Search found 51 matches

by Imelda Mena 3I
Sat Dec 08, 2018 6:27 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 7746

Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

Kathryn 3D wrote:Can someone explain 41d - how many atoms in thymine could form a hydrogen bond. The answer is 4 but I only see 2--on either oxygen. Where are the other 2?


The other two come from the two Nitrogens in the structure.
by Imelda Mena 3I
Sat Dec 08, 2018 6:26 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 7746

Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

For #31, would it also be correct to put NO2 in the complex or does it have to be ONO? I would say it has to be ONO, nitrito, because if you write NO2 that can be mistaken with nitro. Which seem similar but are not because the central atom for each differentiates. I think we should specify ONO-, bu...
by Imelda Mena 3I
Sat Dec 08, 2018 4:26 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 7746

Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

Can someone explain 33b? For this question it's crucial to realize that NaOH is a strong base and therefore we know that it completely dissociates. Once we have identified this, we know that 0.55M NaOH will produce 0.55 OH- because it completely dissociates. From here all that is left is plug in th...
by Imelda Mena 3I
Sat Dec 08, 2018 4:21 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 7746

Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

Sydney Takeda 1G wrote:For #31, would it also be correct to put NO2 in the complex or does it have to be ONO?


I would say it has to be ONO, nitrito, because if you write NO2 that can be mistaken with nitro. Which seem similar but are not because the central atom for each differentiates.
by Imelda Mena 3I
Sat Dec 08, 2018 4:18 pm
Forum: Administrative Questions and Class Announcements
Topic: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]
Replies: 118
Views: 7746

Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

Can someone explain the bond angles in number 18? For number 18, you have to look at the structure with all bonds, atoms, and lone pairs to make it easy to see what is going on. Once you have a structure that includes every thing see what shapes you have for each atom and from the shape determine w...
by Imelda Mena 3I
Thu Dec 06, 2018 11:00 am
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Replies: 135
Views: 28868

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]

Leela_Mohan3L wrote:How do you go about doing #3 in the acid/base section?


Yes, can someone explain how to solve #3 on the second page of worksheet 9 please?
by Imelda Mena 3I
Thu Dec 06, 2018 10:59 am
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Replies: 135
Views: 28868

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]

Kenan Kherallah 1A wrote:Im just wondering why the tail has a -1 charge since for me when I calculated the formal charges of the nitrogens connected to Co I got +1, +1, +1, +1, and 0
Wouldnt that give an overall +4 charge for the tail?


I also have the same confusion can some explain please?
by Imelda Mena 3I
Wed Dec 05, 2018 11:49 am
Forum: Naming
Topic: 7th edition 9C.3: Potassium Hexacyanidochromate (III)
Replies: 2
Views: 35

Re: 7th edition 9C.3: Potassium Hexacyanidochromate (III)

I understand how to get the formula from this coordination compound name when looking at the answer however I am still confused on a few things. 1) for things that have atoms/molecules outside of brackets, will the charges from the inside and outside always cancel each other out? In other words, wil...
by Imelda Mena 3I
Wed Dec 05, 2018 9:08 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 4
Views: 122

Re: Ligands

The easiest way to determine how many ligands are bounded to any central atom is by looking at the Lewis structure, I always do this first. Even if the problem does not ask for it. Another helpful thing is that when a chemical formula has a subscript that usually means that it will be directly bound...
by Imelda Mena 3I
Wed Dec 05, 2018 1:30 am
Forum: Conjugate Acids & Bases
Topic: Conjugates
Replies: 2
Views: 58

Re: Conjugates

Andrea pretty much explained it already but to give you an example, we can look at the common reaction of: HCl + H2O --> Cl- + H3O+ and from this we know that HCl is an acid and it produces the Cl- which is its conjugate base, likewise, H2O which is a base turns into H3O+ which is its conjugate acid...
by Imelda Mena 3I
Tue Dec 04, 2018 9:58 am
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Replies: 135
Views: 28868

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]

Disregard my previous post, for some reason it hadn't downloaded all the comments in the thread. I just saw worksheet 9!
by Imelda Mena 3I
Thu Nov 29, 2018 11:42 am
Forum: Sigma & Pi Bonds
Topic: Why are sigma bonds stronger than pi bonds?
Replies: 10
Views: 451

Re: Why are sigma bonds stronger than pi bonds?

I understand the argument that sigma bonds are stronger because they have more overlap, but aren't longer bonds weaker because they are more easily broken? aka sigma bonds versus double bonds which are shorter in length as as a result we say they are stronger because they don't break as easily?
by Imelda Mena 3I
Wed Nov 28, 2018 8:46 pm
Forum: Dipole Moments
Topic: Polarizability vs Polarizing power
Replies: 8
Views: 158

Re: Polarizability vs Polarizing power

Thank you for the clarification Kassidy! And when determining which has a higher polarizability the size matters more right?
by Imelda Mena 3I
Wed Nov 28, 2018 11:55 am
Forum: Dipole Moments
Topic: Polarizability vs Polarizing power
Replies: 8
Views: 158

Re: Polarizability vs Polarizing power

In determining which molecules have higher polarizing power, what is more significant their charge or their size? For example what is the process we take to determine Rb+ has a higher polarizing power than Sr2+?
by Imelda Mena 3I
Mon Nov 26, 2018 9:09 pm
Forum: Lewis Structures
Topic: HW #3.67b (6th Ed)
Replies: 2
Views: 51

HW #3.67b (6th Ed)

Hi! Although this problem is not asking for the Lewis structure I was wondering what the most stable Lewis structure for ClO2 would be? I got Cl as the central atom with the two O at each side. With two double bonds and 3 e- on the Cl. Is this the most stable structure? The solutions show single bon...
by Imelda Mena 3I
Mon Nov 26, 2018 8:36 pm
Forum: Lewis Structures
Topic: hydrogen sulfite ion, HSO3-
Replies: 2
Views: 49

Re: hydrogen sulfite ion, HSO3-

Oh okay thank you! So the structure that I described above is still one possible structure but it is less stable?
by Imelda Mena 3I
Mon Nov 26, 2018 6:11 pm
Forum: Lewis Structures
Topic: hydrogen sulfite ion, HSO3-
Replies: 2
Views: 49

hydrogen sulfite ion, HSO3-

Hi! Homework problem 3.57b from the 6th edition asks for the Lewis structure of hydrogen sulfite ion and I got a different answer than the one on the answer key. Can someone explain how they got the H attached to O and not S (the central atom)? I got a tetrahedral shape, with S as the central atom a...
by Imelda Mena 3I
Sun Nov 25, 2018 5:01 pm
Forum: Sigma & Pi Bonds
Topic: Location of Sigma and Pi Bonds
Replies: 5
Views: 87

Re: Location of Sigma and Pi Bonds

Additionally, a sigma bond is a single bond meaning that two atoms share 2 electrons. While a pi bond is a double bond, however it's important you remember that 1 pi bond also has 1 sigma bond. Now if you look at a triple bond, that has 1 sigma bond and 2 pi bonds. Hope that helps!
by Imelda Mena 3I
Sun Nov 25, 2018 4:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 3
Replies: 6
Views: 190

Re: Test 3

Other than the VSEPR model, what other concepts will be on Test 3? I thought there was an outline that listed all topics for each quiz but now I can't find it.
by Imelda Mena 3I
Wed Nov 14, 2018 11:32 am
Forum: Octet Exceptions
Topic: Radicals
Replies: 16
Views: 541

Re: Radicals

Does anyone know if there are certain atoms that typically get the unpaired electron in a radical molecule?
by Imelda Mena 3I
Wed Nov 14, 2018 11:23 am
Forum: Octet Exceptions
Topic: Radicals
Replies: 16
Views: 541

Re: Radicals

Just for clarification when we say radical we can mean both the molecule with the unpaired valence electron OR the single electron as well? The word is used to describe both?
by Imelda Mena 3I
Wed Nov 14, 2018 10:49 am
Forum: Lewis Structures
Topic: HW #3.49 (6th Ed)
Replies: 1
Views: 70

HW #3.49 (6th Ed)

Hi all!

For this HW problem, why do we have the oxygen in parts a and c have a positive charge of 1 if it is more electronegative than N and C?
by Imelda Mena 3I
Wed Nov 07, 2018 11:48 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 7
Views: 209

Re: Formal Charge

Well in a lot of cases not all of the atoms can have a formal charge of zero. In Lewis structures, I think we want as many atoms to have a formal charge of 0 as possible, but its especially important that the central atom have a formal charge of 0. Additionally there are only a few atoms that can h...
by Imelda Mena 3I
Wed Nov 07, 2018 11:44 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 7
Views: 209

Re: Formal Charge

Are negative formal charges more preferable in terms of stability over positive formal charges?
by Imelda Mena 3I
Wed Nov 07, 2018 11:38 am
Forum: Ionic & Covalent Bonds
Topic: Chemical formula from compound name
Replies: 2
Views: 73

Chemical formula from compound name

Hey so some of the problems from the homework for the Chemical Bonds section asks us to give the chemical formula when we are given the name of a compound. The problems I am referring to are from chapter 3 #25 and 27 (from the 6th edition). I was able to figure out the chemical formula for most of t...
by Imelda Mena 3I
Sun Nov 04, 2018 11:55 pm
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 5526

Re: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]

Question 6b is asking if a Helium atom or a "new" element GarBreadium have longer wavelengths. The answer key says the GarBreadium will have a longer wavelength but isn't it He because it is less heavy, therefore the denominator in de Broglie's equation \lambda =h/m\cdot v be smaller, corr...
by Imelda Mena 3I
Sat Nov 03, 2018 12:30 pm
Forum: Quantum Numbers and The H-Atom
Topic: degeneracy of the a 4p orbital
Replies: 9
Views: 522

Re: degeneracy of the a 4p orbital

So we are not taking into account the spin of the electrons? I thought that the energy of an electron did not change if the electron had spin up or down. So for a 4p orbital, would we not have: n=4, l=1, m_l=1,0,-1 and m_s = +1/2,-1/2; a total degeneracy of 6?
by Imelda Mena 3I
Sat Nov 03, 2018 11:26 am
Forum: Administrative Questions and Class Announcements
Topic: Discussion Test Answer Key
Replies: 1
Views: 97

Discussion Test Answer Key

Hi,

Is there any way we can get an answer key for the test we do in discussion section so we can work out the problems we got wrong for preparation for midterms and future tests?

Thank you in advance!
by Imelda Mena 3I
Wed Oct 31, 2018 9:49 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3.5 c&d
Replies: 2
Views: 79

Re: 3.5 c&d

Okay this makes a bit more sense now! So these are the electron configuration for the ions now what if we were ask for the electron configuration of Nickel (Ni)? Would it be [Ar]3d^8 4s ^2?
by Imelda Mena 3I
Wed Oct 31, 2018 8:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Configurations involving f-orbital
Replies: 1
Views: 39

Re: Configurations involving f-orbital

The f-block is added right after element number 57, Lanthanum (La).
by Imelda Mena 3I
Wed Oct 31, 2018 8:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3.5 c&d
Replies: 2
Views: 79

3.5 c&d

Can someone explain the answers to these two question please. (c) is asking for ground state electron configuration for Ga3+ and (d) is asking for Tl3+. Why the electron configuration for the ion Tl3+ is [Xe]4f^14 5d^10? I thought it was [Xe]4f^14 5d^8 6s^2? Same thing with Ga3+, I thought it was [A...
by Imelda Mena 3I
Wed Oct 31, 2018 8:26 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cu2+ configuration
Replies: 2
Views: 63

Re: Cu2+ configuration

Yea! It is easier to remove the electrons that are on the outer shell. I think it helps if you start with the electron configuration of Cu first which from lecture we know it is one of the special exceptions as (Cu): [Ar] 3d^104s^1. From there you can see that the electron configuration for the ion ...
by Imelda Mena 3I
Wed Oct 31, 2018 8:17 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3.5a on 6th Edition
Replies: 1
Views: 52

Re: 3.5a on 6th Edition

Hi! So this is the one electron configuration that I got right out of all 4 parts. As you might recall from lecture, copper (Cu) is one of the exceptions that Dr. Lavelle talked about. So the electron configuration of just Cu is [Ar]3d^104s^1. However the question is asking for the electron configur...
by Imelda Mena 3I
Wed Oct 24, 2018 11:48 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Value of Delta X
Replies: 8
Views: 252

Re: Value of Delta X

So if the radius is given that is the electron's uncertainty in position? Or do we have to multiple it by 2 so it can be the diameter?
by Imelda Mena 3I
Wed Oct 24, 2018 8:49 pm
Forum: DeBroglie Equation
Topic: Remembering mass of electrons for tests
Replies: 6
Views: 155

Re: Remembering mass of electrons for tests

Like everyone already said, the mass of an electron will be given to us. Here is the link to the formula and constant sheet that will be provided to us for tests, midterms, and exams. https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf
by Imelda Mena 3I
Wed Oct 24, 2018 8:45 pm
Forum: Properties of Light
Topic: Visible Light Spectrum... ?
Replies: 6
Views: 128

Re: Visible Light Spectrum... ?

I was wondering the same thing since in a couple of the HW problems it ask in what spectrum a certain wavelength falls into. Thanks for the clarification! I will make sure to know the wavelength for visible, ultraviolet, and infrared. But do we also need to know the frequencies of these?
by Imelda Mena 3I
Wed Oct 24, 2018 7:58 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Replies: 135
Views: 28868

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]

Hi! Where do these workshops take place? I would like to attend.
by Imelda Mena 3I
Wed Oct 17, 2018 6:40 pm
Forum: SI Units, Unit Conversions
Topic: How does grading for discussion posts work?
Replies: 80
Views: 2581

Re: How does grading for discussion posts work?

If we forget to do the 3 post one week, do we automatically loose those 3 points? Does anyone know if there is a way to gain them? Thank you!
by Imelda Mena 3I
Wed Oct 17, 2018 5:44 pm
Forum: Einstein Equation
Topic: 7th Edition 1B.15
Replies: 3
Views: 47

Re: 7th Edition 1B.15

I got it now! The energy of the photon that should be used to solve for wavelength in part c is in fact 2.25 x 10^-17J which is obtained from adding up the energy from part b (1.66 x 10^-17J) to the kinetic energy (1/2mv^2) of the electron. Once you do that you should get 2.25 x 10^-17J which is use...
by Imelda Mena 3I
Wed Oct 17, 2018 5:17 pm
Forum: Einstein Equation
Topic: 7th Edition 1B.15
Replies: 3
Views: 47

Re: 7th Edition 1B.15

I am having the same problem, I am getting 12nm for the wavelength instead of the 8.8nm that the solutions manual says. My answer for part b was 1.66x10^-17J, not 2.25x10^-17J. How did you get 2.25x10^-17J?
by Imelda Mena 3I
Wed Oct 17, 2018 5:07 pm
Forum: Einstein Equation
Topic: Units of Energy
Replies: 5
Views: 164

Re: Units of Energy

I personally always like to write out the SI units for Joules in order to make sure the units match with everything else and I am not using the wrong variable. However in terms of when you actually NEED to write out the SI units, I would say whenever the question asks you to, otherwise there is no n...
by Imelda Mena 3I
Wed Oct 17, 2018 4:45 pm
Forum: Einstein Equation
Topic: Energy Equations
Replies: 4
Views: 76

Re: Energy Equations

Hi, so just to clarify the v in the equation E=hv is not velocity but frequency?
by Imelda Mena 3I
Wed Oct 17, 2018 4:41 pm
Forum: Einstein Equation
Topic: 6th Edition Ch1.33B
Replies: 1
Views: 54

6th Edition Ch1.33B

Hey, can someone explain why (2.5x10^16 1/s) is used as the velocity and not the velocity that was given at the beginning of the problem (3.6x10^3 km/s)? Thank you in advance!
by Imelda Mena 3I
Mon Oct 15, 2018 5:59 pm
Forum: Einstein Equation
Topic: Einstein's Equation: E=hv
Replies: 11
Views: 339

Re: Einstein's Equation: E=hv

The variable h in this equation, as my classmates have said, is Planck's constant and it's equal to 6.626*10^(-34). It has units of [J*s] which can also be converted to [kg*m^(2)*s^(-1)]. It will be given to us on exams.
by Imelda Mena 3I
Sun Oct 07, 2018 3:11 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 116
Views: 10349

Re: All students read this sig fig post [ENDORSED]

I think when taking values from the period table it's safe to use 4 sig figs.
by Imelda Mena 3I
Wed Oct 03, 2018 5:09 pm
Forum: Student Social/Study Group
Topic: 5th Edition- Help Please
Replies: 1
Views: 77

Re: 5th Edition- Help Please

Turns out the 6th Edition is on reserve!
by Imelda Mena 3I
Wed Oct 03, 2018 4:23 pm
Forum: Student Social/Study Group
Topic: 5th Edition- Help Please
Replies: 1
Views: 77

5th Edition- Help Please

Hi! I have the 5th edition of the textbook but the page numbers are not provided for this version on the syllabus. Is the textbook not available for reserve at the library? Because I came to Powell but they only have the 5th edition textbook too! Can someone please help me ? I have discussion tomorr...
by Imelda Mena 3I
Sat Jan 24, 2015 2:04 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Ch.7 Question 51
Replies: 2
Views: 292

Re: Ch.7 Question 51

Alright, thanks again!
by Imelda Mena 3I
Sat Jan 24, 2015 1:51 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Ch.7 Question 51
Replies: 2
Views: 292

Ch.7 Question 51

I was wondering where they got the temperature change to be 298K, is this the standard temperature to use if the temperature is not given in the problem?
Thank you.

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