 you should check it out! It's actually really helpful. I look up videos on youtube for most topics! Hope this helps! This is so helpful! Thank you! I attached this example of identifying sigma and pi bonds whi...
Wed Nov 11, 2020 12:23 pm
Forum: Dipole Moments
Topic: Interactions Between Ions and Molecules
Replies: 7
Views: 57

### Re: Interactions Between Ions and Molecules

Hi! So just confirming my understanding: Ion--ion interactions are stronger because they have full negative and positive charges which attract each other. Other interactions are not as strong because the charges are only partial. Please let me know if this looks like a complete and accurate summatio...
Wed Nov 11, 2020 12:16 pm
Forum: Electronegativity
Topic: periodic table
Replies: 16
Views: 128

### Re: periodic table

Arnav Saud 3K wrote:For me, learning the trends was easiest with visual aids like this one.

This is so helpful! Thank you! (:
Wed Nov 11, 2020 12:10 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Ionic Structures
Replies: 6
Views: 35

### Re: Ionic Structures

Dr. Lavelle provides an excellent example of this toward the end of his lecture on 11/02/20 and he explains it further at the start of his lecture on 11/04/20. I was struggling with this topic as well, and I found it very helpful to rewatch this portion of the lectures after reading the explanations...
Wed Nov 11, 2020 11:53 am
Forum: Electronegativity
Topic: London Dispersion Forces
Replies: 9
Views: 87

### Re: London Dispersion Forces

Thank you so much everyone! Those are such helpful tips. I really appreciate it!
Wed Nov 11, 2020 11:48 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Can an Anion be Polarizing
Replies: 4
Views: 61

### Re: Can an Anion be Polarizing

I don't think so. A cation's positive charge is what causes it to be polarizing. Since a cation has a positive charge, the nucleus has a greater pull on the cation's electrons and they're held more tightly within the electron cloud. An anion has a negative charge, which means it has an excess of el...
Wed Nov 11, 2020 11:35 am
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi bonds
Replies: 9
Views: 66

### Re: Sigma and Pi bonds

I am not sure that he went into much detail about them last week. A single bond is a sigma bond. Double bond has one sigma, one pi. Triple has one sigma, 2 pi bonds. A sigma bond is stronger than a pi bond. Sigma bonds are overlapping of electrons on the end of each atom; it is a linear overlapping...
Wed Nov 11, 2020 11:34 am
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi bonds
Replies: 9
Views: 66

### Re: Sigma and Pi bonds

Hi! I don't recall this topic being mentioned in the lectures. Just confirming - we will not need to know this for the midterm next week? Thank you!
Wed Nov 11, 2020 11:27 am
Forum: Lewis Acids & Bases
Topic: Water
Replies: 62
Views: 492

### Re: Water

To provide a more technical and detailed answer: Water (H2O) is able to release a proton (H+) to form hydroxide ions. Water can also accept a proton to form hydronium (H3O+). Thus, water can act as both a Bronsted acid and a Bronsted base, making it amphoteric/amphiprotic. I found a diagram which a...
Tue Nov 10, 2020 5:27 pm
Forum: Resonance Structures
Topic: Oxidation Number
Replies: 9
Views: 56

### Re: Oxidation Number

Hi! I was also confused about what an oxidation number is and how to find it. Everyone's posts were very helpful. Just checking my understanding: An oxidation number is the amount of electrons that an atom gains or loses when forming a bond with another atom. There are set rules to assigning oxidati...
Tue Nov 10, 2020 5:20 pm
Forum: Electronegativity
Topic: Delta negative and delta positive?
Replies: 8
Views: 56

### Re: Delta negative and delta positive?

Hi! Putting a delta negative or a delta positive charge simply denotes the unequal sharing of electrons in the bond. The atom with the partial negative charge is pulling the electrons toward it, while the atom with the partial positive charge is farther from the electrons. I attached a diagram which...
Tue Nov 10, 2020 5:10 pm
Forum: Bond Lengths & Energies
Topic: bond length for different compounds
Replies: 3
Views: 24

### Re: bond length for different compounds

Hi! Thank you so much for that list it is so helpful. So just checking my understanding on your first point: Because larger atoms have more diffused orbitals, they form weaker bonds than smaller atoms. Is this true in all cases? For example, if two larger atoms were to be triple bonded while two sma...
Tue Nov 10, 2020 4:54 pm
Forum: Electronegativity
Topic: London Dispersion Forces
Replies: 9
Views: 87

### London Dispersion Forces

Hi! I am a little confused about London Dispersion Forces and how to identify them. I think #17 of the sapling homework is a really good example of this. The question is as follows: Which of the following exhibit only London Dispersion Forces? a. CH 4 b. BCl 3 c. NF 3 d. CH 3 F e. Br 2 I arrived at ...
Tue Nov 10, 2020 4:47 pm
Forum: Electronegativity
Topic: Sapling #15
Replies: 9
Views: 88

### Sapling #15

Hi! I am reviewing some of my Sapling answers, and I came across #10. The question is as follows: Which of these hydrogen halides is capable of hydrogen bonding when dissolved in water? a. HBr b. HF c. HCl d. HI I arrived at the answer b. HF, but I am not entirely sure of the reasoning behind this. ...
Tue Nov 10, 2020 4:43 pm
Forum: Electronegativity
Topic: Sapling HW Q13
Replies: 3
Views: 28

### Re: Sapling HW Q13

I was struggling with this question as well and your answer was so helpful! Thank you Crystal!

I really appreciate the drawing too. That made it so much clearer. (:
Tue Nov 10, 2020 4:37 pm
Forum: Dipole Moments
Topic: Sapling Q 19
Replies: 2
Views: 31

### Re: Sapling Q 19

Hey guys, so for this question we were given an SO2 bonding with an SO2. The answer key for this one described it as a dipole-dipole but called the molecule Hydrogen sulfide even though it's not. So would an SO2 interacting with an SO2 be considered a dipole dipole? The difference in electronegativ...
Thu Nov 05, 2020 2:51 pm
Forum: Ionic & Covalent Bonds
Topic: Sapling HW Week 5/6 #10
Replies: 5
Views: 29

### Sapling HW Week 5/6 #10

Hi! This question asks for us to organize the bonds in order from most ionic to most covalent. I know that the answer is as follows: Ionic K — F Ca — F Br — F Cl — F F — F Covalent (I hope the formatting for that comes through clearly) I am still a little unsure about why it is ordered the way it is...
Thu Nov 05, 2020 12:20 pm
Forum: Lewis Structures
Topic: Coordinate Covalent Bonds & Lewis Acid-base Reactions
Replies: 6
Views: 47

### Re: Coordinate Covalent Bonds & Lewis Acid-base Reactions

Hi! I just wanted to check my understanding of Lewis acids and bases. Lewis acids are molecules lacking electrons, and Lewis bases are electron rich molecules willing to provide electrons for acid-base bonding. Is this correct? Please feel free to correct me if I'm wrong! I'm still a little unsure o...
Thu Nov 05, 2020 11:59 am
Forum: Lewis Structures
Topic: Formal Charges
Replies: 7
Views: 51

### Re: Formal Charges

Hi! I am also a little confused on the concept of formal charges. This leads to my question of how to represent formal charges in the drawing on #2 in the Week 5/6 of the Sapling HW. If anyone knows how to do this please let me know! Thanks so much! Hi! I believe you are asking how to assign formal...
Thu Nov 05, 2020 11:53 am
Forum: Coordinate Covalent Bonds
Topic: Coordinate covalent bond
Replies: 3
Views: 38

### Re: Coordinate covalent bond

I was a little confused on this topic as well, so I appreciate your explanations! I found this short YouTube video to also be very helpful in clarifying what a coordinate covalent bond is and how they behave. Hope it helps!

Thu Nov 05, 2020 11:43 am
Forum: Resonance Structures
Topic: Resonance Lecture Question
Replies: 10
Views: 75

### Re: Resonance Lecture Question

Would you count the lone pair electrons individually or as a pair? For example, if there was a chlorine atom single bonded would that atom have L = 6 as in six individual electrons or L = 3 as in 3 pairs of electrons? Thanks for the clarification (: I believe that L would equal 6 :) Ok awesome! Tha...
Thu Nov 05, 2020 11:42 am
Forum: Lewis Structures
Topic: Formal Charge and Lewis Strucutre
Replies: 7
Views: 78

### Re: Formal Charge and Lewis Strucutre

Hi everyone! At the end of Monday's lecture Professor Lavelle used the example of the sulfate ion to demonstrate resonance and formal charge. He started by drawing the Lewis structure with each of the oxygens single bonded to the sulfur in the middle. I am confused as to why this model wouldn't wor...
Thu Nov 05, 2020 11:34 am
Forum: Lewis Structures
Topic: Formal Charges
Replies: 7
Views: 51

### Re: Formal Charges

Hi! I am also a little confused on the concept of formal charges.

This leads to my question of how to represent formal charges in the drawing on #2 in the Week 5/6 of the Sapling HW. If anyone knows how to do this please let me know! Thanks so much!
Thu Nov 05, 2020 11:17 am
Forum: Bond Lengths & Energies
Topic: Bond Length
Replies: 22
Views: 366

### Re: Bond Length

Hi! So bond length and bond strength are inversely related meaning that as the bond length increases, its strength decreases and vise-versa. I found this website which compares different examples of bonds (single, double triple) and their lengths and energy (see table 9.4). Hope you guys find this h...
Thu Nov 05, 2020 10:57 am
Forum: Resonance Structures
Topic: Resonance Lecture Question
Replies: 10
Views: 75

### Re: Resonance Lecture Question

Would you count the lone pair electrons individually or as a pair?

For example, if there was a chlorine atom single bonded would that atom have L = 6 as in six individual electrons or L = 3 as in 3 pairs of electrons?

Thanks for the clarification (:
Thu Nov 05, 2020 10:54 am
Forum: Octet Exceptions
Topic: Exceptions List
Replies: 4
Views: 72

### Re: Exceptions List

Thank you so much Anna! That is so helpful. I found this article which I thought might also be helpful. The illustrations are very clear!

https://www.thoughtco.com/exceptions-to ... ule-603993
Thu Nov 05, 2020 10:47 am
Forum: Properties of Light
Topic: Wavelength
Replies: 26
Views: 184

### Re: Wavelength

Hi! Does anyone have a good way to memorize the various wavelengths on the atomic spectrum?
Thu Nov 05, 2020 9:47 am
Forum: Lewis Structures
Topic: Formal Charge and Lewis Strucutre
Replies: 7
Views: 78

### Re: Formal Charge and Lewis Strucutre

Hi everyone! At the end of Monday's lecture Professor Lavelle used the example of the sulfate ion to demonstrate resonance and formal charge. He started by drawing the Lewis structure with each of the oxygens single bonded to the sulfur in the middle. I am confused as to why this model wouldn't work...