Search found 89 matches

by Qiu Ya Wu 4I
Thu Feb 20, 2020 2:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cathode to the Right Rule
Replies: 6
Views: 17

Re: Cathode to the Right Rule

A word of caution: an UA told me that the book is really inconsistent with the visual diagram conventions so I would always double check!
by Qiu Ya Wu 4I
Thu Feb 20, 2020 2:20 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing/reducing agent
Replies: 3
Views: 10

Oxidizing/reducing agent

Can someone please explain to me what an oxidizing/reducing agent is? From the homework problems, it seems as if the compound losing electrons is the reducing agent and the compound gaining electrons is the oxidizing agent but that sounds incorrect to me.
by Qiu Ya Wu 4I
Wed Feb 19, 2020 11:39 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Material
Replies: 3
Views: 9

Re: Test 2 Material

I believe Lavelle has said that he will be finished lecturing for Test 2 material after Monday next week.
by Qiu Ya Wu 4I
Wed Feb 19, 2020 11:38 pm
Forum: Administrative Questions and Class Announcements
Topic: HW7
Replies: 14
Views: 26

Re: HW7

Essentially all problems in the textbook up to what Lavelle has covered so far can be fair game!
by Qiu Ya Wu 4I
Wed Feb 19, 2020 11:37 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number of Ozone
Replies: 6
Views: 22

Oxidation number of Ozone

Is the overall oxidation number for ozone 0? How could this occur if the oxygen atom is commonly regarded to have an oxidation number of -2?
by Qiu Ya Wu 4I
Thu Feb 13, 2020 8:10 pm
Forum: Administrative Questions and Class Announcements
Topic: grading curve
Replies: 10
Views: 61

Re: grading curve

Seeing as the class average was about a B+ for CHEM 14A, I would not expect a sizeable curve.
by Qiu Ya Wu 4I
Thu Feb 13, 2020 8:09 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm grading
Replies: 8
Views: 70

Re: Midterm grading

Jessica Esparza 2H wrote:It is uniform graders. Does anyone know if it'll take about a week like last time?


Yes they should be handing back the midterm at the end of lectures about a week from now!
by Qiu Ya Wu 4I
Thu Feb 13, 2020 8:08 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 1
Views: 19

Re: Test 2

The second test will likely cover the end of outline 4 and outline 5!
by Qiu Ya Wu 4I
Thu Feb 13, 2020 8:07 pm
Forum: Calculating Work of Expansion
Topic: Last Question on the Midterm [ENDORSED]
Replies: 5
Views: 66

Re: Last Question on the Midterm [ENDORSED]

I'm not sure about the exact details of the question, but the answers for the midterms should be posted soon on Lavelle's website complete with step by step solutions and a point breakdown!
by Qiu Ya Wu 4I
Thu Feb 06, 2020 1:58 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: 4H.9
Replies: 1
Views: 13

4H.9

Container A is filled with 1.0 mol of the atoms of an ideal monatomic gas. Container B has 1.0 mol of atoms bound together as diatomic molecules that are not vibrationally active. Container C has 1.0 mol of atoms bound together as diatomic molecules that are vibrationally active. The containers all ...
by Qiu Ya Wu 4I
Mon Feb 03, 2020 10:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Lyndon Bui Workshops
Replies: 7
Views: 102

Re: Lyndon Bui Workshops

He has not posted it yet! But I would definitely be on the lookout as he should be uploading it soon.
by Qiu Ya Wu 4I
Mon Feb 03, 2020 5:19 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Thermodynamics Laws
Replies: 4
Views: 27

Re: Thermodynamics Laws

The first law of thermodynamics is the change in internal energy = heat + work and the second law is delta S = q/T.
by Qiu Ya Wu 4I
Mon Feb 03, 2020 5:17 pm
Forum: Phase Changes & Related Calculations
Topic: phase changes, temperature constant?
Replies: 11
Views: 36

Re: phase changes, temperature constant?

In addition, you can think of the temperature remaining the same due to all the added heat being used to break the bonds between molecules of a substance.
by Qiu Ya Wu 4I
Mon Feb 03, 2020 5:15 pm
Forum: Phase Changes & Related Calculations
Topic: intensive/extensive
Replies: 4
Views: 16

Re: intensive/extensive

I think it would be good to remember that entropy is an extensive property!
by Qiu Ya Wu 4I
Mon Feb 03, 2020 5:14 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Midterm Review
Replies: 7
Views: 67

Re: Midterm Review

He typically posts a worksheet on chemistry community! He'll probably let us know what to type in the search bar to find it in the following days.
by Qiu Ya Wu 4I
Thu Jan 30, 2020 9:51 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Material
Replies: 13
Views: 64

Re: Midterm Material

An UA told me that we were going to cover material up to Outline 4. There are usually a bunch of review sessions that are held by BOTH lavelle and the UA's so definitely be on the lookout for those!
by Qiu Ya Wu 4I
Thu Jan 30, 2020 9:50 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Enthalpy at Constant Pressure
Replies: 2
Views: 14

Re: Enthalpy at Constant Pressure

Enthalpy at constant pressure is referring to essentially an open system with an air pressure of 1.0 atm. With an open system, the gas has the ability to push the air on top of the beaker out of the way, therefore performing work onto it.
by Qiu Ya Wu 4I
Mon Jan 27, 2020 7:53 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 11
Views: 38

Re: Hess's Law

In order to use Hess's Law to solve for the change in enthalpy, you will have to know the changes in enthalpy for intermediate reactions that occur with the reactants given to form the end product.
by Qiu Ya Wu 4I
Mon Jan 27, 2020 7:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Last Lecture Week 3 Lec 3
Replies: 1
Views: 13

Re: Last Lecture Week 3 Lec 3

Are you referring to the example dealing with the combustion of methane? If so, I don't believe that we needed to calculate the mass, but rather the change in enthalpy by adding up the sum of the standard enthalpies of formation for the products and subtracting the sum from the standard enthalpies o...
by Qiu Ya Wu 4I
Mon Jan 27, 2020 7:45 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: q and deltaH
Replies: 3
Views: 12

Re: q and deltaH

During the lecture, Lavelle instructed us that q(p)=delta H!
by Qiu Ya Wu 4I
Mon Jan 20, 2020 5:05 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 6B 9
Replies: 1
Views: 10

Re: 6B 9

Yes I had that issue too! I believe it's an error on the solution manual.
by Qiu Ya Wu 4I
Mon Jan 20, 2020 5:04 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Directionality of Acid/Base Equations
Replies: 4
Views: 17

Re: Directionality of Acid/Base Equations

For the purposes of this course, acid/base reactions are reversible only with weak acids or bases.
by Qiu Ya Wu 4I
Mon Jan 20, 2020 5:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH Examples
Replies: 3
Views: 30

Re: pH Examples

I think it would be a good idea for you to memorize the chemical formula just in case! It's relatively straight forward.
by Qiu Ya Wu 4I
Mon Jan 20, 2020 5:00 pm
Forum: Ideal Gases
Topic: Acid and Bases
Replies: 16
Views: 45

Re: Acid and Bases

pH measures the amount of H3O+ ions produced due to the reaction. The more H30+ ions a reaction can produce, the more acidic it is. It might also be helpful to remember that pH and the concentration of H3O+ ions are inversely related.
by Qiu Ya Wu 4I
Mon Jan 20, 2020 4:57 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: "Quick Way" for predicting response to changes in volume/pressure
Replies: 3
Views: 18

Re: "Quick Way" for predicting response to changes in volume/pressure

To add on, this system works this way due to Le Chatelier's principle since favoring the side of the reaction with less moles of gas when pressure is applied means that there will be less molecules ultimately bouncing off the walls of the container and creating additional pressure.
by Qiu Ya Wu 4I
Mon Jan 13, 2020 6:58 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier
Replies: 3
Views: 19

Re: Le Chatelier

Increasing the total pressure of the system will cause equilibrium to shift to the side with fewer moles Changing the pressure of a system will not change the equilibrium constant k itself, but it will cause a net increase in the equilibrium concentration of the side of a reaction with less moles d...
by Qiu Ya Wu 4I
Mon Jan 13, 2020 6:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 8
Views: 39

Re: Kc and Kp

but can't you also use Kc for gases? so the phases don't really tell you anything but just go off of what you're given? You can also use Kc for gases since a lot of the reactions we deal with have heterogeneous equilibria. If the units for the amount of gas are in L/mol, use concentration and if th...
by Qiu Ya Wu 4I
Mon Jan 13, 2020 6:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 8
Views: 39

Re: Kc and Kp

Solids and liquids aren't included in the equilibrium constant because there's no such thing as the "concentration" of a solid and liquids (solvents) can usually be expected to have nearly the same concentration on both sides of the equation so they would cancel out to 1 anyways if we divi...
by Qiu Ya Wu 4I
Mon Jan 13, 2020 6:48 pm
Forum: Ideal Gases
Topic: R constant
Replies: 6
Views: 25

Re: R constant

Lavelle gives you 4 different values for the R constant on his formula sheet during tests. Whichever one you use depends on the units given in the problem.
by Qiu Ya Wu 4I
Mon Jan 13, 2020 6:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Are Lectures Bruincasted?
Replies: 10
Views: 60

Re: Are Lectures Bruincasted?

None of Lavelle's lectures are recorded during the quarter with the exception of his lecture series on early chemical equilibria posted on his website.
by Qiu Ya Wu 4I
Mon Jan 13, 2020 6:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ATP Hydrolysis
Replies: 2
Views: 9

Re: ATP Hydrolysis

I don't believe that Lavelle has gone over that topic in lecture yet but seeing as it's listed on the outline and not mentioned in the books, I'd advise you to make a habit of attending his lectures as oftentimes he likes to emphasize specific concepts about biological examples such as this that may...
by Qiu Ya Wu 4I
Wed Jan 08, 2020 9:16 pm
Forum: Ideal Gases
Topic: PV=nRT equation manipulation
Replies: 13
Views: 81

Re: PV=nRT equation manipulation

We move elements of the equation around to solve for P and the concentration so we can convert the partial pressure of a gas to its concentration. Being able to do so will be helpful when we deal with heterogenous equilibria.
by Qiu Ya Wu 4I
Wed Jan 08, 2020 9:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.35
Replies: 4
Views: 27

5.35

The following plot shows how the partial pressures of reactant and products vary with time for the decomposition of compound A into compounds B and C. All three compounds are gases. Use this plot to do the following: (a) Write a balanced chemical equation for the reaction. (b) Calculate the equilibr...
by Qiu Ya Wu 4I
Wed Jan 08, 2020 9:04 pm
Forum: Ideal Gases
Topic: Units for Pressure
Replies: 6
Views: 44

Re: Units for Pressure

In one of Lavelle's video lectures he asserted that we will treat 1 bar as equal to 1 atmosphere for the purposes of this course.
by Qiu Ya Wu 4I
Wed Jan 08, 2020 9:02 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling Learning
Replies: 9
Views: 48

Re: Sapling Learning

Sapling learning assignments did not account for any portion of our grade last quarter for 14A!
by Qiu Ya Wu 4I
Wed Jan 08, 2020 10:39 am
Forum: Ideal Gases
Topic: Equilibrium
Replies: 7
Views: 31

Re: Equilibrium

Q is known as the reaction quotient and K is known as the equilibrium constant. One important thing to note is that K stays constant for a specific reaction at a specific temperature while Q does not have a predetermined value.
by Qiu Ya Wu 4I
Tue Dec 03, 2019 5:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Plane
Replies: 2
Views: 16

Re: Plane

Generally, only molecules arranged in planar arrangements, such as linear, trigonal planar, square planar, and perhaps t-shaped (please correct me if I am incorrect) contained atoms that are considered to be on one plane.
by Qiu Ya Wu 4I
Tue Dec 03, 2019 5:46 pm
Forum: Lewis Acids & Bases
Topic: Cations and Anions
Replies: 3
Views: 24

Re: Cations and Anions

Additionally, there are instances of acidic anions (when the reactant is polyprotic). The book goes into this in detail and there’s a chart of that lists the few times this occurs.
by Qiu Ya Wu 4I
Tue Dec 03, 2019 5:39 pm
Forum: Administrative Questions and Class Announcements
Topic: Early Quantum Review Session
Replies: 3
Views: 43

Re: Early Quantum Review Session

I left 30 minutes in but keep us updated on whether or not he shows!
by Qiu Ya Wu 4I
Tue Dec 03, 2019 4:44 pm
Forum: Identifying Acidic & Basic Salts
Topic: HW 6D11
Replies: 7
Views: 90

Re: HW 6D11

I just stumbled upon this section in my lecture notes and to add on to what everyone has been saying, Lavelle clarified that the hydrated metal cation will release H+ ions to form hydronium ions with water until the overall charge of the ion becomes neutral. When this happens, any anions attached to...
by Qiu Ya Wu 4I
Mon Dec 02, 2019 10:00 pm
Forum: Identifying Acidic & Basic Salts
Topic: HW 6D11
Replies: 7
Views: 90

Re: HW 6D11

"When copper(II) nitrate dissociates in water, it forms Cu2+ and NO3-. Cu2+ is acidic since it is a transition metal, and NO3- is neutral because its the base of a strong acid, so it's relatively weak and doesn't do anything (spectator ion)." Lavelle gave this answer when answering another...
by Qiu Ya Wu 4I
Mon Dec 02, 2019 8:24 pm
Forum: Bronsted Acids & Bases
Topic: Fundamentals J.13c
Replies: 2
Views: 21

Fundamentals J.13c

2HI(aq) + CaO(s) --> CaI2(aq) + H2O(l)

Can someone explain the chemical reaction that is going on here and why CaO is a base? I understand why HI functions as an acid since it can pretty easily give off the H+ ion, but I'm not sure how these reactants form those products.
by Qiu Ya Wu 4I
Mon Nov 25, 2019 1:40 pm
Forum: Bronsted Acids & Bases
Topic: Ions and Bronsted Acids and Bases
Replies: 1
Views: 17

Re: Ions and Bronsted Acids and Bases

I think it would be helpful to memorize the charges for the common polyatomic ions since it's not guaranteed that Lavelle would provide them on the final; it could save you a lot of time with the oxidation number calculations for coordination compunds if these ions show up as ligands as well.
by Qiu Ya Wu 4I
Mon Nov 25, 2019 1:36 pm
Forum: Bronsted Acids & Bases
Topic: Why do acids and bases react?
Replies: 3
Views: 25

Re: Why do acids and bases react?

Assuming that HBr + K+(OH)- --> KBr + H2O is your intended reaction, this reaction is an example of a neutralization reaction, which you could read more about in Fundamentals J.3. The H+ ion dissociates with the Br in the presence of a metal hydroxide (KOH-) since HBr is a strong acid and KOH- is a ...
by Qiu Ya Wu 4I
Mon Nov 25, 2019 1:29 pm
Forum: Bronsted Acids & Bases
Topic: Difference between Bronsted Acids and Bases
Replies: 1
Views: 21

Re: Difference between Bronsted Acids and Bases

Bronsted acids are defined as proton donors while Bronsted bases are defined as proton acceptors. In this case, the NH3 is a Bronsted base since a H+ ion (really just a proton) could bond to the N as it has an extra unoccupied bonding site. I'm not sure if you could make the generalization that mole...
by Qiu Ya Wu 4I
Mon Nov 25, 2019 1:08 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Displacement of Water Molecules in Aqueous Solution
Replies: 1
Views: 27

Displacement of Water Molecules in Aqueous Solution

Can someone explain to me how molecules such as NH3 displace the water molecules bonded to a metal ion in an aqueous solution during a chemical reaction?
by Qiu Ya Wu 4I
Mon Nov 25, 2019 12:58 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: edta
Replies: 1
Views: 21

edta

Would the edta ligand form an octahedral complex when it bonds with a metal ion since it is hexadentate and has the coordination number 6? If so, would the entire ligand have to wrap around the metal ion? Additionally, why are the points of attachment for the edta ligand only on the N atoms and the ...
by Qiu Ya Wu 4I
Fri Nov 22, 2019 9:53 pm
Forum: Bond Lengths & Energies
Topic: Dissociation Bond Length
Replies: 3
Views: 56

Re: Dissociation Bond Length

I think the exact bond length and dissociation energy for a molecule is something that has to be experimentally determined. He might ask you to compare the bond lengths of certain molecules, but general rules concering atomic radii should be able to help you compare their lengths qualitatively.
by Qiu Ya Wu 4I
Wed Nov 20, 2019 6:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Bond angles in Trigonal Bipyramidal
Replies: 4
Views: 27

Bond angles in Trigonal Bipyramidal

Does a trigonal bypryramidal shape have bond angles of 90, 120, AND 180? I have 180 degrees written down in my notes as well but the book seems to exclude it and only states the angles of 90 and 120.
by Qiu Ya Wu 4I
Tue Nov 19, 2019 7:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Cylindrical Symmetry
Replies: 1
Views: 21

Cylindrical Symmetry

What exactly does "cylindrical symmetry around the internuclear axis" mean? I understand that it has something to do with allowing the molecule to rotate while still maintaining an overlap of the bonding orbitals, but I'm having a difficult time visualizing "cylindrical symmetry".
by Qiu Ya Wu 4I
Tue Nov 19, 2019 7:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Effect of lone pair on bond angles
Replies: 2
Views: 29

Effect of lone pair on bond angles

Is there any way to reason why the bond angle between NH3 is larger than the bond angle of SO3(2-)? I believe Lavelle sort of touched on why it makes sense for one to have a bond angle of 107 degrees and the other to have one of 106 degrees but I didn't manage to catch his explanation.
by Qiu Ya Wu 4I
Wed Nov 13, 2019 8:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 15
Views: 154

Re: Test 2

Ghadir Seder 4F wrote:Whats the first topic that lavelle lectured about after our midterm?


I believe the first lecture after the midterm on last Friday went in further detail in regards to principles of chemical bonding, more specifically induced dipole-induced dipole bonding and hydrogen bonding.
by Qiu Ya Wu 4I
Wed Nov 13, 2019 8:12 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorizing and Recognizing Molecular Shapes
Replies: 4
Views: 26

Re: Memorizing and Recognizing Molecular Shapes

I think that we are expected to recognize the shapes of simple molecules up to octahedral, as Lavelle didn't go over pentagonal bipyramidal in class. I wouldn't be surprised if a question on the bond angle between a specific trio of atoms came up on the test, so memorizing those would also be helpful.
by Qiu Ya Wu 4I
Wed Nov 13, 2019 8:09 pm
Forum: Dipole Moments
Topic: Do lone pairs repel more?
Replies: 5
Views: 35

Re: Do lone pairs repel more?

Yes! Lone pairs also have a stronger degree of repulsion since there's only one positive force that counteracts the energy of a lone pair, namely the nucleus of the atom to which the lone pair belongs to while bonded pairs have 2 positive nuclei in between them which act as 2 positive forces that co...
by Qiu Ya Wu 4I
Wed Nov 13, 2019 8:06 pm
Forum: Bond Lengths & Energies
Topic: Interaction Potential Energy equation
Replies: 7
Views: 46

Re: Interaction Potential Energy equation

I think this equation was referenced by Lavelle to emphasize the importance of the distance between two bonded atoms and their charges in determining the strength of a bond and whether the resulting compound is a solid, liquid, or gas. I think the more generalized equation, the one listed on the las...
by Qiu Ya Wu 4I
Mon Nov 11, 2019 2:36 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: Test 2
Replies: 6
Views: 39

Re: Test 2

I believe Test 2 will test on the topics posted on Outline 4 and will include topics like induced dipole-induced dipole bonding that were omitted from the midterm and on Chapters 2E-2F, which Lavelle should be able to cover within the next three lectures.
by Qiu Ya Wu 4I
Tue Nov 05, 2019 7:23 pm
Forum: Octet Exceptions
Topic: Naming molecules
Replies: 2
Views: 33

Re: Naming molecules

I don't think Lavelle expects us to know how which molecular formula corresponds to which molecular name but I think starting to look at a list of common polyatomic ions (there's only around 10-20 of them) and studying prefixes and suffixes would be a good place to start studying.
by Qiu Ya Wu 4I
Tue Nov 05, 2019 7:21 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Oxidation state for Midterm
Replies: 1
Views: 25

Re: Oxidation state for Midterm

I don't believe it is part of Lavelle's outline but I would recommend studying it as it's not a hard concept to grasp and can help you immensely in drawing lewis structures.
by Qiu Ya Wu 4I
Tue Nov 05, 2019 7:18 pm
Forum: Properties of Light
Topic: Good Luck On Midterm
Replies: 1
Views: 56

Re: Good Luck On Midterm

Thanks for the support! Good luck to you as well tomorrow :) I would also recommend double checking the location of your midterm since everyone gets split up.
by Qiu Ya Wu 4I
Tue Nov 05, 2019 7:15 pm
Forum: Bond Lengths & Energies
Topic: de Broglie threshold
Replies: 4
Views: 59

Re: de Broglie threshold

Wavelike properties fail to be detected past 10^-15m. For reference, an electron has a wavelength of 10^-12 m and an Angstrom is 10^-10m.
by Qiu Ya Wu 4I
Tue Nov 05, 2019 2:50 pm
Forum: Photoelectric Effect
Topic: Why does the photoelectric effect not eject light?
Replies: 1
Views: 44

Why does the photoelectric effect not eject light?

Through my studies for the midterm, I came across the detail that passing an electric current through hydrogen gas causes electromagnetic radiation of a certain frequency to be emitted as an electron goes from a higher to a lower energy level. Given this, why does an electron, and not electromagneti...
by Qiu Ya Wu 4I
Thu Oct 31, 2019 8:11 pm
Forum: Trends in The Periodic Table
Topic: Electronegativity Trend
Replies: 2
Views: 14

Re: Electronegativity Trend

Electronegativity follows the same general trend as ionization energy, increasing as you go up and to the right!
by Qiu Ya Wu 4I
Thu Oct 31, 2019 8:08 pm
Forum: Electronegativity
Topic: 2D.1
Replies: 4
Views: 41

Re: 2D.1

I believe you have mistakenly replaced indium with tellerium in your final answer. The correct answer is In<Sn<Sb<Se, which you should have arrived at based on your thought process if you didn't switch up the two elements
by Qiu Ya Wu 4I
Thu Oct 31, 2019 8:04 pm
Forum: Lewis Structures
Topic: Angstrom Measurements on Lewis Structures
Replies: 3
Views: 19

Re: Angstrom Measurements on Lewis Structures

Angstrom is a non-SI unit that is preferred in calculating bond lengths; one angstrom is equivalent to 10^-10 m. I believe it would be wise for you to memorize the conversion between angstrom and meters as this is an unit that will probably show up repeatedly in future chemistry courses.
by Qiu Ya Wu 4I
Thu Oct 31, 2019 8:01 pm
Forum: Photoelectric Effect
Topic: Ionization Energy vs Threshold Energy
Replies: 4
Views: 34

Re: Ionization Energy vs Threshold Energy

Threshold energy and ionization energy both have to do with the minimum energy required to remove an electron from an element but threshold energy refers to the energy needed to remove an electron from a metal (photoelectric effect) while ionization energy has to do with the energy needed to remove ...
by Qiu Ya Wu 4I
Tue Oct 29, 2019 5:27 pm
Forum: Trends in The Periodic Table
Topic: Energy of Noble Gases
Replies: 2
Views: 14

Re: Energy of Noble Gases

Noble gases are the least reactive and most stable out of all the elements in their period, but I'm uncertain as to whether this puts them at a lower energy level since their valence electrons are still filling the p subshells, which are higher in energy than the s subshells. Fulfilling hunds rule c...
by Qiu Ya Wu 4I
Wed Oct 23, 2019 4:42 pm
Forum: Ionic & Covalent Bonds
Topic: What topic are we on?
Replies: 11
Views: 107

Re: What topic are we on?

I think this week was more focused on building upon prior concepts in the Quantum World unit as we have barely delved into the new unit so I would do my homework on the questions in Outline 2! However, if you'd like to move ahead I'm sure the questions on Outline 3 are fair game as well.
by Qiu Ya Wu 4I
Wed Oct 23, 2019 4:40 pm
Forum: Resonance Structures
Topic: Bond types
Replies: 2
Views: 25

Re: Bond types

A triple bond is most stable since the bonds have shorter lengths, thereby holding the electrons more tightly together.
by Qiu Ya Wu 4I
Wed Oct 23, 2019 4:36 pm
Forum: Lewis Structures
Topic: Exceptions
Replies: 3
Views: 24

Re: Exceptions

I believe that it would just be far more reasonable for these atoms to gain/lose electrons to fulfill the 1s shell rather than gaining all those excess electrons to fill the entire 2nd shell.
by Qiu Ya Wu 4I
Wed Oct 23, 2019 4:31 pm
Forum: Ionic & Covalent Bonds
Topic: Lewis Structures
Replies: 3
Views: 41

Re: Lewis Structures

The element with the lowest ionization energy is the central atom since it takes the least amount of energy for an electron to detach from the atom. This means that it can more readily form bond(s) with other atoms.
by Qiu Ya Wu 4I
Wed Oct 23, 2019 4:27 pm
Forum: Lewis Structures
Topic: Valence e in d block
Replies: 5
Views: 40

Re: Valence e in d block

Writing out the d block elements' electric configurations would help you immensely in counting their valence electrons! Just remember to only count electrons in the outermost shell. The electron configuration of Zinc is formally [Ar] 3d¹⁰4s², but you should only focus on the electrons in the outermo...
by Qiu Ya Wu 4I
Tue Oct 22, 2019 4:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of Tantalum
Replies: 1
Views: 29

Electron Configuration of Tantalum

I didn't realize that the homework problems list specifically told us to skip this problem (1E.21 c) so I went ahead and tried to figure out the electron configuration of tantalum and arrived at Xe 4f7 5d10 6s2, which is far from the correct answer. I'm curious as to whether there's a fundamental pr...
by Qiu Ya Wu 4I
Wed Oct 16, 2019 4:43 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron spin
Replies: 8
Views: 79

Re: Electron spin

Since there are two possible electrons that can have the same n,l, and m quantum numbers, we use +1/2 and -1/2 spin to distinguish them. For that reason, there can only be 2 spin states.
by Qiu Ya Wu 4I
Wed Oct 16, 2019 4:32 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Difference Between Ground and Excited States
Replies: 3
Views: 22

Re: Difference Between Ground and Excited States

The ground state can also be described as the lowest possible energy level that the atom can occupy and can be represented in a hydrogen atom when n=1 as -hR.
by Qiu Ya Wu 4I
Wed Oct 16, 2019 4:27 pm
Forum: *Shrodinger Equation
Topic: Equations for Quantum Topics
Replies: 3
Views: 24

Re: Equations for Quantum Topics

I think those 3 equations basically cover the fundamentals of quantum mechanics, but there are several other equations that form the intermediate steps of those equations such as c=λv, E=hv, E=pc, p=mv, E(n)=-hR/N^2, λ=h/p, and E(k)=1/2mv^2 that would be helpful to keep in mind.
by Qiu Ya Wu 4I
Wed Oct 16, 2019 4:19 pm
Forum: Quantum Numbers and The H-Atom
Topic: X Y and Z
Replies: 7
Views: 75

Re: X Y and Z

In his lecture today, Lavelle emphasized that the plane the electron is found in is arbitrary and different textbooks associate different l values with different x,y, and z planes.
by Qiu Ya Wu 4I
Wed Oct 16, 2019 4:14 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Energy levels
Replies: 3
Views: 28

Re: Energy levels

I believe the 4d orbital has a higher energy level than the 5s orbital, but not the 5p orbital. The graph I linked below might be helpful. https://webs.anokaramsey.edu/chemistry/ ... iagram.PDF
by Qiu Ya Wu 4I
Thu Oct 10, 2019 12:57 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test Equation Sheet
Replies: 8
Views: 67

Re: Test Equation Sheet

My TA actually handed out a copy of equations that Lavelle provides on the test sheet. For Test 1, the only relevant formula is that of Avogadro's constant. I imagine it will be much more helpful for tests later in the year as it includes a lot of fundamental constants and equations from the quantum...
by Qiu Ya Wu 4I
Wed Oct 09, 2019 9:30 pm
Forum: SI Units, Unit Conversions
Topic: Practice Problems?
Replies: 11
Views: 172

Re: Practice Problems?

My TA specifically referred us to review H7, L35, M9, and M15 during our discussion as they were considered the more complicated problems of the bunch. I would look over them before the test just in case!
by Qiu Ya Wu 4I
Wed Oct 09, 2019 9:24 pm
Forum: SI Units, Unit Conversions
Topic: Test 1
Replies: 9
Views: 142

Re: Test 1

The test covers topics beyond what was covered in the Audio-Visual focus topics! I believe a comprehensive list of concepts it will test us on are bullet pointed on Outline 1.
by Qiu Ya Wu 4I
Mon Oct 07, 2019 10:50 pm
Forum: Molarity, Solutions, Dilutions
Topic: Polyatomic ions on Test 1
Replies: 4
Views: 71

Polyatomic ions on Test 1

Does anyone know if the test will explicitly state the molecular formula for all compounds? Or are we expected to remember the structure of polyatomic ions like nitrate and ammonium?
by Qiu Ya Wu 4I
Mon Oct 07, 2019 10:42 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar Mass
Replies: 7
Views: 84

Re: Molar Mass

Perhaps you could multiply the molecule's weight by Avogadro's number to find the mass for 1 mole of that particular molecule. Doing should give you the molar mass of the molecule.
by Qiu Ya Wu 4I
Tue Oct 01, 2019 9:45 pm
Forum: Significant Figures
Topic: General Rules to Help with Sig Figs
Replies: 18
Views: 212

Re: General Rules to Help with Sig Figs

Can you explain the difference between #4 and #5? Also, would the two zeroes before 341 but after the decimal point in 0.00341be considered insignificant?
by Qiu Ya Wu 4I
Tue Oct 01, 2019 9:41 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Formula Units
Replies: 6
Views: 82

Re: Formula Units

I believe Avogadro's number can be applied to the amount of atoms, compunds, and formula units in a mole alike. To my knowledge, there has never been a scenario where the conversion between moles and formula units did not utilize Avogadro's number in some manner.
by Qiu Ya Wu 4I
Mon Sep 30, 2019 11:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 142
Views: 3681

Re: Advice from a Medical Student - Part II [ENDORSED]

Thank you so much for taking the time to offer us undergraduates guidance despite of your busy schedule as a medical school student! How do you think UCLA has helped you in your med school pursuits? Specifically, what resources should we be taking advantage of?
by Qiu Ya Wu 4I
Mon Sep 30, 2019 11:01 pm
Forum: Molarity, Solutions, Dilutions
Topic: Homework Problem G.17
Replies: 4
Views: 58

Re: Homework Problem G.17

I suggest that you view the two compounds as completely separate from one another as they have different molar masses. For part b, you can calculate the mass needed by first finding the amount of moles in CuSo4 . 5H20 and then multiplying it by its molar mass, just as you did with part a but with a ...
by Qiu Ya Wu 4I
Mon Sep 30, 2019 10:47 pm
Forum: Molarity, Solutions, Dilutions
Topic: Help on G25
Replies: 3
Views: 65

Help on G25

"Practitioners of the branch of alternative medicine known as homeopathy claim that very dilute solutions of substances can have an effect. Is the claim plausible? To explore this question, suppose that you prepare a solution of a supposedly active substance, X, with a molarity of 0.10 mol/L. T...

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