Search found 35 matches

by Rachel Kho Disc 1I
Sat Nov 21, 2020 9:28 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ground State vs. Excited State
Replies: 6
Views: 26

Ground State vs. Excited State

I’m having some trouble understanding ground state electron configurations versus excited state electron configurations. When looking at the orbital diagram, how are you able to tell the difference between the two? What exactly goes into the orbital diagram of an excited state electron? This concept...
by Rachel Kho Disc 1I
Sat Nov 21, 2020 9:18 pm
Forum: Lewis Structures
Topic: Central Atom Question
Replies: 20
Views: 70

Re: Central Atom Question

H will never be the central atom because as others stated before it can only form one bond, and additionally it's useful to put whatever atom has the lowest ionization energy as the central atom (this tactic doesn't work all the time but it is usually a good starting point).
by Rachel Kho Disc 1I
Sat Nov 21, 2020 9:15 pm
Forum: Electronegativity
Topic: Electronegativity difference
Replies: 8
Views: 38

Re: Electronegativity difference

I think it's important to remember that H is a weird case. Hydrogen bonds are such exceptionally strong cases of dipole-dipole bonds because there is a great electronegativity difference between H and the other atom, and the H must bond to N, O, and F which all have very high electronegativities. In...
by Rachel Kho Disc 1I
Sat Nov 21, 2020 9:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What are orbitals?
Replies: 10
Views: 61

Re: What are orbitals?

It might also be useful to note that in places where there are "blind spots", there is 0 electron density and an electron cannot be located in these areas. These places are called nodes, and there are two types: radial (spherical) and angular (angular). On a coordinate plane, these are whe...
by Rachel Kho Disc 1I
Sat Nov 21, 2020 8:38 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exercise 2A.5
Replies: 3
Views: 24

Exercise 2A.5

There are some electron configurations with [Xe]4f145d106s2. Where exactly is the 4f14 coming from? I thought it might be the lanthanides and actinides, but I counted 15 columns and not 14 columns, so I'm a little confused.
by Rachel Kho Disc 1I
Sun Nov 15, 2020 8:48 pm
Forum: Resonance Structures
Topic: Sapling #9 part b
Replies: 2
Views: 9

Re: Sapling #9 part b

I got answer D in response to this question, because if the experimental value is 144 pm which is close to the 140 average expected value for the Cl-O double bond, then there should be 4 double bonds. However, answer C (which has 3 double bonds and 1 single bond) is also correct because the feedback...
by Rachel Kho Disc 1I
Sun Nov 15, 2020 7:46 pm
Forum: Bond Lengths & Energies
Topic: Sapling #4
Replies: 4
Views: 30

Sapling #4

I'm not exactly sure what is meant by bond character in one of the parts to sapling 4? I eventually got to the right answer because by comparing the experimental bond lengths to the ones given in the table and deducing that because experimental single bonds are less than the expected, the double bon...
by Rachel Kho Disc 1I
Sun Nov 15, 2020 7:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #20
Replies: 12
Views: 39

Re: Sapling #20

A hydrogen bond is any bond wherein a hydrogen atom is bonded to another highly electronegative atom, namely N, O, or F. Even though a C-H bond has a hydrogen in it, a carbon-hydrogen bond is not considered a hydrogen bond because there isn't a huge difference in electronegativity between carbon and...
by Rachel Kho Disc 1I
Sun Nov 15, 2020 7:09 pm
Forum: Ionic & Covalent Bonds
Topic: midterm 2: knowing compounds
Replies: 14
Views: 46

Re: midterm 2: knowing compounds

I agree that we most likely wouldn't need to know nomenclature for the midterm, but I think it's still a good idea to at least be somewhat familiar with knowing polyatomic ions.
by Rachel Kho Disc 1I
Sun Nov 15, 2020 7:07 pm
Forum: Dipole Moments
Topic: Sapling #13
Replies: 8
Views: 34

Re: Sapling #13

Make sure you count the hydrogen bonds that are already in the urea molecule, because that's where I made a mistake. Initially, I only counted the hydrogen bonds that COULD form and so it took me a few tries to get to the right answer.
by Rachel Kho Disc 1I
Sun Nov 08, 2020 9:37 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Radial vs Angular Nodes
Replies: 2
Views: 26

Re: Radial vs Angular Nodes

You can visualize it on a coordinate plane by thinking that places where the wave crosses the axis is a node. There, you have a zero chance of finding an electron. Radial nodes are spherical and have zero electron density, whereas angular nodes are planar with zero electron density.
by Rachel Kho Disc 1I
Sun Nov 08, 2020 9:33 pm
Forum: Quantum Numbers and The H-Atom
Topic: Textbook 1D #21
Replies: 5
Views: 24

Re: Textbook 1D #21

A tip my TA gave me was super helpful in understanding the relationship between l and s,p,d,f orbitals. when l = 0 --> s when l = 1 --> p when l = 2 --> d when l = 3 --> f a) l = 2 corresponds to the d orbital. b) l = 0 corresponds to the s orbital. c) l = 2 corresponds to the d orbital. d) l = 3 co...
by Rachel Kho Disc 1I
Sun Nov 08, 2020 9:29 pm
Forum: Quantum Numbers and The H-Atom
Topic: Textbook 1D #13
Replies: 3
Views: 19

Re: Textbook 1D #13

A tip my TA gave me was super helpful! for l: l = 0 --> s l = 1 --> p l = 2 --> d l = 3 --> f for ml: l = 0 --> ml = 1 l = 1 --> ml = 3 l = 2 --> ml = 5 l = 3 --> ml = 7 a) given n = 7, values of l can be from 0 --> 6, which means that including 0 there are 7 possible values. b) given 6d, d correspo...
by Rachel Kho Disc 1I
Sun Nov 08, 2020 9:13 pm
Forum: Student Social/Study Group
Topic: midterm 1
Replies: 10
Views: 64

Re: midterm 1

It's also super helpful to just drill the homework problems! Make sure you are able to complete the homework correctly without looking at your notes. The solutions should be on Sapling under Atkins 7e SSM.
by Rachel Kho Disc 1I
Sun Nov 08, 2020 9:10 pm
Forum: Properties of Light
Topic: Is c always the speed of light?
Replies: 70
Views: 232

Re: Is c always the speed of light?

Yes, c is a constant equal to 3*10^8 m/s, and it is commonly used in equations c=(lambda)(nu)...in other words, wavelength*frequency. Another side note: the speed of light is lower case c. Please do not confuse it with C as in Celsius or C as in carbon!
by Rachel Kho Disc 1I
Sun Nov 01, 2020 10:54 pm
Forum: Quantum Numbers and The H-Atom
Topic: Sapling #21
Replies: 4
Views: 21

Sapling #21

The question is: how many electrons in an atom can have these sets of quantum numbers?

I was able to get the answers, but I'm having trouble with understanding why there are 14 electrons if n=5 and l=3. Would someone be able to help me out? Thanks!
by Rachel Kho Disc 1I
Sun Nov 01, 2020 10:51 pm
Forum: DeBroglie Equation
Topic: Sapling #25
Replies: 4
Views: 26

Re: Sapling #25

For energy of a photon, use E=hv and c=v(lambda). Then for the energy of an electron, use E=1/2mv^2. Don't forget to convert micrometers to meters because I absolutely made that mistake a couple of times! (1 micrometer=1*10^-6m).
by Rachel Kho Disc 1I
Sun Nov 01, 2020 10:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Sapling #8 week2-4
Replies: 5
Views: 23

Re: Sapling #8 week2-4

To isolate lambda, you multiply both sides by lambda so that eventually you'll get lambda = 1/(1.0974*10^7 m/s)((1/nf^2)-(1/ni^2). From there, you should be getting the answer in meters which you can then convert to nanometers.
by Rachel Kho Disc 1I
Sun Nov 01, 2020 10:28 pm
Forum: Trends in The Periodic Table
Topic: sapling #23
Replies: 6
Views: 19

Re: sapling #23

I'm also having trouble with this, because I got the first part of the answer correct but I don't know what I'm doing wrong for the second part. When I ask for hints, it says that I need to use conversions of eV to 1.602*10^-22 kJ, and then also Avogadro's number. Then once you have that answer, you...
by Rachel Kho Disc 1I
Sun Nov 01, 2020 9:40 pm
Forum: Photoelectric Effect
Topic: Sapling Homework #6
Replies: 3
Views: 26

Sapling Homework #6

The question reads: When a metal was exposed to photons at a frequency of 1.45×1015 s−1, electrons were emitted with a maximum kinetic energy of 3.70×10−19 J. Calculate the work function, Φ, of this metal. What is the maximum number of electrons that could be ejected from this metal by a burst of ph...
by Rachel Kho Disc 1I
Sun Oct 25, 2020 9:10 pm
Forum: Molarity, Solutions, Dilutions
Topic: mmol
Replies: 14
Views: 114

Re: mmol

mmol means millimole. If you want to convert it to moles, just multiply the amount of mmol by 10^-3. Also, think of it this way: don't let the fact that the base unit is a mol. Just remember the King Henry Died By Drinking Chocolate Milk acronym and use it to multiply or divide by 10^n when necessa...
by Rachel Kho Disc 1I
Sun Oct 25, 2020 8:53 pm
Forum: *Shrodinger Equation
Topic: Hamiltonian
Replies: 3
Views: 29

Hamiltonian

Can anyone explain why the Hamiltonian is a double derivative? I remember learning and understanding it during lecture but as I'm looking back over my lecture notes I'm forgetting what was meant by that.
by Rachel Kho Disc 1I
Sun Oct 25, 2020 8:45 pm
Forum: Properties of Light
Topic: Midterm Conceptual Questions
Replies: 5
Views: 50

Midterm Conceptual Questions

Does anyone know any examples of possible concept questions that they'll ask on the midterm? Or does anyone have access to a worksheet of concept questions for practice? Thanks!
by Rachel Kho Disc 1I
Sun Oct 25, 2020 8:36 pm
Forum: Administrative Questions and Class Announcements
Topic: Step Up Sessions
Replies: 71
Views: 4362

Re: Step Up Sessions

Also are all UA peer-learning and TA office hours happening as usual for this week or are they cancelled because it is a midterm week?
by Rachel Kho Disc 1I
Sun Oct 25, 2020 8:28 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Advice for studying
Replies: 92
Views: 1928

Re: Advice for studying

Get as much practice in as possible! You can find extra problems in the textbook, sapling, UA peer-learning sessions, etc. If there is a difficult concept, you can go to office hours or even watch a video on YouTube.
by Rachel Kho Disc 1I
Sun Oct 18, 2020 8:40 pm
Forum: Properties of Light
Topic: Units to know
Replies: 4
Views: 18

Re: Units to know

You probably don't really need to memorize units, but it would probably be helpful to at least be quick with the units that Professor Lavelle gave us in lecture so that you save time when you're taking a test. From my notes, he gave us giga (10^9), mega (10^6), kilo (10^3), deci (10^-1), centi (10^-...
by Rachel Kho Disc 1I
Sun Oct 18, 2020 8:34 pm
Forum: Student Social/Study Group
Topic: Midterm
Replies: 7
Views: 25

Re: Midterm

I also find attending UA peer review sessions really effective. The undergraduate assistants are also students who have taken this course in the past so they're able to explain difficult concepts pretty well. The workshop sessions have worksheets of extra problems to go over so you get the practice ...
by Rachel Kho Disc 1I
Sun Oct 18, 2020 7:22 pm
Forum: Significant Figures
Topic: Sig Figs and Zeroes
Replies: 5
Views: 41

Sig Figs and Zeroes

I always have trouble with determining significant figures when zeroes are involved, either before or after the decimal place. Does anyone have any concise or definite rules about how to deal with zeroes in sig figs?
by Rachel Kho Disc 1I
Sun Oct 18, 2020 7:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Respondus
Replies: 3
Views: 28

Re: Respondus

My TA sent a whole list of instructions, but basically: 1. You download the respondus. Maybe there's a site where you can do that but my TA had a url on his TA site. 2. Launch the lockdown browser. 3. On the pop-up, press open lockdown browser 4. There should be another pop-up, so press close applic...
by Rachel Kho Disc 1I
Sun Oct 18, 2020 6:58 pm
Forum: General Science Questions
Topic: External Webcam/Exam procedure
Replies: 4
Views: 31

Re: External Webcam/Exam procedure

If you don't want to buy an external webcam, my TA also mentioned there's a possibility that you could use another computer device if one is available to you! Maybe if you have a desktop computer at home, you can use that to proctor the exam and then use your laptop's webcam to record your workspace.
by Rachel Kho Disc 1I
Sun Oct 11, 2020 3:42 pm
Forum: Balancing Chemical Reactions
Topic: Balancing equations.
Replies: 35
Views: 597

Re: Balancing equations.

I also am confused about balancing equations that have polyatomic ions? For example I know this is supposed to be balanced already: 3 Pb(NO3)2 + 2 Na3PO4 --> Pb3(PO4)2 + 6 NaNO3 But I'm not sure how that can be when there aren't any parentheses around the second molecule in the reactants and the sec...
by Rachel Kho Disc 1I
Sun Oct 11, 2020 2:56 pm
Forum: Limiting Reactant Calculations
Topic: Question 10 homework
Replies: 9
Views: 122

Re: Question 10 homework

Hi, trying to understand how the strucure creates the molecular mass, I'm thinking each vertex represents one carbon plus an additional hydrogen if not already bonded to another distinct molecule? So using this information, could add the mass of carbon and hydrogen for each vertex since the carbons...
by Rachel Kho Disc 1I
Sun Oct 11, 2020 2:37 pm
Forum: Empirical & Molecular Formulas
Topic: Molecular Compound
Replies: 3
Views: 38

Re: Molecular Compound

My TA told me that's not necessary because the class is more about applying concepts and formulas, but I think it would be good to know the common polyatomic ions!
by Rachel Kho Disc 1I
Sun Oct 11, 2020 2:34 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Calculating Molar Mass (Sapling Week 1 #10)
Replies: 6
Views: 75

Re: Calculating Molar Mass (Sapling Week 1 #10)

Another good visualization tactic is to draw out the molecule! There is a carbon at each "kink" in the molecule, so for 2-butanone there are 4 carbon atoms. Each carbon atom has to have 4 bonds, and you can fulfill this quota by attaching hydrogen atoms which only require 1 bond to each ca...
by Rachel Kho Disc 1I
Sat Oct 10, 2020 7:39 pm
Forum: Limiting Reactant Calculations
Topic: Question 10 homework
Replies: 9
Views: 122

Re: Question 10 homework

For this question, do we need to know the chemical formula 2-butanone and 3-methyl-3-hexanol in order to solve this question? And if we did, would we just search up what the chemical formula is if we didn't know beforehand? You would only need to know the formula so that you could figure out the mo...

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