Search found 100 matches

by Zainab Jamali 1H
Sat Feb 27, 2021 11:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridges
Replies: 20
Views: 40

Re: Salt Bridges

The salt bridge prevents ion build-up on either side of the galvanic cell and helps maintain a neutral charge as electrons flow between the two sides.
by Zainab Jamali 1H
Sat Feb 27, 2021 11:10 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Which Nesnst Equation
Replies: 6
Views: 25

Re: Which Nesnst Equation

The ln equation applies in all cases but the log equation can only be used for reactions at 25 degrees Celsius (or 298K).
by Zainab Jamali 1H
Sat Feb 27, 2021 11:06 pm
Forum: Balancing Redox Reactions
Topic: Determining which molecule is the oxidizing agent
Replies: 20
Views: 38

Re: Determining which molecule is the oxidizing agent

The oxidizing agent encourages oxidation of the other species by being reduced itself, so yes, you would be correct in saying that the oxidizing agent is the one that is reduced :)
by Zainab Jamali 1H
Sat Feb 27, 2021 11:05 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Sapling #17
Replies: 4
Views: 27

Re: Sapling #17

Yes, you would use the Nernst equation but you would use a combination of concentration values and partial pressures when solving for Q so it's a little different than what we're used to! Q = PH2/[H+]^2 Hope that helps!
by Zainab Jamali 1H
Sat Feb 27, 2021 11:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Oxidizing agent as anode?
Replies: 2
Views: 6

Re: Oxidizing agent as anode?

That would be correct! I was confused by the title of your question and thought you were asking if the oxidizing agent is at the anode haha but what you have here looks accurate :)
by Zainab Jamali 1H
Sun Feb 21, 2021 7:00 pm
Forum: Calculating Work of Expansion
Topic: Negative Work
Replies: 19
Views: 64

Re: Negative Work

If work is done on the system, w is a positive value. If the system does work, then w is a negative value. Hope that helps :)
by Zainab Jamali 1H
Sun Feb 21, 2021 6:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Open vs closed
Replies: 24
Views: 66

Re: Open vs closed

The difference is in what can be transferred in/out of a system:
Open systems: mass and energy
Closed systems: energy
Isolated systems: neither

It definitely is important to know what kind of system it is, especially for thermochemistry problems!
by Zainab Jamali 1H
Sun Feb 21, 2021 6:55 pm
Forum: Student Social/Study Group
Topic: Classes for next quarter?
Replies: 128
Views: 424

Re: Classes for next quarter?

I'm planning on taking Math 3C, LS7C, LS23L, a cluster, and a 1 unit seminar! I am a little concerned about the workload haha so I'm thinking about dropping one class depending on how overwhelming the first two weeks are :)
by Zainab Jamali 1H
Sun Feb 21, 2021 6:53 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Forward vs. Reverse
Replies: 15
Views: 30

Re: Forward vs. Reverse

The way the reaction is presented to you in the problem would generally be the forward reaction (unless stated otherwise). So if that reaction is reactants --> products, then its reverse is products --> reactants. Hope this helps :)
by Zainab Jamali 1H
Sun Feb 21, 2021 6:51 pm
Forum: Calculating Work of Expansion
Topic: Calculating W
Replies: 4
Views: 22

Re: Calculating W

You can use Boltzmann's entropy formula to solve for W in this question: S = (Boltzmann's constant)(lnW) --> W = e^(S/kB)
by Zainab Jamali 1H
Sun Feb 21, 2021 6:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: State function?
Replies: 36
Views: 106

Re: State function?

No, cell potential is not a state function but its symbol is a capital letter so I was confused too at first!
by Zainab Jamali 1H
Sun Feb 14, 2021 5:30 pm
Forum: Student Social/Study Group
Topic: Fav Shows of the Moment
Replies: 100
Views: 230

Re: Fav Shows of the Moment

schitt's creek!!! it's such a lovable show with a lovable cast and it's pretty light which is great during exam season :) my current favorite for sure!!
by Zainab Jamali 1H
Sun Feb 14, 2021 5:28 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity at Equilibrium?
Replies: 10
Views: 29

Re: Spontaneity at Equilibrium?

A reaction at equilibrium has a delta G equal to 0 so the reaction is not thermodynamically favorable in either direction and therefore nonspontaneous.
by Zainab Jamali 1H
Sun Feb 14, 2021 5:24 pm
Forum: Ideal Gases
Topic: R ideal gas constant
Replies: 25
Views: 64

Re: R ideal gas constant

This always trips me up when I'm trying to work quickly haha! The most definite way to know is to look at the units in your calculation and compare them to the units of the two different constants (they are very different!). Hope this helps :)
by Zainab Jamali 1H
Sun Feb 14, 2021 5:23 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm 2
Replies: 31
Views: 142

Re: Midterm 2

I believe he announced that midterm 2 will cover the part of outline 3 that was not on midterm 1 and all of outline 4!
by Zainab Jamali 1H
Sun Feb 14, 2021 5:19 pm
Forum: Student Social/Study Group
Topic: Balance / Self Care Tips
Replies: 41
Views: 122

Re: Balance / Self Care Tips

My biggest tip during exam season is to get a good amount of sleep the night before! Even if it means you don't get to study as much as you think you need to, your brain will function so much better during the test. In my experience, good sleep is much more effective the night before than last-minut...
by Zainab Jamali 1H
Sun Feb 14, 2021 5:17 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed vs Isolated System
Replies: 28
Views: 53

Re: Closed vs Isolated System

A closed system is not insulated so energy transfer can still occur but with an isolated system, energy cannot escape or enter the system.
by Zainab Jamali 1H
Sun Feb 07, 2021 4:36 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling #14
Replies: 6
Views: 66

Re: Sapling #14

Since it is an ideal gas, you can use PV=nRT and the given variables to solve for # of moles.
by Zainab Jamali 1H
Sun Feb 07, 2021 4:33 pm
Forum: Phase Changes & Related Calculations
Topic: H and q
Replies: 47
Views: 176

Re: H and q

q is the measurement of heat (transfer of heat energy) and H is the measurement of enthalpy! Enthalpy is a state function but heat is not. If the system in question is at constant pressure, then I believe delta H is equal to q.
by Zainab Jamali 1H
Sun Feb 07, 2021 4:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Can heat capacities be negative?
Replies: 52
Views: 157

Re: Can heat capacities be negative?

Heat capacities are always positive! Reaction enthalpies can definitely be positive or negative but the heat capacity term will always be positive.
by Zainab Jamali 1H
Sun Feb 07, 2021 4:28 pm
Forum: Phase Changes & Related Calculations
Topic: Vapor vs gas
Replies: 92
Views: 239

Re: Vapor vs gas

I believe vapor refers to when a substance that is commonly liquid/solid is in the gas phase. So in calculations, you would treat gases and vapors the same way!
by Zainab Jamali 1H
Sun Feb 07, 2021 4:24 pm
Forum: Student Social/Study Group
Topic: Studying When You Don't Want to
Replies: 48
Views: 141

Re: Studying When You Don't Want to

This happens to me a lot and what I try to do is to find a place to study that will give me a change of scenery. Either I go to the library, my backyard, my sister's room, or just somewhere where I don't feel so alone and isolated and that definitely helps me :)
by Zainab Jamali 1H
Sun Jan 31, 2021 6:48 pm
Forum: Administrative Questions and Class Announcements
Topic: 14C?
Replies: 23
Views: 122

Re: 14C?

I'm planning on waiting until fall 2021! I also thought it made sense to break between gen chem and o chem :)
by Zainab Jamali 1H
Sun Jan 31, 2021 6:45 pm
Forum: Student Social/Study Group
Topic: Go treat yourself after MT1!
Replies: 75
Views: 302

Re: Go treat yourself after MT1!

love this positive energy :)) thanks!
by Zainab Jamali 1H
Sun Jan 31, 2021 6:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Kc
Replies: 36
Views: 92

Re: K vs. Kc

K is the general variable for equilibrium constant. It can be written more specifically as Kc (concentration) or Kp (partial pressure). The one you use is dependent on the problem you're trying to solve and the given information. Hope that helps :)
by Zainab Jamali 1H
Sun Jan 31, 2021 6:40 pm
Forum: Student Social/Study Group
Topic: Spring 2021
Replies: 104
Views: 437

Re: Spring 2021

Hello! I'm currently taking Chem 14BL right now, and I just want to advise that this class, while not the most difficult material, is a lot of work. So if you think you are already going to have a busy schedule next quarter, you might want to consider whether you can handle this extra workload (wee...
by Zainab Jamali 1H
Sun Jan 31, 2021 6:32 pm
Forum: Student Social/Study Group
Topic: Work Life Balance
Replies: 44
Views: 152

Re: Work Life Balance

I totally agree!! one thing I've been doing recently to help counteract this a little bit is doing anything that doesn't involve a screen during my breaks between zoom calls. On days where I have a lot of classes back to back, I try to just take a break from screens, including my phone or TV, and go...
by Zainab Jamali 1H
Sun Jan 24, 2021 9:58 pm
Forum: Student Social/Study Group
Topic: Midterm Study Tips
Replies: 41
Views: 152

Re: Midterm Study Tips

textbook problems and review sessions!!
by Zainab Jamali 1H
Sun Jan 24, 2021 7:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Learning Q2 Percent Ionization
Replies: 2
Views: 26

Re: Sapling Learning Q2 Percent Ionization

When he taught %ionization in lecture, I believe Dr. Lavelle said it was the [conjugate]/[original substance] so the correct notation would be [A-]/[HA]. If the molar ratio of H+ and A- is 1:1, their equilibrium concentrations should be equal as they are both products of the reaction. Therefore, tec...
by Zainab Jamali 1H
Sun Jan 24, 2021 7:12 pm
Forum: Phase Changes & Related Calculations
Topic: Adding Heat but Temp remains constant
Replies: 11
Views: 81

Re: Adding Heat but Temp remains constant

So in that situation, the heat is being used to break the bonds/intramolecular forces so it doesn't affect the actual temperature of the substance.
by Zainab Jamali 1H
Sun Jan 24, 2021 7:10 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Sapling week 2 #9
Replies: 8
Views: 81

Re: Sapling week 2 #9

Hi! When the pH > pKa, the predominant species is charged because the environment around it is more basic (the pH is higher) than the species, so the acid will dissociate and become ionized to make the environment more acidic. When the pH < pKa, the predominant species is neutral because the enviro...
by Zainab Jamali 1H
Sun Jan 24, 2021 7:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Problem 5I.29
Replies: 4
Views: 37

Re: Problem 5I.29

Generally if the relevant K value is less than 10^-4, you can approximate when finding equilibrium concentrations! You can also double check by seeing if your value for x is less than 5% of the initial reactant concentration.
by Zainab Jamali 1H
Sun Jan 24, 2021 7:05 pm
Forum: Student Social/Study Group
Topic: Calculators
Replies: 34
Views: 119

Re: Calculators

You are allowed a scientific or graphing calculator, the equation/constant sheet, the periodic table, and scratch paper for the exam. Dr. Lavelle's website has the specific periodic table and equation sheet that is permitted for the test.
by Zainab Jamali 1H
Sun Jan 17, 2021 5:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: sapling week #1 Question 6
Replies: 4
Views: 23

Re: sapling week #1 Question 6

[H2] should be cubed rather than squared! Hope this helps :)
by Zainab Jamali 1H
Sun Jan 17, 2021 5:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pure Liquids (Solutes)
Replies: 7
Views: 18

Re: Pure Liquids (Solutes)

This might be an oversimplification but my understanding is that anything labeled in the equation with (s) or (l) should not be included in the K expression. I think only substances that are either gaseous or aqueous should be included.
by Zainab Jamali 1H
Sun Jan 17, 2021 5:50 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle and Pressure
Replies: 6
Views: 40

Re: Le Chatelier's Principle and Pressure

Pressure and volume are inversely related. When pressure increases, volume decreases --> when there is less space to occupy (volume), the reaction will favor the side with fewer moles.
by Zainab Jamali 1H
Sun Jan 17, 2021 5:44 pm
Forum: Student Social/Study Group
Topic: Comfort Movies
Replies: 128
Views: 347

Re: Comfort Movies

definitely disney classics!! and also harry potter (especially the early ones which are much less dark than the later ones)
by Zainab Jamali 1H
Sun Jan 17, 2021 5:38 pm
Forum: Ideal Gases
Topic: Inverse Kc [ENDORSED]
Replies: 41
Views: 121

Re: Inverse Kc [ENDORSED]

inverse of Kc is to the reverse reaction what Kc is to the forward reaction. that's how I remember it!
by Zainab Jamali 1H
Sun Jan 17, 2021 5:35 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q > K, Q< K
Replies: 25
Views: 100

Re: Q > K, Q< K

IMG_2B91BABCC7E2-1.jpeg

This visual helps me remember in a really simple way! If Q>K then more reactants will form and if Q<K then more products will form in order to reach equilibrium where Q=K.
by Zainab Jamali 1H
Sun Jan 10, 2021 7:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Grading for Chemistry Community Posts
Replies: 12
Views: 60

Re: Grading for Chemistry Community Posts

Emily Tieu 2K wrote:^ This is also my first time taking Professor Lavelle. To clarify, is it 50 times by week 10 or 5 times every week?


Technically, it is 5 posts per week but I think the grading depends on the TAs. To be on the safe side, try to do 5 posts every week :)
by Zainab Jamali 1H
Sun Jan 10, 2021 7:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling homework due date
Replies: 14
Views: 87

Re: Sapling homework due date

josephspindler2H wrote:Thanks for clarifying that the homework is due next Sunday 1/17! Out of curiosity, does anyone know if week 2 homework also be due that day?


No, the next homework assignment will include content from weeks 2-4 so it will be due the Sunday of Week 4 I believe.
by Zainab Jamali 1H
Sun Jan 10, 2021 7:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration
Replies: 12
Views: 81

Re: Concentration

The values of volume and moles can never be negative so the ratio of the two (concentration) can also never be negative.
by Zainab Jamali 1H
Sun Jan 10, 2021 7:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Q
Replies: 53
Views: 209

Re: K vs. Q

You're correct! I believe Q can be calculated at any time during the reaction (including at equilibrium) but if it is specified that the reaction is at equilibrium you can use K instead.
by Zainab Jamali 1H
Sun Jan 10, 2021 7:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: increasing total pressure in equilibria
Replies: 11
Views: 67

Re: increasing total pressure in equilibria

When pressure is increased, the equilibrium will favor the side that has less moles of gas. When volume is increased, the equilibrium will favor the side with more moles of gas.
by Zainab Jamali 1H
Tue Dec 15, 2020 6:17 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8772
Views: 1490906

Re: Post All Chemistry Jokes Here

What does formaldehyde look like on vacation?
flat,1000x1000,075,f.u1.jpg
Casual-dehyde!
by Zainab Jamali 1H
Tue Dec 15, 2020 6:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 337
Views: 140073

Re: Saying Thank You to Dr. Lavelle

Thank you so much for this quarter Dr. Lavelle!! Your lectures were engaging and I really wish I could have taken your class in person! Nonetheless, I am really looking forward to next quarter in 14B! I hope you stay safe and enjoy the holidays :)
by Zainab Jamali 1H
Tue Dec 15, 2020 6:04 pm
Forum: Student Social/Study Group
Topic: Staying Motivated
Replies: 20
Views: 162

Re: Staying Motivated

Hey I know how you feel, this quarter my home life was more chaotic than usual and mental and physical health issues certainly did not help my motivation. What I found to help was that for classes like this where you dread wanting to go and feel you can fall behind easily, DO IT FIRST! Its harder s...
by Zainab Jamali 1H
Tue Dec 15, 2020 6:02 pm
Forum: Student Social/Study Group
Topic: How are you?
Replies: 117
Views: 876

Re: How are you?

Just finished my second final! Slowly running out of mental energy but looking forward to break :))
by Zainab Jamali 1H
Tue Dec 15, 2020 6:01 pm
Forum: Student Social/Study Group
Topic: Grades
Replies: 29
Views: 234

Re: Grades

we have until 10 am thursday morning to post on chem community!
by Zainab Jamali 1H
Sun Dec 06, 2020 3:52 pm
Forum: Administrative Questions and Class Announcements
Topic: Lectures not loading
Replies: 6
Views: 76

Re: Lectures not loading

Zainab Jamali 3I wrote:The same thing happened to me! Once I reconnected to the campus VPN, the video loaded and started playing so maybe try that?


Actually scratch that. I am still connected to the VPN and it just stopped working again :(
by Zainab Jamali 1H
Sun Dec 06, 2020 3:51 pm
Forum: Administrative Questions and Class Announcements
Topic: Will fundamentals problems be on our final?
Replies: 6
Views: 40

Re: Will fundamentals problems be on our final?

I would think so because the final is cumulative for the whole quarter, but someone please correct me if I'm wrong :)
by Zainab Jamali 1H
Sun Dec 06, 2020 3:49 pm
Forum: Student Social/Study Group
Topic: Studying for Final Exam
Replies: 57
Views: 397

Re: Studying for Final Exam

I am definitely going to take advantage of all the review sessions these week as well as Professor Lavelle's review session. I think it is super helpful to do practice problems with other students and be able to ask the UA's questions while doing so! Agreed! Also, hearing the answers to other stude...
by Zainab Jamali 1H
Sun Dec 06, 2020 3:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Partial Credit on the Final
Replies: 6
Views: 77

Re: Partial Credit on the Final

I was wondering the same thing because midterm 1 did have partial credit opportunities but midterm 2 did not. Since the final will be cumulative, I hope at least some questions will have partial credit opportunities.
by Zainab Jamali 1H
Sun Dec 06, 2020 3:17 pm
Forum: Naming
Topic: HW Question #1
Replies: 7
Views: 107

Re: HW Question #1

Why is it dichloro? I thought there were 3 chlorine atoms. There are only two chlorine ligands within the complex ion (within the brackets). When you name the first part of a coordination compound, you are naming only the complex ion so it would be "dichloro" and the third chlorine in the...
by Zainab Jamali 1H
Sun Dec 06, 2020 3:10 pm
Forum: Naming
Topic: Order of Ligands/naming
Replies: 28
Views: 146

Re: Order of Ligands/naming

Ligands are listed in alphabetical order by the first letter of the ligand (not the numerical prefix). Hope this helps!
by Zainab Jamali 1H
Sun Dec 06, 2020 3:10 pm
Forum: Administrative Questions and Class Announcements
Topic: Lectures not loading
Replies: 6
Views: 76

Re: Lectures not loading

The same thing happened to me! Once I reconnected to the campus VPN, the video loaded and started playing so maybe try that?
by Zainab Jamali 1H
Sun Nov 29, 2020 4:49 pm
Forum: Resonance Structures
Topic: Sapling Week 8 Q17
Replies: 6
Views: 54

Re: Sapling Week 8 Q17

reva_bajjuri wrote:does anyone know why exactly the ring structure is stable/what the benefit of forming a ring is?


I'm wondering the same thing!
by Zainab Jamali 1H
Sun Nov 29, 2020 4:47 pm
Forum: Student Social/Study Group
Topic: Tips for Staying Focused
Replies: 52
Views: 598

Re: Tips for Staying Focused

I have been struggling with the same thing so this thread is really helpful! Thank you :)
by Zainab Jamali 1H
Sun Nov 29, 2020 4:46 pm
Forum: Coordinate Covalent Bonds
Topic: Hydrogen bonds
Replies: 19
Views: 169

Re: Hydrogen bonds

The hydrogen bond relies partially on a partial positive charge on the hydrogen. When the H is attached to a carbon, there is very little polarity and the partial charge on hydrogen isn't there to bond to the partial negative on the bonding atom.
by Zainab Jamali 1H
Sun Nov 29, 2020 4:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Angle Masterlist
Replies: 5
Views: 55

Re: Angle Masterlist

This is really helpful, thank you!!
by Zainab Jamali 1H
Sun Nov 29, 2020 4:36 pm
Forum: Student Social/Study Group
Topic: Final Study
Replies: 32
Views: 220

Re: Final Study

I have been reviewing problems in the book and on Sapling. Are there any specific Youtube channels anyone can recommend that effectively review this course's material? Personally, I watch organic chemistry tutor on youtube when I need clarification on concepts! The videos are very detailed, clear, ...
by Zainab Jamali 1H
Sat Nov 21, 2020 1:48 pm
Forum: Student Social/Study Group
Topic: Study Tips for Final Exam
Replies: 57
Views: 450

Re: Study Tips for Final Exam

I find that reading the textbook in conjunction with Dr. Lavelle's lectures is very helpful. If there are concepts I still can't quite grasp I definitely rely on Organic Chemistry Tutor on youtube haha. Once you have reviewed content, try testing yourself with practice textbook questions.
by Zainab Jamali 1H
Sat Nov 21, 2020 1:46 pm
Forum: Octet Exceptions
Topic: Octet Rule Exceptions
Replies: 20
Views: 217

Re: Octet Rule Exceptions

Thanks for asking this question! This thread is very helpful :)
by Zainab Jamali 1H
Sat Nov 21, 2020 1:43 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8772
Views: 1490906

Re: Post All Chemistry Jokes Here

The name's Bond. Ionic Bond. Taken, not shared.
by Zainab Jamali 1H
Sat Nov 21, 2020 1:39 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8772
Views: 1490906

Re: Post All Chemistry Jokes Here

A photon checks into a hotel and is asked if he needs any help with his luggage. He says, "No, I'm traveling light." :)
by Zainab Jamali 1H
Sat Nov 21, 2020 1:32 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B and 14BL
Replies: 13
Views: 165

Re: 14B and 14BL

I think I will be taking 14B in winter and BL in spring, as I personally want to have a stronger foundation first before delving into lab stuff, but I've heard that either way you do it is fine! I'm planning on doing the same thing! I feel like knowing the textbook content well before taking the la...
by Zainab Jamali 1H
Sun Nov 15, 2020 12:24 pm
Forum: Lewis Structures
Topic: breaking the octet rule
Replies: 4
Views: 45

breaking the octet rule

Does anyone have a good way to remember which atoms can break the ocet rule during bonding, like which atoms can have an expanded octet and which atoms can have an incomplete octet (besides the first 4 elements)?
by Zainab Jamali 1H
Sun Nov 15, 2020 12:20 pm
Forum: Lewis Structures
Topic: Sapling Question -- Formula of Ions
Replies: 1
Views: 30

Re: Sapling Question -- Formula of Ions

I was wondering the same thing. The question did not give the formulas for these polyatomic ions. Are we meant to know basic polyatomic ion names and charges for the midterm or will Dr. Lavelle provide the formulas on the exam?
by Zainab Jamali 1H
Sun Nov 15, 2020 12:19 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Clarification
Replies: 8
Views: 37

Re: Clarification

Right! I find the overall charge helps me check to make sure I have assigned the individual formal charges correctly.
by Zainab Jamali 1H
Sun Nov 15, 2020 12:16 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 19
Views: 102

Re: Resonance

Resonance structures have delocalized electrons which are very stable and contribute to the overall stability of the molecule.
by Zainab Jamali 1H
Mon Nov 09, 2020 10:49 am
Forum: Resonance Structures
Topic: Formal charges in regards to resonance strucures
Replies: 3
Views: 29

Re: Formal charges in regards to resonance strucures

I believe formal charge is allocated per atom, but the collective formal charges of all atoms in a molecule add up to the total formal charge of the molecule. Right, that makes sense! I still would like to know if there is a way to determine which atom will hold that formal charge in resonance stru...
by Zainab Jamali 1H
Sun Nov 08, 2020 10:42 pm
Forum: Resonance Structures
Topic: Formal charges in regards to resonance strucures
Replies: 3
Views: 29

Formal charges in regards to resonance strucures

During last Monday's lecture, Dr. Lavelle discussed how multiple bond character was spread over the molecule in the case of resonance structures. Since adding a double bond would change the formal charge of one atom in the molecule, how is that formal charge allocated? Is it also spread over the mol...
by Zainab Jamali 1H
Sun Nov 08, 2020 7:39 pm
Forum: Lewis Structures
Topic: Lewis Acids/Bases
Replies: 4
Views: 17

Lewis Acids/Bases

Hi! I was wondering if someone could clarify what distinguishes a Lewis acid from a Lewis base? Is it based on whether they lose or gain electrons during bonding?
by Zainab Jamali 1H
Sun Nov 08, 2020 7:36 pm
Forum: Student Social/Study Group
Topic: Lecture on Veteran's Day
Replies: 10
Views: 64

Re: Lecture on Veteran's Day

Professor Lavelle also mentioned at one point that he would not be holding office hours on Wednesday due to the national holiday so I assume that means he will not have a lecture either.
by Zainab Jamali 1H
Sun Nov 08, 2020 7:31 pm
Forum: Bond Lengths & Energies
Topic: Delocalized Electrons
Replies: 5
Views: 45

Re: Delocalized Electrons

In addition, when electrons are delocalized due to resonance, it results in a more stable molecule.
by Zainab Jamali 1H
Sun Nov 08, 2020 7:03 pm
Forum: Resonance Structures
Topic: Electron spin
Replies: 12
Views: 52

Re: Electron spin

There really isn't a way to determine if the electron is spinning +1/2 or -1/2. Pretty much the only practical reason why those two numbers exist is to communicate that the two electrons in the state are spinning in opposite directions, in that they are not parallel. I agree, it is simply to differ...
by Zainab Jamali 1H
Sun Nov 08, 2020 6:58 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8772
Views: 1490906

Re: Post All Chemistry Jokes Here

I would post another chemistry joke, but all the good ones Argon :)
by Zainab Jamali 1H
Sun Nov 01, 2020 9:17 pm
Forum: Student Social/Study Group
Topic: Textbook vs Lectures vs Other Methods
Replies: 17
Views: 134

Re: Textbook vs Lectures vs Other Methods

Hi! I am currently in 14a. Personally, I have found that the lectures and sapling assignments cover the material really well. I use the textbook to review concepts and the textbook problems to prepare for the midterm exam (especially for concepts I have more difficulty with).
by Zainab Jamali 1H
Sun Nov 01, 2020 9:15 pm
Forum: DeBroglie Equation
Topic: When to Use De Broglie
Replies: 16
Views: 130

Re: When to Use De Broglie

The simplest way to think about it is that E = hv and c = v(lambda) applies to electromagnetic radiation and deBroglie's equation applies to particles with mass, including all the subatomic particles.
by Zainab Jamali 1H
Sun Nov 01, 2020 9:12 pm
Forum: Quantum Numbers and The H-Atom
Topic: Sapling Question (excited-state, ground-state)
Replies: 4
Views: 55

Re: Sapling Question (excited-state, ground-state)

For this question, you can start by finding the total number of electrons. That number is equivalent to the atomic number of the atom so, using the periodic table, you can determine what element it is.
by Zainab Jamali 1H
Fri Oct 30, 2020 5:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Exam Scores
Replies: 15
Views: 115

Midterm Exam Scores

Hi! Does anyone know where and how to access midterm exam scores when they're posted?
by Zainab Jamali 1H
Fri Oct 30, 2020 5:52 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Textbook Question 1B.27
Replies: 3
Views: 30

Re: Textbook Question 1B.27

Hi! It is a typo in the answer key. So you're correct, \Delta v = 10 m/s. You can find the correct solution in Solution Manual Errors (https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/Solution_Manual_Errors_7Ed.pdf), which is also posted on Dr. Lavelle's website. Hope this helps :)...
by Zainab Jamali 1H
Fri Oct 30, 2020 11:22 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Textbook Question 1B.27
Replies: 3
Views: 30

Textbook Question 1B.27

Hi everyone! I am a little confused on the procedure for this question: "A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at 5.00 +/- 5.0 m/s. What is the minimum uncertainty in its position?" I set up the equation using delta v = 10 because of the +/- but the answer key ...
by Zainab Jamali 1H
Sun Oct 25, 2020 2:26 pm
Forum: Student Social/Study Group
Topic: Textbook sections on the midterm?
Replies: 3
Views: 36

Textbook sections on the midterm?

Hi! Could someone clarify exactly which sections of the textbook will be on the midterm? I have heard a couple different answers and I just want to make sure I don't miss anything :)
by Zainab Jamali 1H
Sun Oct 25, 2020 2:22 pm
Forum: Student Social/Study Group
Topic: Study Groups/Zoom Sessions?
Replies: 3
Views: 49

Study Groups/Zoom Sessions?

Hi all! Does anyone know of any study/review sessions, official or unofficial, coming up this week? I could use the extra structured practice/study time before my exam on Friday! Thanks :)
by Zainab Jamali 1H
Sun Oct 25, 2020 2:19 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1383

Re: How are you studying?

I have found that taking notes by hand and doing practice problems are the two best ways to really lock down certain concepts! However, for some of the tougher topics I turn to youtube for some helpful tips and tricks and it can be very useful if you're having trouble conceptualizing or visualizing ...
by Zainab Jamali 1H
Sun Oct 25, 2020 2:18 pm
Forum: Student Social/Study Group
Topic: Midterm Question
Replies: 9
Views: 71

Re: Midterm Question

As a follow up question, will we have access to the electromagnetic spectrum or are we expected to memorize the wavelength ranges for the different wave type?
by Zainab Jamali 1H
Sat Oct 24, 2020 12:55 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Sapling question 8
Replies: 2
Views: 43

Sapling question 8

The question is: A blue line is observed at 486.1 nm in the spectrum of atomic hydrogen. Determine the values of n for the beginning and ending energy levels of the electron during the emission of energy that leads to this spectral line. What I'm wondering is how do you determine based on wavelength...
by Zainab Jamali 1H
Thu Oct 22, 2020 5:18 pm
Forum: Student Social/Study Group
Topic: Official midterm review sessions
Replies: 3
Views: 46

Re: Official midterm review sessions

I heard that Justin (a UA) is hosting a midterm review during his workshop on Saturday from 12-1!
by Zainab Jamali 1H
Sat Oct 17, 2020 10:20 pm
Forum: Properties of Light
Topic: Study Advice
Replies: 50
Views: 305

Re: Study Advice

How do I go about accessing the step-up sessions? And is there a pre-decided set of problems that they go over in each session and if so, would I need to complete them before attending?
by Zainab Jamali 1H
Sat Oct 17, 2020 10:19 pm
Forum: SI Units, Unit Conversions
Topic: Given Unit Conversions?
Replies: 6
Views: 43

Given Unit Conversions?

As far as unit conversions, I am curious as to what values are going to be given on the exams, if any? For example imperial to metric conversions are not always easy to remember, will common ones be available to us as a resource during exams?
by Zainab Jamali 1H
Sat Oct 17, 2020 10:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Accessing the E-textbook [ENDORSED]
Replies: 107
Views: 7308

Re: Accessing the E-textbook [ENDORSED]

For anyone who ordered their textbook from the UCLA store and already received it, was it a physical copy? and if so, did it include an access code for sapling and/or the e-book? It’s an e book for this course because there’s videos and links inside the book. You should get your code on a piece of ...
by Zainab Jamali 1H
Sat Oct 17, 2020 10:13 pm
Forum: Properties of Electrons
Topic: Wave properties of elecrons
Replies: 5
Views: 75

Re: Wave properties of elecrons

I had the same question! Thank you for starting this thread, I vaguely understood the concept but its much clearer now.
by Zainab Jamali 1H
Sat Oct 17, 2020 10:09 pm
Forum: Properties of Electrons
Topic: Electrons ejected
Replies: 7
Views: 58

Re: Electrons ejected

This is a great question! It would emit more photons of the same energy, therefore ejecting more electrons (as long as the energy of the photons is greater than or equal to the threshold energy of the electrons).
by Zainab Jamali 1H
Sat Oct 17, 2020 10:07 pm
Forum: Photoelectric Effect
Topic: Frequency vs. Intensity
Replies: 16
Views: 131

Re: Frequency vs. Intensity

In short, intensity is how many photons are hitting the metal surface while frequency influences the actual energy of the light. This is why frequency is key to the photoelectric effect: the energy of the light (affected by the frequency (E = h*v)) has to be greater than or equal to the threshold en...
by Zainab Jamali 1H
Thu Oct 08, 2020 11:06 am
Forum: Student Social/Study Group
Topic: Office Hours
Replies: 7
Views: 57

Re: Office Hours

It honestly really helps me review to hear what questions other people have because a lot of times I don't even know what I don't know. I think I'll start dropping into office hours now :)
by Zainab Jamali 1H
Thu Oct 08, 2020 11:04 am
Forum: SI Units, Unit Conversions
Topic: SI Base Unit Kg
Replies: 5
Views: 52

Re: SI Base Unit Kg

As a general rule of them look at the unit in the equations you are using. While kilograms is the SI unit, there are many lab instances where using grams is preferred. Just make sure to always check the equation and what it requires (g or kg) and to see what units the final answer asks for and do y...
by Zainab Jamali 1H
Thu Oct 08, 2020 10:57 am
Forum: SI Units, Unit Conversions
Topic: Significant Figures Using the Periodic Table
Replies: 13
Views: 145

Re: Significant Figures Using the Periodic Table

Jaden Ji 3K wrote:Here's the link to the textbook's periodic table!
https://www.saplinglearning.com/ibiscms ... d=13094939
I've been using this one and I've gotten answers right using all the decimal places and correct sig figs with this.


This is a great resource, thank you!
by Zainab Jamali 1H
Thu Oct 08, 2020 10:56 am
Forum: SI Units, Unit Conversions
Topic: Significant Figures Using the Periodic Table
Replies: 13
Views: 145

Re: Significant Figures Using the Periodic Table

I was wondering the same thing, thank you for starting this thread! Personally, I have always just rounded to three digits but the information in this thread is helpful!
by Zainab Jamali 1H
Thu Oct 08, 2020 10:52 am
Forum: Administrative Questions and Class Announcements
Topic: Accessing the E-textbook [ENDORSED]
Replies: 107
Views: 7308

Re: Accessing the E-textbook [ENDORSED]

For anyone who ordered their textbook from the UCLA store and already received it, was it a physical copy? and if so, did it include an access code for sapling and/or the e-book?

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