Search found 46 matches

by Alex Mele 2E
Tue Nov 24, 2020 4:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: memorization
Replies: 12
Views: 53

Re: memorization

The easiest way for me to think about shapes is just to draw a lewis diagram and picture the molecule in my head. Then I can see if it's a plane, pyramid, seesaw, etc. and think of the name that matches my mental image. Charts can also be helpful for memorizing what these possible names are!
by Alex Mele 2E
Tue Nov 24, 2020 4:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2 Scores
Replies: 9
Views: 56

Re: Midterm 2 Scores

I don't remember my TA saying when scores would come out, but I also heard from other student's that they might come out sometime today.
by Alex Mele 2E
Tue Nov 24, 2020 4:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 6
Views: 42

Re: Final

I don't think it's been addressed either, but I don't think there's any reason why we wouldn't have a lecture. At least if we learned new material on that Friday it would be fresh in our minds for the final.
by Alex Mele 2E
Tue Nov 24, 2020 12:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Focuse 2E.7
Replies: 2
Views: 15

Re: Focuse 2E.7

I think this question is asking you to look a the O-S-Cl bond angles and see if their measures are different from each other. In this trigonal pyramidal molecule, there is only one angle measure because every OSCl has equally spacing.
by Alex Mele 2E
Sun Nov 22, 2020 8:35 pm
Forum: Student Social/Study Group
Topic: Chem 14B with 20L
Replies: 5
Views: 62

Re: Chem 14B with 20L

Joel Meza 2E wrote:Is there no prerequisite for 20L that is a 20 series class? Or in other words, we don't have to previously taken a specific 20 series class to enroll in 20L?

Nope! 14A, 20A, and 20AH can each fulfill the prerequisite, and 14B, 20B, and 20BH can fulfill the corequisite.
by Alex Mele 2E
Tue Nov 17, 2020 3:09 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14BL and Chem 14B
Replies: 6
Views: 46

Re: Chem 14BL and Chem 14B

You can take them together or you can take 14BL after 14B. I don't think you can enroll in BL before enrolling in B.
by Alex Mele 2E
Mon Nov 16, 2020 1:29 pm
Forum: Student Social/Study Group
Topic: Pre-Med + Cluster Credits
Replies: 2
Views: 34

Pre-Med + Cluster Credits

Hi all! I recently looked at UCLA's recommended courses for medical school, and I noticed that lots of med schools require a year of English (or 3 quarters). I think any W class can count, so does anyone know if we need to take 2 more English/W classes after taking a cluster? Or does the cluster cou...
by Alex Mele 2E
Mon Nov 16, 2020 1:24 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cr and Cu as exceptions
Replies: 2
Views: 18

Re: Cr and Cu as exceptions

Mo does have 4d5 and 5s1. The half-filled d-orbital + half-filled s orbital is still a more stable combination than 4d4 5s2. This is the same rule that Cr follows even though Mo is one row down!
by Alex Mele 2E
Mon Nov 16, 2020 1:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape generalities
Replies: 4
Views: 20

Re: Molecular Shape generalities

Yes! As far as I know, any molecule with the same number of bonding and lone pairs will have the same VSEPR shape. Molecular geometry tables based one the VSEPR model assign shapes just based on those two factors.
by Alex Mele 2E
Mon Nov 16, 2020 1:15 pm
Forum: Dipole Moments
Topic: Bonds on MT2?
Replies: 1
Views: 26

Re: Bonds on MT2?

I recommend looking at the Chemical Bonds outline on Dr. Lavelle's website. It says we should understand ionic vs. covalent bonds, bond lengths, coordinate covalent bonds, dissociation energy, LD forces, dipole-dipole interactions, Hydrogen bonding, etc.
by Alex Mele 2E
Mon Nov 16, 2020 1:11 pm
Forum: Student Social/Study Group
Topic: Exercising Our Minds and Bodies
Replies: 84
Views: 245

Re: Exercising Our Minds and Bodies

I like to go for a walk in the morning to pick up a cup of coffee before class or to jog some hills on the weekends. I also participated in virtual yoga with my sorority on Saturday and it felt really good. :)
by Alex Mele 2E
Tue Nov 10, 2020 1:09 pm
Forum: Administrative Questions and Class Announcements
Topic: missing discussion
Replies: 4
Views: 38

Re: missing discussion

Your TA might let you attend another of their discussions for the week if you couldn't make the one you're enrolled in. That way you could still practice with the material.
by Alex Mele 2E
Mon Nov 09, 2020 8:45 pm
Forum: Student Social/Study Group
Topic: Chem 14B with 20L
Replies: 5
Views: 62

Chem 14B with 20L

Hi all! I was wondering if anyone else was planning on taking chem 14B and chem 20L together next quarter? Or if anyone has heard whether or not that's recommended?
by Alex Mele 2E
Mon Nov 09, 2020 8:42 pm
Forum: Student Social/Study Group
Topic: Step-Up vs. Drop-In Sessions
Replies: 7
Views: 37

Re: Step-Up vs. Drop-In Sessions

According to Dr. Lavelle's website, "Step-Up sessions go through step-by-step fundamentals working through prepared topics and worksheets for students who want step-by-step assistance. Drop-In sessions are for all students to ask questions and get involved in discussion. Workshops involve worki...
by Alex Mele 2E
Mon Nov 09, 2020 3:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 188
Views: 14294

Re: Advice from a Medical Student - Part II [ENDORSED]

Thank you for answering all of these questions! I always hear about how medical school is so hard to get into and it makes me feel good to hear from people who have done it. Do you know if a lot of your UCLA classmates got into programs too?
by Alex Mele 2E
Mon Nov 09, 2020 3:18 pm
Forum: Student Social/Study Group
Topic: Mid-quarter Check in
Replies: 67
Views: 207

Re: Mid-quarter Check in

Adjusting to the quarter system has been different. I feel like with all of my classes I'm always getting ready for a midterm or final! But I like that this class is structured with the same type of homework every week so I never feel like I'm forgetting something.
by Alex Mele 2E
Mon Nov 09, 2020 2:54 pm
Forum: Dipole Moments
Topic: Dipole confusion
Replies: 3
Views: 27

Re: Dipole confusion

Dipoles come from atoms with different electronegativity values. When one atom in a molecule attracts electrons more than another, it creates slightly positive and negative regions.
by Alex Mele 2E
Fri Nov 06, 2020 11:27 pm
Forum: Dipole Moments
Topic: Water and NaCl Solubility
Replies: 4
Views: 17

Re: Water and NaCl Solubility

In general, polar solvents dissolve polar solutes. Like others have said, the polarity of water is what separates a Na+ cation from a Cl- anion. Salts will dissolve in water because they are ionic and polar.
by Alex Mele 2E
Fri Nov 06, 2020 11:24 pm
Forum: Lewis Structures
Topic: Using sapling to draw lewis structures
Replies: 3
Views: 20

Re: Using sapling to draw lewis structures

What I did on sapling was click on the atom I wanted in the center then click in the answer box to set it down. I clicked on whatever bond I wanted to use then clicked on the central atom to attach them. Then, I replaced any incorrect atoms with the ones of the element I wanted. I clicked on single ...
by Alex Mele 2E
Fri Nov 06, 2020 11:18 pm
Forum: Lewis Structures
Topic: lewis structure
Replies: 17
Views: 44

Re: lewis structure

This notation shows the charge of the ion as a whole (not formal charge of each atom). You know to put + outside of the lewis structure of something with a net +1 charge, +2 for +2 charge, - for a -1 charge, and so on. You don't need to put a charge outside of brackets for a neutral atom.
by Alex Mele 2E
Fri Nov 06, 2020 11:15 pm
Forum: Student Social/Study Group
Topic: Studying From Home
Replies: 81
Views: 262

Re: Studying From Home

It's also helpful for me to have a designated study spot without many distractions. I like to have tea or coffee with me in a quiet spot and my phone in another room. It also helped me when studying for this midterm to make a checklist of everything I wanted to review. I listed lecture notes, textbo...
by Alex Mele 2E
Tue Nov 03, 2020 3:34 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Config Exceptions
Replies: 3
Views: 22

Re: Electron Config Exceptions

These exceptions occur because half- and fully filled d sublevels are more stable than other partially filled d sublevels. Electrons will generally want to be in the lowest (most stable) energy state, so for Cu or Cr they will fill up a d sublevel halfway or fully instead of the s sublevel.
by Alex Mele 2E
Tue Nov 03, 2020 3:27 pm
Forum: Lewis Structures
Topic: sides
Replies: 12
Views: 76

Re: sides

I don't think the sides matter either. For NO3, the actual 3d shape is trigonal planar with three 120 degree bond angles because of electron repulsion.
by Alex Mele 2E
Thu Oct 29, 2020 10:59 am
Forum: Einstein Equation
Topic: E=pv and E=pc
Replies: 6
Views: 71

Re: E=pv and E=pc

I don't know a lot about these either, but I know that they are saying E=mc^2 for objects moving at the speed of light.
by Alex Mele 2E
Thu Oct 29, 2020 10:49 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook Problem 1E.13 part a
Replies: 3
Views: 20

Re: Textbook Problem 1E.13 part a

This is the correct electron configuration for Ag. Because it's a transition metal, 5s1 is higher in energy than 4d10. So, the d orbital is completely filled with 10 electrons while the s orbital only has 1 electron. I hope this makes sense!
by Alex Mele 2E
Wed Oct 28, 2020 12:30 pm
Forum: Trends in The Periodic Table
Topic: Elements with a low ionization energy
Replies: 6
Views: 55

Re: Elements with a low ionization energy

I think that elements with a low ionization energy tend to form cations because it is relatively easy for them to lose an electron and therefore take on a positive charge.
by Alex Mele 2E
Wed Oct 28, 2020 12:00 pm
Forum: Trends in The Periodic Table
Topic: Size of isoelectronic atoms/ions
Replies: 9
Views: 48

Re: Size of isoelectronic atoms/ions

I don't think isoelectronic atoms/ions would have the same atomic radii, because they still have different numbers of protons and therefore different nuclear charges. A greater positive nuclear charge would pull its electrons in closer and create a smaller atomic radius.
by Alex Mele 2E
Wed Oct 28, 2020 11:56 am
Forum: General Science Questions
Topic: Midterm Grades
Replies: 30
Views: 282

Re: Midterm Grades

I think he said that partial credit will be awarded for some answer choices. I took that as partial credit for doing the necessary calculations and maybe picking an answer in the wrong final units, but I don't know for sure what type of answer could be worth partial credit.
by Alex Mele 2E
Wed Oct 28, 2020 11:47 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Probability Density
Replies: 3
Views: 53

Re: Probability Density

Hey Alex, Yea I think you're right. The probability of finding an electron in a specific point is a specific value associated with one location. You can think of probability density as a gradient where darker regions represent a greater probability density (you're more likely to find electrons ther...
by Alex Mele 2E
Fri Oct 23, 2020 8:38 pm
Forum: DeBroglie Equation
Topic: Practice Problem
Replies: 7
Views: 44

Re: Practice Problem

Did you convert from grams to kg before using the equation?
by Alex Mele 2E
Fri Oct 23, 2020 8:30 pm
Forum: Properties of Light
Topic: Emission/Absorption
Replies: 6
Views: 62

Re: Emission/Absorption

I think that the higher energy level might have to to be n2 and the lower n1, no matter which is the initial or final level. This would keep the frequency value positive, right?
by Alex Mele 2E
Fri Oct 23, 2020 7:13 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Spin States
Replies: 4
Views: 31

Re: Spin States

In my high school chem classes, we said that the first electron to enter an orbital had the +1/2 spin, and that the second electron had the negative spin. However, I don't know if this was just to keep things simple. All I know for sure is that the two electrons in an orbital must have opposite spins!
by Alex Mele 2E
Fri Oct 23, 2020 6:57 pm
Forum: Properties of Electrons
Topic: sapling homework question 6
Replies: 3
Views: 16

Re: sapling homework question 6

Hi! For this question, I used the Rydberg equation (v= R(1/n1^2)-(1/n2^2)) to find the frequencies between levels 6 and 1 and levels 6 and 5. For n=6 to n=1, the frequency is (3.29x10^15)(1^(-2) - 6^(-2) = 3.20x10^15 Hz. Using the same equation, I found that the frequency of the n=6 to n=5 transitio...
by Alex Mele 2E
Wed Oct 21, 2020 1:22 pm
Forum: Significant Figures
Topic: How would you round these numbers
Replies: 10
Views: 82

Re: How would you round these numbers

Your numbers are correct! For more information about rounding and sig figs in general, the link on Dr. Lavelle's website is short and really helpful. https://lavelle.chem.ucla.edu/wp-conten ... OUT_SF.pdf
by Alex Mele 2E
Wed Oct 21, 2020 1:14 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Probability Density
Replies: 3
Views: 53

Probability Density

Hi Chemistry community! While watching the lecture today I was wondering, what is the difference between probability density and probability of finding an electron somewhere? Is probability density just the function for probability at any given point?
by Alex Mele 2E
Tue Oct 13, 2020 5:20 pm
Forum: SI Units, Unit Conversions
Topic: Metric Conversions
Replies: 9
Views: 109

Re: Metric Conversions

Slightly different from the first answer, but my high school chem teacher taught us "King Henry Died by Drinking Chocolate Milk"
to remember Kilo, Hecto, Deca, (base unit), Deci, Centi, Milli.
by Alex Mele 2E
Tue Oct 13, 2020 2:59 pm
Forum: Limiting Reactant Calculations
Topic: Difference between limiting reactant and limiting reagent?
Replies: 14
Views: 77

Re: Difference between limiting reactant and limiting reagent?

These can usually be used interchangeably in questions, like others have said. However, the definitions of reactant and reagent aren't exactly the same. If this makes sense, a reagent is a chemical in a lab that is used in a reaction, while a reactant is specifically an active one in a reaction that...
by Alex Mele 2E
Tue Oct 13, 2020 2:22 pm
Forum: Properties of Light
Topic: Relationship Between Wavelength and Energy
Replies: 4
Views: 22

Re: Relationship Between Wavelength and Energy

Yes, energy is inversely proportional to wavelength. Energy is equal to frequency times Planck's constant, and wavelength is inversely related to frequency.
by Alex Mele 2E
Tue Oct 13, 2020 2:14 pm
Forum: Properties of Light
Topic: Memorizing Wavelengths
Replies: 10
Views: 59

Re: Memorizing Wavelengths

I also think we should have an idea of where things are on the spectrum, but I don't actually know if we need to memorize every specific wavelength. The relative wavelengths and frequencies of some forms of radiation were on the week 2 sapling homework though, so I think they're good to know, and we...
by Alex Mele 2E
Mon Oct 12, 2020 4:27 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Net moles produced
Replies: 3
Views: 26

Re: Net moles produced

For this equation, you can see that there are 30 moles on the reactant side (4 C4H10 and 26 O2) and 36 moles on the product side (16 CO2 and 20 H20). This means that 36-30=6 moles are created by the rearrangement of atoms in this reaction. For a different problem, you might also have to consider bal...
by Alex Mele 2E
Fri Oct 09, 2020 9:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Petition to Bring Music Back To Lectures [ENDORSED]
Replies: 34
Views: 527

Re: Petition to Bring Music Back To Lectures [ENDORSED]

Hahaha, I agree! I love the intro music in these lectures.
by Alex Mele 2E
Fri Oct 09, 2020 1:34 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: HW Problem E.9
Replies: 7
Views: 89

Re: HW Problem E.9

This was really helpful, thank you!![/quote]

No problem! :)
by Alex Mele 2E
Fri Oct 09, 2020 1:32 pm
Forum: Administrative Questions and Class Announcements
Topic: Accessing the E-textbook [ENDORSED]
Replies: 58
Views: 6345

Re: Accessing the E-textbook [ENDORSED]

I am slightly confused as to why people are saying sapling isn't mandetory?? It most certainly is. Sapling is where we submit our homework assignments which make up 50pts of our final grade. I wonder if Sapling was just optional for previous classes, because our syllabus definitely says that it's m...
by Alex Mele 2E
Wed Oct 07, 2020 5:30 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: HW Problem E.9
Replies: 7
Views: 89

Re: HW Problem E.9

Hi Cady! You can look at the periodic table to see that the ion of Mg has a charge of +2 because of its 2 valence electrons, and the polyatomic ion sulfate is SO4 with a charge of -2. This means that MgSO4 is magnesium sulfate. Magnesium sulfate heptahydrate is MgSO4 plus 7H2O because hydrate repres...
by Alex Mele 2E
Wed Oct 07, 2020 5:21 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 200
Views: 141256

Re: Rusty on High School Chem [ENDORSED]

I'm a first-year UCLA student, and I took AP Chemistry as a junior in high school. One way I've been keeping the material fresh in my memory has been by tutoring other current high school students! Coming into Chem 14A, I found that the Audio-Visual Focus Topics were also very useful as their prelim...
by Alex Mele 2E
Wed Oct 07, 2020 5:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 221
Views: 116119

Re: Advice from a Medical Student [ENDORSED]

This is such great advice! I am a first-year pre-med student taking Chem 14A and I think hearing from others who have been in my position is super helpful.

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