Search found 47 matches

by Megan Sparrow 1G
Mon Nov 23, 2020 6:19 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14BL
Replies: 1
Views: 21

Re: Chem 14BL

I haven't heard about Chem BL in terms of the waitlist, but since it is considered a lab, I think it would be more difficult to get in. If you don't get in this quarter, I know a lot of people are trying to do 14BL with Chem 14C for the spring quarter, since you already learned the topics from the p...
by Megan Sparrow 1G
Mon Nov 23, 2020 6:16 pm
Forum: Hybridization
Topic: Carbon rotation and breaking of bonds
Replies: 3
Views: 11

Re: Carbon rotation and breaking of bonds

In addition to what Katarina said, when a double bond breaks, pi bonds will always break first. Pi bonds are weaker than sigma bonds. This is because sigma bonds have head-on overlapping while pi bonds only have lateral overlapping. On the other hand, the electron density is more spread out in pi bo...
by Megan Sparrow 1G
Mon Nov 23, 2020 6:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Unconventional bond angles
Replies: 2
Views: 8

Re: Unconventional bond angles

Based on Dr. Lavelle's Outline 4 (Molecular Shape and Structure), the only part that specifically references bond angles is below: - Explain why lone pairs are more likely to found in certain locations around a central atom and how and why they affect the bond angles in a molecule, cation, or anion....
by Megan Sparrow 1G
Mon Nov 23, 2020 1:19 pm
Forum: Sigma & Pi Bonds
Topic: Double bond- second one is pi
Replies: 2
Views: 27

Re: Double bond- second one is pi

Sigma and pi bonds are chemical covalent bonds that are formed by the overlap of atomic orbitals. Sigma bonds are formed by end-to-end overlapping and Pi bonds are when the lobe of one atomic orbital overlaps another. Double and triple bonds are comprised of sigma bonds between hybridized orbitals a...
by Megan Sparrow 1G
Mon Nov 23, 2020 1:15 pm
Forum: Hybridization
Topic: Lack of Spin Pairing in Hybridized Orbitals
Replies: 2
Views: 29

Re: Lack of Spin Pairing in Hybridized Orbitals

During hybridization, the C-C sigma bond is formed when one sp orbital overlaps from each of the carbons, and two C-H bonds are created when the second sp orbital on each carbon overlaps with 1s orbital of hydrogen. In this, the carbon atom will have two half-filled 2p orbitals. These two pairs of p...
by Megan Sparrow 1G
Mon Nov 23, 2020 1:09 pm
Forum: Hybridization
Topic: Unhybridized Orbitals in pi Bonds
Replies: 1
Views: 23

Re: Unhybridized Orbitals in pi Bonds

To answer the first part of your questions, in inorganic chemistry, π bonds can be made from both p- and/or d-orbitals. As long as there is a general overlapping of the electron-dense regions, a pi bond can be formed. The diagram below shows different examples.
by Megan Sparrow 1G
Mon Nov 23, 2020 1:05 pm
Forum: Hybridization
Topic: Energy Level of sp3d and sp3d2
Replies: 2
Views: 24

Re: Energy Level of sp3d and sp3d2

After hybridization, all four hybrid orbitals have the same energy, lower than p orbitals, but higher than s orbitals. In terms of d orbitals, this website might help explain a bit more. http://butane.chem.uiuc.edu/cyerkes/Chem102AEFa07/Lecture_Notes_102/Lecture%2015'-102.htm#:~:text=Hybridization%2...
by Megan Sparrow 1G
Mon Nov 16, 2020 12:30 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: Polarizability
Replies: 3
Views: 26

Re: Polarizability

All molecules are polarizable to some extent. Polarizability affects dispersion forces in the following ways: As polarizability increases, the dispersion forces also become stronger. The relationship between polarizability and the factors of electron density, atomic radii, and molecular orientation....
by Megan Sparrow 1G
Mon Nov 16, 2020 12:08 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: Ion-Dipole vs Hydrogen Bonding
Replies: 3
Views: 23

Re: Ion-Dipole vs Hydrogen Bonding

The general order you listed is correct. I believe for this course and the tests, this is what we need to know. It is based on general trends we can find using a periodic table and given information.
by Megan Sparrow 1G
Mon Nov 16, 2020 10:53 am
Forum: Trends in The Periodic Table
Topic: Why don't other np4 elements behave like oxygen in terms of ionization?
Replies: 2
Views: 22

Re: Why don't other np4 elements behave like oxygen in terms of ionization?

The other group 16 elements that follow this trend include O, S, and Se. The other group 16 elements get too large for the ionization energy to reflect this change going down. This photo shows the energies of the first ionization energy.
by Megan Sparrow 1G
Mon Nov 16, 2020 10:43 am
Forum: Bond Lengths & Energies
Topic: F2 Bond Strength
Replies: 6
Views: 26

Re: F2 Bond Strength

Hello! If you are comparing the bond strength of diatomic halogens, we can compare F2 to Cl2. The bond dissociation energy of F2 is less than Cl2 because fluorine has a high electronegativity, resulting in F−F repelling each other and having lesser bond dissociation enthalpy than Cl2 since Cl is les...
by Megan Sparrow 1G
Mon Nov 16, 2020 10:37 am
Forum: Lewis Structures
Topic: "Plausible" Lewis Structures
Replies: 7
Views: 21

Re: "Plausible" Lewis Structures

The most plausible resonance structure is the one that is most stable. For example, the greater the number of covalent bonds, the greater the stability since more atoms will have complete octets. Also, the structure with the least number of formal charges and the least separation of formal charge is...
by Megan Sparrow 1G
Mon Nov 16, 2020 10:33 am
Forum: Determining Molecular Shape (VSEPR)
Topic: SO3 Structure
Replies: 4
Views: 28

Re: SO3 Structure

In this case, the reason that SO3^-2 is a trigonal pyramidal shape is due to only 3 of the 4 bonding positions are being occupied by atoms, when using 3 single bonds and a lone pair. The main difference is the bond angles. The reason it couldn't be trigonal planar is that a molecule with that format...
by Megan Sparrow 1G
Mon Nov 09, 2020 12:12 pm
Forum: Lewis Structures
Topic: interactions between ions
Replies: 1
Views: 39

Re: interactions between ions

I'm not sure if this is what you meant, but the energy released is found experimentally. It will always be given on Dr.Lavelle's test. In today's lecture (11/09), he noted that he found these values online and didn't personally calculate it. You could experimentally find the energy via calorimetry r...
by Megan Sparrow 1G
Mon Nov 09, 2020 10:44 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Which has more ionic character?
Replies: 11
Views: 43

Re: Which has more ionic character?

For anions, the larger the ionic radius of an anion, the greater its likelihood of being polarised is (the greater its polarisability). This is because the outer electrons are more loosely held by the nucleus (weaker electrostatic force of attraction due to greater distance from the nucleus). In ter...
by Megan Sparrow 1G
Mon Nov 09, 2020 10:13 am
Forum: Octet Exceptions
Topic: SO42- Octet Rule Exception Orbitals
Replies: 4
Views: 29

Re: SO42- Octet Rule Exception Orbitals

I believe you are on the right path in terms of 4s orbital filling first since it has lower energy compared to 3d orbitals. I'm not too sure about the covalent bonding aspect, but this problem and explanation I found online might help explain a bit.
by Megan Sparrow 1G
Mon Nov 09, 2020 10:09 am
Forum: Resonance Structures
Topic: lower energy vs higher energy
Replies: 3
Views: 32

Re: lower energy vs higher energy

Hey! To answer your question, I believe that all resonance structures technically contribute to the overall structure, but the major resonance contributor has the lowest energy. When the formal charge is 0 or close to 0, then the structure is most stable. In general, the most stable structures (lowe...
by Megan Sparrow 1G
Mon Nov 09, 2020 10:05 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Does polarizability increase left to right?
Replies: 4
Views: 31

Re: Does polarizability increase left to right?

Generally, polarizability increases as the volume occupied by electrons increases. On rows of the periodic table, polarizability decreases from left to right (larger molecules are more polarizable than smaller ones). Polarizability increases down on columns of the periodic table. I hope this helps!
by Megan Sparrow 1G
Tue Nov 03, 2020 2:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: practice problems
Replies: 1
Views: 26

Re: practice problems

An excited state means that, typically, the valence electron has moved from its ground state orbital ( lowest available energy) to some other higher energy orbital. So any electron configuration in which the last electron (the valence electron) is in a higher energy orbital, this element is said to ...
by Megan Sparrow 1G
Tue Nov 03, 2020 2:08 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Textbook question 1E.13 part A
Replies: 3
Views: 16

Re: Textbook question 1E.13 part A

Silver would have 47 electrons as long as it is in a neutral state. It is easy to assume that the configuration is [Kr]5s^2 2d^9, however you have to be careful with silver because it is a transition metal. This implies that the occupied d-orbitals are actually lower in energy than the s-orbitals th...
by Megan Sparrow 1G
Tue Nov 03, 2020 9:16 am
Forum: Lewis Structures
Topic: Resonance Energy
Replies: 1
Views: 18

Re: Resonance Energy

In terms of bond length and the stability of a molecule, the measures are directly proportional. When the bond order is higher, the bond length is shorter. A shorter bond length means that the bond is held tighter to the other atoms in a molecule, and it would require more energy to remove them comp...
by Megan Sparrow 1G
Mon Nov 02, 2020 3:05 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Psi in the Equation
Replies: 3
Views: 29

Re: Psi in the Equation

For the Heisenberg equation, we haven't used psi I believe. Psi is used in Schrodinger's equation and represents the wave function. Psi squared represents the probability density of an electron. That tells us where the electron is most likely to be found in the space around the nucleus. If you want ...
by Megan Sparrow 1G
Mon Nov 02, 2020 2:52 pm
Forum: Resonance Structures
Topic: Textbook Question 2B.15
Replies: 2
Views: 18

Re: Textbook Question 2B.15

I believe you can position the resonance structure in both ways. You can have the oxygen atoms on opposite sides, or as it was shown in the textbook. When I was looking online, I found this photo below. Either way is a correct representation of the resonance structure. In addition, during Dr. Lavell...
by Megan Sparrow 1G
Mon Nov 02, 2020 2:43 pm
Forum: SI Units, Unit Conversions
Topic: Using a Calculator
Replies: 10
Views: 60

Re: Using a Calculator

Another good tip for scientific calculators is to set it SCI mode. Usually, the default is on FLO, but SCI shows results in scientific notation which saves time from homework and test questions. I believe our week 0 sapling optional homework noted this.
by Megan Sparrow 1G
Mon Oct 26, 2020 1:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Radial vs Angular Nodes
Replies: 2
Views: 26

Re: Radial vs Angular Nodes

Nodes in general are locations where electrons are not present. Therefore, angular nodes are either x, y, and z planes where electrons aren't present while radial nodes are sections of these axes that are closed off to electrons. This website helped explain more of this concept to me. https://chemis...
by Megan Sparrow 1G
Mon Oct 26, 2020 1:01 pm
Forum: Empirical & Molecular Formulas
Topic: Knowing chemical compounds for midterm
Replies: 2
Views: 23

Re: Knowing chemical compounds for midterm

Since we haven't reviewed the specifics in a class of the information you noted, I believe he will give us the information. I would double-check the learning outcome sheet (https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/Chem14A_Outline2_The_Quantum_World.pdf) and the equations/con...
by Megan Sparrow 1G
Mon Oct 26, 2020 12:00 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic spectroscopy vs molecular spectroscopy
Replies: 2
Views: 22

Re: Atomic spectroscopy vs molecular spectroscopy

I believe they are very similar in terms of each element and each molecule has its own individual "fingerprint". However, there may be differences in terms of energy from the light being used to promote an electron from a bonding or non-bonding orbital into one of the empty anti-bonding or...
by Megan Sparrow 1G
Mon Oct 26, 2020 11:56 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital vs. Subshell
Replies: 13
Views: 67

Re: Orbital vs. Subshell

The main difference between shell subshell and orbital is that shells are made up of electrons that share the same principal quantum number. Subshells are composed of electrons that share the same angular momentum quantum number (l), whereas orbitals are made up of electrons that are in the same ene...
by Megan Sparrow 1G
Mon Oct 26, 2020 11:24 am
Forum: Limiting Reactant Calculations
Topic: What counts as theoretical yield?
Replies: 8
Views: 59

Re: What counts as theoretical yield?

To help clarify the second part, the theoretical yield is the maximum amount of product calculated that could be produced if the reaction is precise given the limiting reagent. The reason you couldn't always add the product grams from both reactants is that you could be factoring in an excess reacta...
by Megan Sparrow 1G
Mon Oct 19, 2020 6:05 pm
Forum: Photoelectric Effect
Topic: Sapling Wk 2 Homework #7
Replies: 2
Views: 37

Re: Sapling Wk 2 Homework #7

Start by multiplying the grams of ice by the enthalpy of fusion in order to get the total energy required (in J) to melt the ice. Then substitute the given wavelength into the equation "E=(hc)/lambda" in order to find the energy per photon. Remember to convert nanometers to meters when usi...
by Megan Sparrow 1G
Mon Oct 19, 2020 5:57 pm
Forum: DeBroglie Equation
Topic: De Broglie Equation Assumption
Replies: 3
Views: 38

Re: De Broglie Equation Assumption

I'm assuming you are referring to the information that Dr. Lavelle mentioned in his last slide when going over the controversy of the equation. De Broglie hypothesized that 1) this equation works for ANY particle with momentum (which includes photons that have momentum) and 2) that it exhibits wave-...
by Megan Sparrow 1G
Mon Oct 19, 2020 10:50 am
Forum: DeBroglie Equation
Topic: Textbook Problem B.15
Replies: 4
Views: 40

Textbook Problem B.15

I was having an issue solving the parts b and c of the textbook problem B.15. The original question is: 1B.15 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 ...
by Megan Sparrow 1G
Mon Oct 19, 2020 10:40 am
Forum: Photoelectric Effect
Topic: Units of the Work Function
Replies: 7
Views: 44

Re: Units of the Work Function

I believe it is just per electron. The official definition of the work function is "the minimum quantity of energy which is required to remove an electron to infinity from the surface of a given solid, usually a metal." In addition, when solving problems where you have to find the total am...
by Megan Sparrow 1G
Mon Oct 19, 2020 10:04 am
Forum: Properties of Light
Topic: Textbook Questions
Replies: 3
Views: 50

Re: Textbook Questions

I have only completed textbook questions from parts A and B (since that is what we have gone over in class so far). It depends on what you need to work/improve on, but I found A7, A9, and A15 helpful. They were most similar to what we did in class and the Sapling Homework Assignments. For the next c...
by Megan Sparrow 1G
Mon Oct 19, 2020 9:58 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 1A.15 Empirical Equation
Replies: 7
Views: 44

Re: 1A.15 Empirical Equation

Hey! I used the empirical formula as well until I got used to the Rydberg equation. It is always helpful to know what type of Electromagnetic Radiation is created based on the electron energy emitted. Any energy level jump that ends at n=1 represents the UV series, any energy level jump to n=2 is th...
by Megan Sparrow 1G
Mon Oct 12, 2020 12:06 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Measuring Masses in Experiments
Replies: 2
Views: 39

Re: Measuring Masses in Experiments

I'm actually not too sure about this, but maybe it has to do with the fact that you can never really be 100% precise. For example, there will likely be impurities, human error, and other issues when making solutions. Just an idea but someone else might have a confirmed answer.
by Megan Sparrow 1G
Mon Oct 12, 2020 11:55 am
Forum: Photoelectric Effect
Topic: How does the photoelectric experiment explain the particle theory of light? [ENDORSED]
Replies: 3
Views: 81

Re: How does the photoelectric experiment explain the particle theory of light? [ENDORSED]

A brief summary that shows why the photoelectric experiment can be explained by particle theory is because it follows the conservation of energy model. This is crucial to particle theory and is shown in the photoelectric experiment. Since increasing light intensity didn't eject electrons, the system...
by Megan Sparrow 1G
Mon Oct 12, 2020 11:48 am
Forum: *Black Body Radiation
Topic: Resources to Learn More About Black Body Radiation
Replies: 2
Views: 27

Re: Resources to Learn More About Black Body Radiation

I was interested as well! Thank you for posting these. Here is another link I found from UCSD summarizing the Black Body Radiation:
https://quantummechanics.ucsd.edu/ph130 ... ode48.html
by Megan Sparrow 1G
Mon Oct 12, 2020 11:45 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: How to know whether answer is in mols or atoms
Replies: 5
Views: 71

Re: How to know whether answer is in mols or atoms

I was having the same issue. I believe that questions were asking for the number of molecules in terms of moles (a measurement of the atoms or molecules in a give data set). I believe the tests will be clearer on the wording. Also, I'm not sure if this helps but usually when trying to find exact amo...
by Megan Sparrow 1G
Mon Oct 12, 2020 11:42 am
Forum: Properties of Light
Topic: c=λv
Replies: 5
Views: 78

Re: c=λv

Sorry, the link I sent earlier isn't working. If you search "5.2: Wavelength and Frequency Calculations," the website I am referring to should be the first post.
by Megan Sparrow 1G
Mon Oct 12, 2020 11:39 am
Forum: Properties of Light
Topic: c=λv
Replies: 5
Views: 78

Re: c=λv

Hey, I believe Nika was correct in the reply earlier, but here's a link that helps clarify part of the question you asked.

https://chem.libretexts.org/Bookshelves ... try_(CK-12)/05%3A_Electrons_in_Atoms/5.02%3A_Wavelength_and_Frequency_Calculations
by Megan Sparrow 1G
Wed Oct 07, 2020 10:12 am
Forum: Student Social/Study Group
Topic: Discussion Group 1G GroupMe Link
Replies: 1
Views: 20

Discussion Group 1G GroupMe Link

Hey! For anyone who already isn't in the Discussion Group 1G GroupMe, the link is below.

https://groupme.com/join_group/63031900/Abx5QCiQ
by Megan Sparrow 1G
Wed Oct 07, 2020 10:03 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 221
Views: 116163

Re: Advice from a Medical Student [ENDORSED]

This may be too late to receive a response, but how do you recommend preparing for medical school during the pandemic? Most internships and volunteer opportunities have been shut down temporarily, so do you know of any online resources or useful things to help prepare that involve social distancing?
by Megan Sparrow 1G
Wed Oct 07, 2020 9:58 am
Forum: Administrative Questions and Class Announcements
Topic: Sapling Homework Submission Confirmation [ENDORSED]
Replies: 2
Views: 48

Sapling Homework Submission Confirmation [ENDORSED]

Hello! I have completed the assigned Sapling homework for this week, but I'm not sure how to confirm it is done or if there is an extra step I need to do. When I click on the assignment, it said "Assignment score: 100%," but there is no other confirmation that it is complete (ex. doesn't s...
by Megan Sparrow 1G
Wed Oct 07, 2020 9:47 am
Forum: Molarity, Solutions, Dilutions
Topic: theoretical and actual yeild
Replies: 4
Views: 49

Re: theoretical and actual yeild

Sorry, I forgot to mention, you will know the ratio based on the balanced equation. Sometimes it might be tricky though because they can appear unbalanced at first, and you will have to balance or even create it yourself based on knowledge given.
by Megan Sparrow 1G
Wed Oct 07, 2020 9:45 am
Forum: Molarity, Solutions, Dilutions
Topic: theoretical and actual yeild
Replies: 4
Views: 49

Re: theoretical and actual yeild

Keep in mind that the limiting reagent is the reactant that is completely used up or consumed when the reaction is complete. I believe in the example you are referring to, the original reaction can be modeled by this balanced equation: 1CaC2 (s) + 2H2O (l) -> Ca(OH)2 (aq) + C2H2 (g). The 1:2 ratio r...
by Megan Sparrow 1G
Wed Oct 07, 2020 9:31 am
Forum: SI Units, Unit Conversions
Topic: Textbook
Replies: 22
Views: 164

Re: Textbook

Hey! I'm not sure if you ordered the textbook/codes to your house or to one of the UCLA stores (if you are on campus/in an apartment), but I ordered my book to be shipped to a UCLA store. The website is very slow in terms of updating processing times, so I recommend emailing "textonline@asucla....

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