## Search found 50 matches

Thu Dec 03, 2020 4:49 pm
Forum: Naming
Topic: Formula Order
Replies: 4
Views: 17

### Re: Formula Order

I don't think the order matters when writing the formula as long as the TM is first and the ligands follow. However, the order is alphabetical when writing the name!
Thu Dec 03, 2020 2:49 pm
Forum: Naming
Topic: Chem 14BL question
Replies: 1
Views: 11

### Re: Chem 14BL question

I think most people suggest taking 14BL after 14B but I have a friend who took both simultaneously and said it was very doable!
Thu Dec 03, 2020 2:20 pm
Forum: Hybridization
Topic: Textbook problem 2.45 part b).
Replies: 1
Views: 17

### Textbook problem 2.45 part b).

2.45 Consider the bonding in H2C=CHCHO. (a) Draw the most important Lewis structure. Include all nonzero formal charges. (b) Identify the composition of the bonds and the hybridization of each lone pair -- for example, by writing sigma(H1s, C2sp^2) Hi! I am confused about how to write the compositio...
Wed Dec 02, 2020 8:41 pm
Forum: Naming
Topic: 9C 1 part c
Replies: 6
Views: 27

### Re: 9C 1 part c

Name each of the following complex ions and identify the oxidation number of the metal. C. [Co(CN)5(OH2)]2- Could someone explain how to name this. So usually I first look at the TM which in this case is Co (TM listed first). Since the overall charge is 2-, the charge of Co has to be +3 (CN is 1- a...
Wed Dec 02, 2020 8:35 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: [Pt(en)Cl2] coordination number
Replies: 2
Views: 14

### Re: [Pt(en)Cl2] coordination number

Could someone help me figure out the coordination number of [Pt(en)Cl2] and explain why it is not 2? I thought that the number of bonds is equal to the coordination number. Is that not true in this case? Also, what does the en indicate? Thanks! Hi! the en signifies ethylenediamine which is NH2CH2CH...
Sun Nov 29, 2020 10:45 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling HW #18
Replies: 7
Views: 44

### Re: Sapling HW #18

When they ask about relative positions, I think they are talking about the positions of atoms in relation to one another in a 3D space, using the lewis structure to help create the model. Lewis structures are 2D, but the actual model of the molecule is in 3D. For instance, the lewis structure for C...
Tue Nov 24, 2020 1:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Ways to remember VSEPR
Replies: 6
Views: 57

### Re: Ways to remember VSEPR

I usually just think of it as a word rather than the 5 letters so I say it like Vespr which is in the wrong order for the acronym so I make sure to remain cognitive of that! Not sure if this makes a ton of sense but I hope it's a little bit helpful!
Tue Nov 24, 2020 1:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook question 2E.1
Replies: 2
Views: 12

### Textbook question 2E.1

2E.1 Below are ball-and-stick models of two molecules. In each case, indicate whether there must be, may be, or cannot be one or more lone pairs of electrons on the central atom. ￼￼ Why isn't the answer for part b "cannot be one or more lone pairs"? If the bond angle is 180 degrees doesn't...
Tue Nov 24, 2020 1:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape vs. Electron Arrangement
Replies: 4
Views: 25

### Shape vs. Electron Arrangement

I am a little bit confused about how to tell when we are supposed to give the shape of the electron arrangement of the molecule. Is there a "default"? I also get confused with whether we account for lone pairs when giving shape or electron arrangement. If anyone could help explain this, I'...
Tue Nov 24, 2020 1:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Angular Molecular Shape
Replies: 3
Views: 19

### Angular Molecular Shape

The textbook uses the name angular to describe molecular shape but is angular the same as bent? Or if not, what is the difference between bent and angular?
Wed Nov 18, 2020 6:23 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Number of Hydrogen Bond Sites on Guanine
Replies: 1
Views: 13

### Re: Number of Hydrogen Bond Sites on Guanine

There are 3 H-bonds in a GC pair and 2 h-bonds in an AT pair! Hope this helps!
Tue Nov 17, 2020 7:33 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Intermolecular size vs Intramolecular size
Replies: 2
Views: 16

### Re: Intermolecular size vs Intramolecular size

For stronger intermolecular forces are you looking for the larger molecule because it has more electrons=stronger bonds while for intramolecular forces you would look for the smaller molecule so it can be pulled in closer? I believe that if we're talking about intermolecular forces you'd be analyzi...
Tue Nov 17, 2020 12:02 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability and Polarizing Power
Replies: 5
Views: 24

### Re: Polarizability and Polarizing Power

In addition to what everyone else said, I find it really helpful to just know that polarizing power is related to cations and polarizability is related to anions!
Tue Nov 17, 2020 11:59 am
Forum: Lewis Structures
Topic: Most stable/ resonance structure
Replies: 3
Views: 10

### Re: Most stable/ resonance structure

I believe when we draw resonance structures we are already drawing the most stable structure according to the formal charges!
Tue Nov 17, 2020 11:58 am
Forum: Ionic & Covalent Bonds
Topic: Covalent molecule - polarizability and en
Replies: 2
Views: 9

### Re: Covalent molecule - polarizability and en

Hi! By draw do you mean drawing the Lewis Structure? I think the molecule is covalent because the difference in electronegativity between Al and Cl is not very significant.
Tue Nov 17, 2020 11:40 am
Forum: Lewis Structures
Topic: Determining Polar or Non-Polar from Lewis Structure
Replies: 3
Views: 17

### Re: Determining Polar or Non-Polar from Lewis Structure

hello! In some cases, we may be given the electronegativity values and we compare them to see whether or not the bond is polar or non-polar. Otherwise, we may need to just simply compare the polarity of two compounds. For example, we may be asked between HF and HI is more polar. Since I is less ele...
Tue Nov 17, 2020 11:22 am
Forum: Lewis Structures
Topic: Determining Polar or Non-Polar from Lewis Structure
Replies: 3
Views: 17

### Determining Polar or Non-Polar from Lewis Structure

Hi everyone! I was wondering if anyone knows if there's a "threshold" or anything to determine whether a molecule is polar or non-polar from the Lewis Structure. I know that if an element is very electronegative compared to the other element, there will be a partial negative on the more el...
Thu Nov 12, 2020 5:00 pm
Forum: Bond Lengths & Energies
Topic: Increasing strengths of dispersion forces
Replies: 2
Views: 12

### Re: Increasing strengths of dispersion forces

I am also unsure about this. I believe it has something to do with polarizability? Br and I are both larger than F and Cl so they have a larger/more easily distorted electron cloud and higher polarizability. I'm not sure if I have the correct thought process so if anyone knows, I'd really appreciate...
Thu Nov 12, 2020 4:10 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 6
Views: 41

### Re: Polarizability

FionaHunter21 wrote:Between two anions in the same row, would an anion with a -2 charge be more or less polarizable than an anion with a -1 charge?

I think it is just by anion size. So whichever one is larger will be more polarizable even if the charge is a smaller magnitude. Someone, please correct me if I am wrong!
Wed Nov 11, 2020 12:46 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook Question 2A.5 part a)
Replies: 1
Views: 14

### Textbook Question 2A.5 part a)

Give the ground-state electron configuration expected for each of the following ions: (a) Cu+ For this question I got the ground-state electron configuration of Cu: [Ar] 3d^9 4s^2 and then when I took the positive charge into account I got Cu+: [Ar] 3d^9 4s^1. Can anyone explain why this is incorrect?
Wed Nov 11, 2020 12:44 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: F-block?
Replies: 7
Views: 29

### F-block?

A UA mentioned that we don't need to know how to write electron configurations involving the f-block however I have noticed that some of the assigned textbook questions involve the f-block. Does anyone know if this a mistake/if I should skip these questions? Or should I learn how to do it/ will we b...
Wed Nov 11, 2020 12:39 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook Question 2A.21 part D)
Replies: 2
Views: 12

### Textbook Question 2A.21 part D)

Give the ground-state electron configuration and number of unpaired electrons expected for each of the following ions: (a) Ca2+; (b) In+; (c) Te2−; (d) Ag+ I am a little bit confused about part d. I got the configuration for Ag+: [Kr]4d^9 5s^2 and then since it's plus 1 I thought it would be Ag+: [K...
Sun Nov 08, 2020 2:49 pm
Forum: General Science Questions
Topic: Enrolling in Chem 14B and BL simultaneously?
Replies: 10
Views: 93

### Re: Enrolling in Chem 14B and BL simultaneously?

I have a friend who is in 14b and 14bl right now and she says it is very doable so I would do whatever works best with your schedule!
Sun Nov 08, 2020 2:19 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook question 2A.9 (omit c and d)
Replies: 2
Views: 14

### Textbook question 2A.9 (omit c and d)

2A.9 Which M2+ ions (where M is a metal) are predicted to have the following ground-state electron configurations: (a) [Ar]3d7; (b) [Ar]3d6; (c) [Kr]4d4; (d) [Kr]4d3?

I am a little bit confused about what this question is asking for, does anyone know how to start/ interpret the question?
Wed Nov 04, 2020 6:11 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Removing Electrons from orbitals
Replies: 4
Views: 39

### Removing Electrons from orbitals

Hi everyone, could anyone explain how they understand or interpret questions that ask which orbital an electron would be removed from to create a +1 ion? I'm a bit confused because I originally assumed it would be removed from the orbital with the e- found furthest from the nucleus.
Wed Nov 04, 2020 5:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.13 part (e) Tungsten electron configuration
Replies: 2
Views: 16

### Re: 1E.13 part (e) Tungsten electron configuration

I just realized we are supposed to omit (e) so please disregard this!
Wed Nov 04, 2020 5:51 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.13 part (e) Tungsten electron configuration
Replies: 2
Views: 16

### 1E.13 part (e) Tungsten electron configuration

Write the ground-state electron configuration for each of the following atoms: (e) tungsten Could anyone explain how to write the ground-state electron configuration for W? I know it begins with [Xe] however I don't understand how to write the correct configuration and am specifically struggling wit...
Tue Nov 03, 2020 1:42 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook question 1E.13 part A
Replies: 3
Views: 16

### Textbook question 1E.13 part A

Write the ground-state electron configuration for each of the following atoms: (a) silver

Can anyone explain why the electron configuration for silver isn't [Kr]5s^2 2d^9?
Tue Oct 27, 2020 4:55 pm
Forum: DeBroglie Equation
Topic: UA Session: Wavelength of the ejected electron
Replies: 2
Views: 42

### UA Session: Wavelength of the ejected electron

If the wavelength of incident light on sodium metal was 810 nm, and the work function of sodium is 1.1 eV, what is the wavelength of the ejected electron? I converted the wavelength and work function to SI units. I then found the frequency and used that to find the energy of the photon (2.45x10^-19)...
Tue Oct 27, 2020 12:02 pm
Forum: DeBroglie Equation
Topic: UA Matthew Tran worksheet: Question 5
Replies: 1
Views: 33

### UA Matthew Tran worksheet: Question 5

5. (10 min) Light of wavelength 346 nm is shone on the surface of sodium, and the velocity of the ejected electrons is measured to be 6.73 x 105 m/s. What is the work function of sodium in eV? I am confused about this question because I'm not sure what equations to use. I was planning on using 1/2 m...
Tue Oct 27, 2020 11:44 am
Forum: Photoelectric Effect
Topic: UA Workshop: Question 4 part b
Replies: 1
Views: 21

### UA Workshop: Question 4 part b

4. Zinc metal has a work function of 6.89 x 10-19 J. a. If UV light with a wavelength of 122 nm is shone on the zinc, what is the kinetic energy of the emitted electrons? b. What is the longest wavelength of light that will eject an electron from zinc? What is the smallest frequency of light that wi...
Mon Oct 26, 2020 9:58 pm
Forum: Properties of Light
Topic: Tips for knowing what equation to use?
Replies: 5
Views: 51

### Tips for knowing what equation to use?

I noticed I have been struggling with identifying which equations to use and when (specifically when to use c=lambda(frequency), E=h(frequency), or De Broglie's). Does anyone have any tips or would be willing to share how they interpret problems and decide when to use what equation?
Mon Oct 26, 2020 4:39 pm
Forum: Properties of Light
Topic: Practice Question #6: The work function for lithium is 4.6x10^-19 J.
Replies: 2
Views: 28

### Practice Question #6: The work function for lithium is 4.6x10^-19 J.

6. The work function for lithium is 4.6x10^-19 J. a) What is the lowest frequency of light that will cause photoelectric emission? b) What is the maximum energy of electrons emitted when light of 7.3x10^14 Hz is used? I understand part a and got the correct answer; however for part b I keep getting ...
Fri Oct 23, 2020 2:33 pm
Forum: General Science Questions
Topic: Sapling
Replies: 3
Views: 26

### Re: Sapling

I don't think the order is fixed but I just skipped all the questions involving quantum numbers and ended up answering 18 questions that I know we have covered in lectures!
Thu Oct 22, 2020 5:21 pm
Forum: Properties of Light
Topic: Sapling Question Randomization
Replies: 1
Views: 28

### Sapling Question Randomization

Does anyone know how to turn off Sapling's randomization of the questions? I know Dr. Lavelle mentioned we should do this in one of his recent emails but I cannot figure out how and some questions before #19 involve material that we have not covered yet.
Thu Oct 22, 2020 4:39 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Problem 1D.11
Replies: 1
Views: 12

### Problem 1D.11

1D.11 How many orbitals are in subshells with l equal to (a) 0; (b) 2; (c) 1; (d) 3?

What does l refer to in this problem?
Thu Oct 22, 2020 4:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Practice Problems in Outline 2
Replies: 2
Views: 24

### Re: Practice Problems in Outline 2

I think you are right as well! However, I was a little bit confused because I feel like the majority of 1D.2 covers information that wasn't covered in the lecture?
Wed Oct 21, 2020 8:29 pm
Forum: DeBroglie Equation
Topic: 1B.15 part b and c.
Replies: 3
Views: 43

### 1B.15 part b and c.

The velocity of an electron that is emitted from a metallic surface by a photon is 3.6×10^3 km⋅s−1. (a) What is the wavelength of the ejected electron? (b) No electrons are emitted from the surface of the metal until the frequency of the radiation reaches 2.50×10^16 Hz. How much energy is required t...
Wed Oct 21, 2020 2:11 pm
Forum: Properties of Light
Topic: MHz to Hz 1A.9
Replies: 3
Views: 34

### MHz to Hz 1A.9

A college student recently had a busy day. Each of the student’s activities on that day (reading, getting a dental x-ray, making popcorn in a microwave oven, and acquiring a suntan) involved radiation from a different part of the electromagnetic spectrum. Complete the following table and match each ...
Sun Oct 18, 2020 4:05 pm
Forum: Balancing Chemical Reactions
Topic: Textbook Problem H.11
Replies: 1
Views: 23

### Textbook Problem H.11

In one stage in the commercial production of iron metal in a blast furnace, the iron(III) oxide, Fe2O3, reacts with carbon monoxide to form solid Fe3O4 and carbon dioxide gas. In the second stage, the Fe3O4 reacts further with carbon monoxide to produce solid elemental iron and carbon dioxide. Write...
Sat Oct 17, 2020 2:37 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Fundamentals Textbook Homework E.23 part D
Replies: 1
Views: 30

### Fundamentals Textbook Homework E.23 part D

Calculate the amount (in moles) of (d) H2O in 2.00 g of Na2CO3⋅10H2O For this question, I found the molar mass of Na2CO3⋅10H2O to be 19100 g. mol^-1. I divided 2g by this molar mass to get 1.05x10^-4 moles Na2CO3⋅10H2O. I then multiplied this by 10 because there are 10 (molecules?) of H2O to get 0.0...
Thu Oct 15, 2020 5:57 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: WK 2 Sapling #5
Replies: 4
Views: 54

### Re: WK 2 Sapling #5

Adding on to what Tamara and Hannah explained, make sure to convert your calculated wavelength from m to nm by diving by 10^-9. I forgot to do this originally and kept getting the incorrect answer.
Thu Oct 15, 2020 5:35 pm
Forum: Photoelectric Effect
Topic: Sapling Homework Q4 part b
Replies: 3
Views: 27

### Re: Sapling Homework Q4 part b

I got the right answer now, thank you! I did not realize that I was supposed to divide the total energy by the work function I initially solved for.
Thu Oct 15, 2020 5:20 pm
Forum: Photoelectric Effect
Topic: Sapling Homework Q4 part b
Replies: 3
Views: 27

### Sapling Homework Q4 part b

When a metal was exposed to photons at a frequency of 1.43×1015 s−1, electrons were emitted with a maximum kinetic energy of 3.70×10−19 J. a. Calculate the work function, Φ, of this metal. b. What is the maximum number of electrons that could be ejected from this metal by a burst of photons (at some...
Mon Oct 12, 2020 7:27 pm
Forum: Student Social/Study Group
Topic: Clarification on buying an external webcam
Replies: 5
Views: 76

### Clarification on buying an external webcam

Hi everyone,
I didn't know where else to ask this question but did anyone else receive an email from their TA about needing to get an external webcam (one that can be plugged into a computer)? I just want to clarify if this is necessary before buying one.
Thu Oct 08, 2020 6:20 pm
Forum: Student Social/Study Group
Topic: STEM clubs
Replies: 8
Views: 91

### Re: STEM clubs

A great way to sort through all the STEM (and every other club) is to check out the @uclaeaf Instagram! They just highlighted every club on their page with details, application deadlines, and such.
Thu Oct 08, 2020 3:46 pm
Forum: Molarity, Solutions, Dilutions
Topic: Sapling Week 1 HW_problem #9
Replies: 9
Views: 108

### Re: Sapling Week 1 HW_problem #9

I am also having trouble finding the empirical formula for this question. I wrote out the chemical reaction as C_H_O_ + O2 --> CO2 + H2O because I believe "burning" is the same as combustion. From there I calculated the moles of CO2 and H2O, but I don't know what my next step should be. An...
Thu Oct 08, 2020 3:16 pm
Forum: Molarity, Solutions, Dilutions
Topic: A solution of CaCl2 in water forms a mixture that is 41.5% calcium chloride by mass. If the total mass of the mixtur
Replies: 4
Views: 32

### A solution of CaCl2 in water forms a mixture that is 41.5% calcium chloride by mass. If the total mass of the mixtur

Hi everyone, I am confused about the Sapling week 1 homework, question 7, and was wondering if anyone could walk me through how to solve it. The question is as follows: A solution of CaCl2 in water forms a mixture that is 41.5% calcium chloride by mass. If the total mass of the mixture is 986.6 g, w...
Thu Oct 08, 2020 3:02 pm
Forum: Significant Figures
Topic: Sapling HW #4
Replies: 31
Views: 245

### Re: Sapling HW #4

Hi! Looking at the explanation for this question really helped me because it explained that all non-zero digits are significant, that zeroes between 2 non-zero digits are significant, and that trailing zeroes are not significant if there is no decimal point showing. So 950000 has only two sig figs a...
Thu Oct 08, 2020 2:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 226
Views: 116432

### Re: Advice from a Medical Student[ENDORSED]

Thank you for posting and sharing this. It is very motivating hearing how important this class and material is not just now, but in the future as well.