Search found 91 matches

by Faith Lee 2L
Mon Feb 22, 2021 4:46 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing vs Reducing
Replies: 39
Views: 83

Re: Oxidizing vs Reducing

I learned OIL RIG in high school, which works if you're looking for another way to remember the definitions of oxidation and reduction!

O - Oxidation
I - Is
L - Losing e-

R - Reduction
I - Is
G - Gaining e-
by Faith Lee 2L
Mon Feb 22, 2021 4:37 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Q and K
Replies: 35
Views: 66

Re: Q and K

Both Q and K refer to the ratio of products to reactants; the only difference is that K is the constant when the system is at equilibrium while Q can be used to describe a system at non-equilibrium states. Since systems want to reach equilibrium, we know that if Q < K, then there are too little prod...
by Faith Lee 2L
Mon Feb 22, 2021 4:34 pm
Forum: Ideal Gases
Topic: Chem BL
Replies: 89
Views: 388

Re: Chem BL

I'm taking 14BL and 14C next quarter! It's pretty common to take them together so while it might be difficult, it isn't unheard of :)
by Faith Lee 2L
Mon Feb 22, 2021 4:33 pm
Forum: Student Social/Study Group
Topic: Fave food
Replies: 92
Views: 188

Re: Fave food

I love sushi but my wallet doesn't :(
by Faith Lee 2L
Mon Feb 22, 2021 4:32 pm
Forum: Balancing Redox Reactions
Topic: "Leo" Oxidation Numbers
Replies: 23
Views: 58

Re: "Leo" Oxidation Numbers

In case we forget what oxidation and reduction means, LEO (losing electrons = oxidation) helps us remember that oxidation involves a loss of electrons. Naturally, then, reduction involves a gain of electrons :)
by Faith Lee 2L
Mon Feb 15, 2021 2:33 pm
Forum: Student Social/Study Group
Topic: Midterm 2 Nerves
Replies: 40
Views: 151

Re: Midterm 2 Nerves

Definitely nervous––and I'm sure there are very few people who aren't! I struggled with thermodynamics in high school and it's definitely one of my least favorite units in chemistry, but I think it's great that we have a lot of resources to practice with and ease some nerves. I would highly recommen...
by Faith Lee 2L
Mon Feb 15, 2021 2:31 pm
Forum: Student Social/Study Group
Topic: Fav Shows of the Moment
Replies: 98
Views: 216

Re: Fav Shows of the Moment

I'm watching New Girl! I usually stop watching shows after Season 2 or 3 because I find that the writing is super slow/draggy or the plot becomes repetitive, but I'm on Season 7 of New Girl––which is saying something. I highly recommend it; super lighthearted and funny and really easy to get into af...
by Faith Lee 2L
Mon Feb 15, 2021 2:28 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy definition
Replies: 27
Views: 73

Re: Entropy definition

Entropy (denoted S) is the level of disorder in a system :) It's also a state function, which means you can add/subtract entropy calculations!
by Faith Lee 2L
Mon Feb 15, 2021 2:27 pm
Forum: Administrative Questions and Class Announcements
Topic: MyUCLA Grade
Replies: 27
Views: 159

Re: MyUCLA Grade

I wouldn't worry about it too much! You can check your grades on CCLE as well and everything should be updated and fixed by the time grades are submitted :)
by Faith Lee 2L
Mon Feb 15, 2021 2:25 pm
Forum: Student Social/Study Group
Topic: Studying for Midterm 2
Replies: 45
Views: 180

Re: Studying for Midterm 2

When I do the homework problems, I put a star next to the ones I got wrong. That way, I can do more targeted practice on concepts I struggle with rather than try to focus equally on all sections. To study, I'll actually do the same problems multiple times (spread out over the course of the week so I...
by Faith Lee 2L
Tue Feb 09, 2021 4:59 pm
Forum: Calculating Work of Expansion
Topic: Work: Compression and Expansion
Replies: 6
Views: 26

Re: Work: Compression and Expansion

I want to mention in certain cases (like vacuums) expansion will not mean work has been done (you need the gas to be expanding against an opposing force, but a perfect vacuum does not have pressure)
by Faith Lee 2L
Tue Feb 09, 2021 4:57 pm
Forum: Student Social/Study Group
Topic: Test curve?
Replies: 24
Views: 116

Re: Test curve?

Given that 14A last quarter did not have a curve, I am pretty sure there isn't a curve for this class either.
by Faith Lee 2L
Tue Feb 09, 2021 4:56 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: delta H vs Delta S
Replies: 4
Views: 24

Re: delta H vs Delta S

Delta H refers to change in heat, while Delta S refers to change in entropy (the disorder or number of possible conditions).
by Faith Lee 2L
Tue Feb 09, 2021 4:54 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: ΔG° vs ΔG
Replies: 20
Views: 63

Re: ΔG° vs ΔG

I'm not sure if this is the best definition for our chemistry class, but in biology (ls7a) we learned that delta G naught (the one with the degree symbol) refers to standard (in other words, the delta G you would calculate under in a laboratory). Delta G does not (for example, it could be used to de...
by Faith Lee 2L
Tue Feb 09, 2021 4:52 pm
Forum: Ideal Gases
Topic: Chem BL
Replies: 89
Views: 388

Re: Chem BL

I'm planning to take Chem 14BL with Chem 14C next quarter! It's a pretty common path from what I've heard, so even if it is difficult you won't be alone :)
by Faith Lee 2L
Mon Feb 01, 2021 11:39 pm
Forum: Calculating Work of Expansion
Topic: different R constants
Replies: 7
Views: 23

Re: different R constants

You would have to reference the units in your problem (typically pressure). For example, R would equal 8.314 x 10^-2 when your units are L x bar /K x mol, but 62.364 when your units are L x Torr / K x mol :) Hope this helps!
by Faith Lee 2L
Mon Feb 01, 2021 11:36 pm
Forum: General Science Questions
Topic: Careless Mistakes
Replies: 54
Views: 231

Re: Careless Mistakes

I relate to this! It's so frustrating when you know how to solve something but still get it wrong by overlooking a mistake. I personally like to use the "ans" function on my calculator so that I can copy the exact value to my next calculation rather than having to type it again by hand (yo...
by Faith Lee 2L
Mon Feb 01, 2021 11:33 pm
Forum: Student Social/Study Group
Topic: Work Life Balance
Replies: 44
Views: 130

Re: Work Life Balance

I like to break up my exercise over the course of the day :) Going for a walk in the morning before my first class, running after lunch, and/or working out after dinner (each for short periods of time) makes it more manageable, especially on days when I have a lot to do or a lot of classes to attend...
by Faith Lee 2L
Mon Feb 01, 2021 11:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka2 << Ka1
Replies: 12
Views: 71

Re: Ka2 << Ka1

You can ignore Ka2 when it is significantly smaller than Ka1 (hence the double <<) :) The contribution that the second deprotonation makes towards the pH is negligible when added to the first.
by Faith Lee 2L
Mon Feb 01, 2021 11:26 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding a gas
Replies: 21
Views: 72

Re: Adding a gas

First, inert/noble gases do not react with the reactants nor the products. The way they affect pressure is important to note as well; there is no decrease in volume. With increased pressure as a result of decreasing volume, the concentrations of the reactants and products change (M = mol/V), causing...
by Faith Lee 2L
Mon Jan 25, 2021 9:38 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acid and Bases
Replies: 7
Views: 35

Re: Acid and Bases

For acidic solutions, there will be a higher concentration of hydronium ions compared to hydroxide :)
by Faith Lee 2L
Mon Jan 25, 2021 9:33 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: endo/exothermic reactions
Replies: 13
Views: 30

Re: endo/exothermic reactions

A transition from a solid to liquid, liquid to gas, or solid to gas requires a breaking of bonds and thus is an endothermic process (energy must be put into the system). Likewise, the transition from gas to liquid, liquid to solid, or gas to solid is an exothermic process because it releases energy ...
by Faith Lee 2L
Mon Jan 25, 2021 9:31 am
Forum: Student Social/Study Group
Topic: Exam Duration
Replies: 7
Views: 40

Re: Exam Duration

Since the test has to be taken during lecture (50 minutes), that's the time we will be allotted for the exam. However, most (if not all TAs) usually open their Zoom 10-15 minutes early so you can show them your periodic table/equation sheet and get yourself situated. I find it really helps to get th...
by Faith Lee 2L
Mon Jan 25, 2021 9:29 am
Forum: Phase Changes & Related Calculations
Topic: Sublimation
Replies: 13
Views: 43

Re: Sublimation

Since the formation of bonds is exothermic (as it releases energy and increases stability) and the breaking of bonds is endothermic (requires an input of energy), sublimation requires an input of energy to overcome the intermolecular forces holding each molecule to each other (and is thus endothermi...
by Faith Lee 2L
Mon Jan 25, 2021 9:26 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Water
Replies: 7
Views: 17

Re: Water

An important distinction to make is the difference between amphiprotic and amphoteric, because they are not the same thing (although they do sound similar): An amphiprotic substance is one that can act as a proton donor or acceptor (e.g., water), whereas an amphoteric substance is one that reacts wi...
by Faith Lee 2L
Mon Jan 18, 2021 3:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling Reset?
Replies: 17
Views: 94

Re: Sapling Reset?

I don't believe there is a reset button, but I like to write down the problems on a sheet of paper and then come back to them a couple hours later so that I've forgotten the solutions and/or past work I might have seen as I was writing the problem down :)
by Faith Lee 2L
Mon Jan 18, 2021 3:05 pm
Forum: Ideal Gases
Topic: reversing reactions
Replies: 83
Views: 437

Re: reversing reactions

The K for the reverse reaction is the inverse (1/K) of the forward reaction, and vice versa :)
by Faith Lee 2L
Mon Jan 18, 2021 3:04 pm
Forum: General Science Questions
Topic: class 1/18/21
Replies: 13
Views: 93

Re: class 1/18/21

There's nothing posted today! Enjoy your three-day weekend :)
by Faith Lee 2L
Mon Jan 18, 2021 3:03 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem Community and Sapling Grades
Replies: 25
Views: 95

Re: Chem Community and Sapling Grades

You can use the Grades tab on CCLE to check both your Chemistry Community and Sapling grades. Since they both take some time to update, you can always reference your post number (which can be found to the right of any post you make) or the Sapling website, which should indicate a percent score for y...
by Faith Lee 2L
Mon Jan 18, 2021 2:58 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: When would K be unchanged?
Replies: 31
Views: 93

Re: When would K be unchanged?

Things like concentration, pressure, volume, etc. can shift the reaction forwards or backwards, but does not change the K value (rather, the system is adjusting to reach K again). However, temperature (as mentioned above) can change K depending on whether or not heat is favorable for creating reacta...
by Faith Lee 2L
Mon Jan 11, 2021 11:44 pm
Forum: Student Social/Study Group
Topic: Comfort Movies
Replies: 128
Views: 341

Re: Comfort Movies

I love Disney's Fantasia 2000! My parents never really bought movies or took me to see them as a kid (we're just not a big movie family), so I would only have the same 3-5 movies to watch on repeat––this being one of them. Even though I've seen much better films since, this one has a special place i...
by Faith Lee 2L
Mon Jan 11, 2021 11:38 pm
Forum: Student Social/Study Group
Topic: Study Habits
Replies: 96
Views: 318

Re: Study Habits

I would avoid "passive" studying! I'm guilty of often rereading the textbook or highlighting my notes to study, and they've been proven to be highly ineffective. You can still reread and/or highlight, but make sure to do some other studying methods with them. I tried quizzing myself and so...
by Faith Lee 2L
Mon Jan 11, 2021 11:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1&2 Q9
Replies: 2
Views: 29

Re: Sapling Week 1&2 Q9

Benjamin's method works and is much more efficient than what I did, but you could alternatively set the 0.300 M as your NO "Initial Concentration" in your ice table. I set the initial concentrations of the other reactants as 0 M and the initial concentration of NO as 0.300 M (0.800 M - 0.5...
by Faith Lee 2L
Mon Jan 11, 2021 11:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Question about 14B Exams
Replies: 38
Views: 223

Re: Question about 14B Exams

That's correct! Our tests will be administered during our lecture times so that we have more time in discussion sections :)
by Faith Lee 2L
Mon Jan 11, 2021 11:29 pm
Forum: Administrative Questions and Class Announcements
Topic: Participation
Replies: 18
Views: 127

Re: Participation

As mentioned above, posts and responds both work! I didn't create a single "original post" in 14A last quarter and still received all 50 participation points through my responses :)
by Faith Lee 2L
Mon Jan 04, 2021 12:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Module 1A True/False question
Replies: 8
Views: 68

Re: Module 1A True/False question

a. Although the forward and reverse reactions are simultaneously occurring and reactants are changing into products and products are changing into reactants, these two reactions occur at the same rate. Therefore, the actual concentrations (and ratios/K) will not change. b. Although substances like c...
by Faith Lee 2L
Mon Jan 04, 2021 12:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constants
Replies: 15
Views: 191

Re: Equilibrium Constants

Yep! You need to balance the equation in order to correctly calculate K. If you do not have the correct stoichiometric coefficients, you will get an incorrect answer since you need to raise the concentrations to the power of their stoichiometric coefficient.
by Faith Lee 2L
Mon Jan 04, 2021 12:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Kc/Kp
Replies: 15
Views: 100

Re: K vs. Kc/Kp

Kc is defined by the molar concentrations of the products and reactants, while Kp is defined by the partial pressures of gases within a closed system. K is used as a broader, more generic equilibrium constant that can refer to either one :)
by Faith Lee 2L
Mon Jan 04, 2021 12:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: If K is large...
Replies: 11
Views: 81

Re: If K is large...

The K value represents a ratio of the equilibrium concentrations of the products over the equilibrium concentrations of the reactants. If there is a greater concentration of products at equilibrium, K > 1, and if there is a greater concentration of reactants at equilibrium, K < 1. For example, equat...
by Faith Lee 2L
Mon Jan 04, 2021 12:20 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem Community Username
Replies: 10
Views: 67

Re: Chem Community Username

You should be able to click your current alias in the upper right hand corner (next to notifications); then click User Control Profile :)
by Faith Lee 2L
Mon Dec 07, 2020 5:21 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: coord number and oxidation number
Replies: 3
Views: 52

Re: coord number and oxidation number

Oxidation number (as defined by the textbook) is the charge an atom would have if all the electrons in a bond were completely given to the more electronegative atom, rather than being equally/unequally shared. For example, the oxidation numbers in CH4 would be -4 for C and +1 for H. Coordination num...
by Faith Lee 2L
Mon Dec 07, 2020 5:16 pm
Forum: Student Social/Study Group
Topic: Plans for Relaxing After Finals
Replies: 98
Views: 558

Re: Plans for Relaxing After Finals

Looking forward to experiencing a (potential) rainy day! It almost never rains in SoCal and I've been waiting for a downpour for what seems like forever :)
by Faith Lee 2L
Mon Dec 07, 2020 5:14 pm
Forum: Administrative Questions and Class Announcements
Topic: final format
Replies: 5
Views: 71

Re: final format

I believe the exam will be 30 questions and 6 points each (with no partial credit) for a total of 180 points :)
by Faith Lee 2L
Mon Dec 07, 2020 5:13 pm
Forum: Bronsted Acids & Bases
Topic: Group 1 and 2 Cations
Replies: 3
Views: 43

Re: Group 1 and 2 Cations

Cations like Fe3+ have a high charge density and have greater "pulling" power over electrons, which weakens and eventually breaks the O--H bond in water (releasing H+). Group 1 and 2 cations don't have the same ability to break the O--H bond and therefore don't significantly change the pH.
by Faith Lee 2L
Mon Dec 07, 2020 5:11 pm
Forum: Student Social/Study Group
Topic: Curve
Replies: 29
Views: 220

Re: Curve

I don't recall any mention of a curve in lecture or the syllabus.
by Faith Lee 2L
Mon Nov 30, 2020 3:32 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 30
Views: 161

Re: Polarity

As long as the polar bonds within the molecule "cancel out," the overall molecule will be nonpolar. Imagine the non-central atoms all pulling on the electrons of the central atom with equal strength, or the central atom pulling on the electrons of the non-central atoms with equal strength,...
by Faith Lee 2L
Mon Nov 30, 2020 3:28 pm
Forum: Naming
Topic: Roman Numeral for Transition Metal
Replies: 7
Views: 104

Re: Roman Numeral for Transition Metal

The Roman numeral refers to the metal's oxidation number. When we calculate formal charge, we look at the charge an atom would have if the bonding were perfectly covalent in the sense that the atom had exactly a half-share in each pair of bonding electrons. Oxidation numbers work similarly, but assu...
by Faith Lee 2L
Mon Nov 30, 2020 3:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Finals Week
Replies: 12
Views: 183

Re: Finals Week

None of your finals should start until Week 11, so that you won't be learning any new material or be responsible for attending classes during your exams. For this class specifically, our final is Sunday, December 13 :)
by Faith Lee 2L
Mon Nov 30, 2020 3:20 pm
Forum: Hybridization
Topic: Pi Bonds break
Replies: 8
Views: 70

Re: Pi Bonds break

Pi bonds are characterized by their side-to-side overlap, which results in extreme rigidity. I don't know of any exceptions to the fact that attempting to move pi-bonded atoms independently of each other would cause the bond to break.
by Faith Lee 2L
Mon Nov 30, 2020 3:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Delocalized vs localized
Replies: 12
Views: 111

Re: Delocalized vs localized

Resonance is a blending of structures with the same arrangement of atoms, but different arrangements of electrons. Thus, the true structure of a molecule that has resonance is somewhere in between the different resonance structures; this means that the electrons are not "fixed" to a certai...
by Faith Lee 2L
Mon Nov 23, 2020 2:23 pm
Forum: Administrative Questions and Class Announcements
Topic: Thanksgiving Discussion
Replies: 7
Views: 62

Re: Thanksgiving Discussion

I don't think Dr. Lavelle has released any confirmation on Thanksgiving discussion plans, but I know that my other classes have canceled discussions and are actually prohibiting emails/contact during the entire break altogether. I would guess that our class would also cancel live meetings, but I'm s...
by Faith Lee 2L
Mon Nov 23, 2020 2:20 pm
Forum: Hybridization
Topic: Lack of Spin Pairing in Hybridized Orbitals
Replies: 2
Views: 48

Re: Lack of Spin Pairing in Hybridized Orbitals

Adding onto what Megan said, if we allowed spin pairing in the sp^2 orbitals, we would be left with 1 paired e- and 2 unpaired e- in the sp^2-orbital and no e- in the unhybridized p-orbital. This would only allow carbon to bond with 2 other atoms. By "moving" 1 of the e- in the paired sp^2...
by Faith Lee 2L
Mon Nov 23, 2020 2:15 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy
Replies: 19
Views: 168

Re: Ionization Energy

I also want to add that the order of removing electrons is not always the reversal of the order of adding electrons (especially in metals). For example, cobalt's electron configuration is [Ar]3d^74s^2, where the 4s^2 orbital fills before the 3^d. However, when we remove 2 electrons to make Co^2+, we...
by Faith Lee 2L
Mon Nov 23, 2020 2:11 pm
Forum: Hybridization
Topic: regions of electron density
Replies: 7
Views: 55

Re: regions of electron density

Adding onto the comments above me, you would count bonds and electron pairs as one region of electron density each. For example, it does not matter whether a bond is a single, double, or triple bond; all of them count as a single region of electron density. Likewise, a single unpaired electron (like...
by Faith Lee 2L
Mon Nov 23, 2020 2:03 pm
Forum: Ionic & Covalent Bonds
Topic: C-H bond polarity
Replies: 10
Views: 90

Re: C-H bond polarity

In general, we assume that any bond containing atoms with an electronegativity difference of less than 1.5 to be polar. However, when the difference is particularly small (anywhere from 0.0 to 0.4-0.5, depending on your source), we would describe the bond as nonpolar. You would need to refer to an e...
by Faith Lee 2L
Mon Nov 16, 2020 12:47 pm
Forum: Student Social/Study Group
Topic: Test Anxiety
Replies: 62
Views: 355

Re: Test Anxiety

I get test anxiety too! I literally threw up during one of my AP tests my junior year of HS, even though I had already had experienced multiple the year before and had been completely fine. I like to take deep breaths to clear my head and the "buzzing" that can sometimes happen in my ears....
by Faith Lee 2L
Mon Nov 16, 2020 12:43 pm
Forum: Lewis Structures
Topic: Lewis acids and bases
Replies: 23
Views: 128

Re: Lewis acids and bases

If you need a way to remember them, I think of acids as electron acceptors (both start with the letter "a"). On the other hand, bases are electron donators (a lowercase "b" is a lowercase "d," but flipped!).
by Faith Lee 2L
Mon Nov 16, 2020 12:38 pm
Forum: Student Social/Study Group
Topic: Favorite TV shows
Replies: 189
Views: 1204

Re: Favorite TV shows

Criminal Minds, Black Mirror, and All American are some of my favorites! If you're looking for a laugh/lighter show, I would recommend The Good Place or The Office :)
by Faith Lee 2L
Mon Nov 16, 2020 12:35 pm
Forum: Bond Lengths & Energies
Topic: LDF Bond Strength
Replies: 11
Views: 116

Re: LDF Bond Strength

Adding onto what Ben said, I think you might be thinking of intramolecular forces, where the bond strength/length really would matter. However, LDF occurs between molecules, not within them, making them an intermolecular force. In this case, a greater number of electrons would allow for greater attr...
by Faith Lee 2L
Mon Nov 16, 2020 12:33 pm
Forum: Student Social/Study Group
Topic: Exercising Our Minds and Bodies
Replies: 105
Views: 578

Re: Exercising Our Minds and Bodies

I usually go for a run to get my body moving :) I would really recommend using Google Maps to chart your own custom route beforehand, and then go out and run it! I've been able to discover a lot of hidden trails/destinations this way, and it makes you feel like you're on an adventure lol
by Faith Lee 2L
Tue Nov 10, 2020 12:29 am
Forum: Octet Exceptions
Topic: Expanded Octets
Replies: 3
Views: 56

Re: Expanded Octets

I agree with what is written above! As long as an element has the "room" for an expanded octet, it can theoretically accept additional electrons.
by Faith Lee 2L
Tue Nov 10, 2020 12:27 am
Forum: Student Social/Study Group
Topic: Studying From Home
Replies: 91
Views: 567

Re: Studying From Home

Not sure if anyone has mentioned this, but the Pomodoro Technique works really well for me! You set a timer on your phone and study for 25 minutes, and then take a 5 minute break (during which you can grab a snack, walk around, or stretch; anything except using electronic devices is recommended). Th...
by Faith Lee 2L
Tue Nov 10, 2020 12:21 am
Forum: Ionic & Covalent Bonds
Topic: Ionic/Covalent
Replies: 8
Views: 43

Re: Ionic/Covalent

Here are some examples, if it would help to see it written this way :) Example of a covalent bond exhibiting ionic character: 1. e- pairs in covalent bonds may not be equally shared 2. The more electronegative atom will be closer to the e- pair, and is slightly negative (delta-) 3. The other atom is...
by Faith Lee 2L
Tue Nov 10, 2020 12:12 am
Forum: Ionic & Covalent Bonds
Topic: delta + or -
Replies: 12
Views: 97

Re: delta + or -

To add on to everyone's informative posts: Something Dr. Lavelle mentioned in his lecture today was this relationship: Increasing difference in electronegativity → Increasing difference in charge (delta- and delta+) → Increasing ionic character of the covalent bond. Because O has a greater electrone...
by Faith Lee 2L
Tue Nov 10, 2020 12:05 am
Forum: Student Social/Study Group
Topic: grade worries
Replies: 110
Views: 1217

Re: grade worries

I've been worried about my grades after the midterm too, especially since the True/False questions are worth a lot of points but don't offer the same forgiveness as the Calculation questions (where you can receive partial credit). I set up a grade calculator for myself, which helps me feel like I ha...
by Faith Lee 2L
Mon Nov 02, 2020 6:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14B Enrollment
Replies: 27
Views: 348

Re: Chem 14B Enrollment

Like a couple people mentioned, I think the answer really depends on how your other classes are going to look like. If you're looking to get a specific lecture/discussion time, first pass would be a smart choice. I think it's really amazing that Dr. Lavelle lets in everyone on the waitlist, but I do...
by Faith Lee 2L
Mon Nov 02, 2020 6:48 pm
Forum: Resonance Structures
Topic: True Double / Single Bonds
Replies: 3
Views: 45

Re: True Double / Single Bonds

"True" bonds are bonds that do not exhibit resonance. For example, a regular single bond has a length of about 1.40 angstroms while a double bond has a length of about 1.20 angstroms. However, certain molecules are more stable when they have a resonance hybrid structure. In other words, so...
by Faith Lee 2L
Mon Nov 02, 2020 6:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Fall 2020 Midterm 1 Instructions
Replies: 20
Views: 1087

Re: Fall 2020 Midterm 1 Instructions

I've heard from other students who attended Dr. Lavelle's office hours today that exam scores will be up on Thursday :)
by Faith Lee 2L
Mon Nov 02, 2020 6:41 pm
Forum: SI Units, Unit Conversions
Topic: Using a Calculator
Replies: 10
Views: 86

Re: Using a Calculator

I want to add that for most calculators, you can scroll up to previous calculations and click "enter" for your calculator to bring up a certain value. It's really helpful for empirical formula problems where you calculate the mole value for multiple elements and then have to go back and di...
by Faith Lee 2L
Mon Nov 02, 2020 6:36 pm
Forum: Student Social/Study Group
Topic: Halloween!!!
Replies: 54
Views: 349

Re: Halloween!!!

I'm a little late to this thread but I watched a movie and had Chipotle because they had a BOGO deal over the weekend! I recommend keeping eyes peeled for holiday deals like these around this time of year :)
by Faith Lee 2L
Mon Oct 26, 2020 11:54 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1376

Re: How are you studying?

Watching the audio-visual focus topics really helped me! They're a great supplement to Dr. Lavelle's videos, and I find that the post-module assessments help me 1. identify concepts I'm weaker in, and 2. confirm my understanding in concepts I have more experience with :)
by Faith Lee 2L
Mon Oct 26, 2020 11:51 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 1 Scores
Replies: 2
Views: 77

Re: Midterm 1 Scores

You'll have to ask Dr. Lavelle or a TA if you want an official answer, but I agree with Melody; it's more likely that results will be released after everyone has taken it so that later discussion groups don't have an unfair advantage.
by Faith Lee 2L
Mon Oct 26, 2020 11:46 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr Frequency Formula Question
Replies: 2
Views: 37

Re: Bohr Frequency Formula Question

I think of n1 and n2 as E(final) and E(initial), and it helps me keep track of them more easily :) You want to remember that Delta E (change in energy) is E(final) - E(initial), so you should always start with the lower energy level (assuming that you are doing an emission problem). Another way to c...
by Faith Lee 2L
Mon Oct 26, 2020 12:44 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Rule Names
Replies: 3
Views: 27

Re: Rule Names

Like Janelle and Margaret mentioned, I think it's much more important to understand the concepts behind each principle and their purpose (to ensure that we are writing each electron configuration so that they will have the lowest possible energy). However, I don't think it would hurt to memorize the...
by Faith Lee 2L
Mon Oct 26, 2020 12:41 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Subshell Definition
Replies: 9
Views: 60

Re: Subshell Definition

Hi! A subshell is another name for the angular momentum (l), while an orbital is the magnetic quantum number (ml). I use this diagram to help me remember and visualize the difference--I find it confusing too!
by Faith Lee 2L
Wed Oct 21, 2020 2:11 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Diagram from Lecture
Replies: 5
Views: 56

Re: Heisenberg Diagram from Lecture

Like Brian, Apurva, and Lucy mentioned, you would need both detectors to identify distance and time (which would then give you velocity). Dr. Lavelle's diagram really helps understand this relationship, but I couldn't find a similar diagram online so I drew a picture modeling his. I've attached it b...
by Faith Lee 2L
Wed Oct 21, 2020 2:05 pm
Forum: Balancing Chemical Reactions
Topic: H7
Replies: 4
Views: 54

Re: H7

Like Inderpal mentioned, I would check with your TA. However, if you are looking to memorize the most common ones, this is a really helpful sheet you can use to memorize them :)
by Faith Lee 2L
Tue Oct 20, 2020 3:35 pm
Forum: Properties of Electrons
Topic: Slide from Monday 10/21 Lecture
Replies: 4
Views: 51

Re: Slide from Monday 10/21 Lecture

Here are my notes as well! Hope this helps :)
by Faith Lee 2L
Mon Oct 19, 2020 3:49 pm
Forum: Properties of Electrons
Topic: Possible energy levels for electrons
Replies: 5
Views: 47

Re: Possible energy levels for electrons

I believe it would go completely unabsorbed; this is why spectral lines do not include every wavelength and energy is absorbed/emitted in discrete "packets," or quanta. The energy of the electron must exactly match the energy difference between two principal energy levels :)
by Faith Lee 2L
Mon Oct 19, 2020 3:44 pm
Forum: Significant Figures
Topic: Sig Figs
Replies: 12
Views: 124

Re: Sig Figs

As a general rule of thumb, it's best to use the same amount of significant figures that are given in the problem :) If our midterm is entirely multiple choice, I don't think you'll have to worry about them too much but it doesn't hurt to get them down for future FRQs or general knowledge :)
by Faith Lee 2L
Thu Oct 15, 2020 1:37 pm
Forum: Student Social/Study Group
Topic: iPad vs Paper notes
Replies: 32
Views: 397

Re: iPad vs Paper notes

I worked a couple jobs throughout the last few years and saved up for an iPad, but whether it's worth the money would really depend on how you like to take notes/learn information. Personally, I like to use my iPad for my homework or for annotating lecture slides in my classes, but I find it ineffic...
by Faith Lee 2L
Thu Oct 15, 2020 1:27 pm
Forum: Limiting Reactant Calculations
Topic: M.7 Limiting Reactant
Replies: 4
Views: 72

Re: M.7 Limiting Reactant

I believe you are correct that the limiting reactant if the magnesium, and you would have to use the moles of Mg and convert it to moles of B using the mole ratio. I've attached my work below in case it would help to see it written out!

by Faith Lee 2L
Wed Oct 14, 2020 5:00 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 6
Views: 45

Re: Work Function

I believe so! It's also referred to as the threshold energy :)
by Faith Lee 2L
Tue Oct 13, 2020 10:03 am
Forum: Limiting Reactant Calculations
Topic: M11 Part C
Replies: 2
Views: 45

Re: M11 Part C

Since oxygen is the limiting reactant, we have to use oxygen to determine the amount of P4O6 that can be created. I converted the remaining moles of oxygen from the previous reactions into moles of P4O6 using the mole ratio and then converted moles of P4O6 into grams. I've attached my work below in ...
by Faith Lee 2L
Tue Oct 13, 2020 9:57 am
Forum: Balancing Chemical Reactions
Topic: Mixed Numbers
Replies: 7
Views: 91

Re: Mixed Numbers

I agree with Sid Panda 2A, but note that you can have mixed numbers in your balanced equation if the question asks you for a specific quantity of a certain compound. For example, the equation for the formation of water is 2H2 + O2 = 2H2O. However, if you were asked to provide the equation for the fo...
by Faith Lee 2L
Fri Oct 09, 2020 12:03 am
Forum: Balancing Chemical Reactions
Topic: Naming compounds
Replies: 21
Views: 194

Re: Naming compounds

I believe Dr. Lavelle said the compounds would be provided for us, but if you're looking to learn more this is a really helpful website!

https://courses.lumenlearning.com/bound ... compounds/
by Faith Lee 2L
Wed Oct 07, 2020 2:59 pm
Forum: Limiting Reactant Calculations
Topic: Sapling Q10 Balanced Equation
Replies: 6
Views: 50

Re: Sapling Q10 Balanced Equation

I found the mass of the 2-butanone by using the density given, and then used the mole ratio of 1:1 to find the theoretical yield of the product. I didn't consider the magnesium nor the 1-bromopropane, but I don't believe you need it in order to solve the question correctly!

Hope this helps!
by Faith Lee 2L
Wed Oct 07, 2020 11:38 am
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 14
Views: 109

Re: Fractions

Praneetha and Mlouie are right! However, I believe the textbook states that you're allowed to have a fractional stoichiometric coefficient for a molecule if the question asks for a specific stoichiometric coefficient for a different molecule. For example, a balanced equation for the formation of wat...
by Faith Lee 2L
Wed Oct 07, 2020 11:17 am
Forum: Empirical & Molecular Formulas
Topic: Fundamentals Section F.19
Replies: 5
Views: 46

Re: Fundamentals Section F.19

Try using the mass percentages given as percentages of 100g rather than 194.19g/mol. It might take a little longer (since it will give you the empirical formula, which you have to convert to the molecular formula), but there is a smaller chance of making small errors :) I've attached my work below i...
by Faith Lee 2L
Tue Oct 06, 2020 2:33 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactants Help M11?
Replies: 3
Views: 23

Re: Limiting Reactants Help M11?

You would first need to use stoichiometry and the first equation to convert the mass of P4 to the mass of O2, and then compare them to see if there is excess O2. Since there is, we know that the second reaction occurs but does not have enough oxygen to use all the P4O6 from the first reaction, Ther...
by Faith Lee 2L
Sat Oct 03, 2020 2:29 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Fundamentals Problem E9
Replies: 3
Views: 122

Re: Fundamentals Problem E9

Fundamentals E Homework-1.jpg


Here's my work if you wanted to see the calculations written out! Hope this helps :)

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