Search found 94 matches

by Jasmine 3L
Sat Dec 07, 2019 10:58 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.5 Part C
Replies: 1
Views: 8

6B.5 Part C

Can someone explain why there are 2 OH-?
by Jasmine 3L
Sat Dec 07, 2019 10:27 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.1
Replies: 2
Views: 19

6B.1

Why is there a [HCL]0 on the denominator? Isn't the new molarity just going to be 0.12 x [HCL]0 since the molar concentration is reduced to 12% of the initial value?
by Jasmine 3L
Sat Dec 07, 2019 11:22 am
Forum: Conjugate Acids & Bases
Topic: Neutralization Equations
Replies: 3
Views: 24

Neutralization Equations

Looking at question J.7, for neutralization equations in general, since they are balanced, are all of the reactants (and products) going to contain a neutral charge?
And applying this to a broader spectrum, do all chemical equations have reactants and products that have a neutral charge?
by Jasmine 3L
Sat Dec 07, 2019 3:41 am
Forum: Bronsted Acids & Bases
Topic: Homework J.7
Replies: 1
Views: 10

Homework J.7

How do you know the acid and base needed to create zinc nitrite in part C of the question: "Select an acid and a base for a neutralization reaction that results in the formation of (a) potassium bromide; (b) zinc nitrite; (c) calcium cyanide, Ca(CN)2; (d) potassium phosphate. Write the balanced...
by Jasmine 3L
Sat Dec 07, 2019 3:17 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Why do acids and bases donate/accept proton?
Replies: 1
Views: 36

Why do acids and bases donate/accept proton?

Acids and bases, is there a reason why these compounds want to accept/donate a proton? Doing so causes their molecule to be less stable so why do it? Why gain a positive or negative charge when you can remain stable at net charge = 0? This question kind of came up from me trying to understand why KO...
by Jasmine 3L
Sat Dec 07, 2019 1:24 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Identifying Acids and Bases
Replies: 2
Views: 12

Identifying Acids and Bases

Rather than memorizing strong acids and bases (and thus knowing which are weak acids and bases), is there a way to tell from the molecule's structure? Like lone pairs, charges, etc?
by Jasmine 3L
Sat Dec 07, 2019 1:21 am
Forum: Lewis Acids & Bases
Topic: List of Strong Acids and Bases
Replies: 2
Views: 16

List of Strong Acids and Bases

Does anyone know where the list of strong acids and strong bases that we need to know is located?
by Jasmine 3L
Fri Dec 06, 2019 3:53 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 Question 2 Help
Replies: 2
Views: 23

Test 2 Question 2 Help

Q2A: "Hydrogen bonding is important for nucleic acids. Draw how two separate nucleic acids below (guanine (G) and cytosine (C)) will interact via H-bonding to form a GC pair." - can someone explain where the H-bonds are and how they're formed? Q2.B: "There are two different base pair...
by Jasmine 3L
Fri Dec 06, 2019 3:42 pm
Forum: Electronegativity
Topic: Electronegativity of Atoms We Should Know About
Replies: 3
Views: 20

Electronegativity of Atoms We Should Know About

Can someone give a hierarchy of the electronegativities of main elements we should know about? Like I know F is the most electronegative and then O (I think?). And then there's C and S that are very similar? I would try to search up periodic tables of them but most give varying values. And I underst...
by Jasmine 3L
Fri Dec 06, 2019 3:25 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxolate Chelate
Replies: 6
Views: 32

Re: Oxolate Chelate

Oxalate is bidentate because only two of the oxygens have a minus 1 charge that they use to form a bond with the central metal atom. The other two oxygens form a double bond with the carbon so they have a neutral formal charge. Does it matter if they have a negative bond or not? For molecules like ...
by Jasmine 3L
Thu Dec 05, 2019 1:59 am
Forum: Octet Exceptions
Topic: Valence Electrons for d-block Elements (Transition Metals)
Replies: 1
Views: 19

Valence Electrons for d-block Elements (Transition Metals)

Is there a way to know how many valence electrons transition metals have? And what if it has an oxidation number? How does that affect the number of valence electrons?
by Jasmine 3L
Thu Dec 05, 2019 1:54 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Compounds and Orbitals [ENDORSED]
Replies: 1
Views: 468

Coordination Compounds and Orbitals [ENDORSED]

Perhaps this isn't relevant to what we need to know for the final but for coordination compounds, say [NiCl2(NH3)4], which orbitals (hybridized or unhybridized) do the chloride and ammonia molecules bind to on the nickel atom? Since they are all coordinate covalent bonds, I would assume the orbitals...
by Jasmine 3L
Thu Dec 05, 2019 12:47 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: best way to find out polydentate
Replies: 1
Views: 21

Re: best way to find out polydentate

Also on this problem, for part (b), solutions manual says (CO3)2- can be monodentate or bidentate because it has 2 oxygens with lone pairs and sigma bonds. Can the same be said for part (a)? Solutions manual says the molecule can be a tridentate ligand because it has 3 nitrogen atoms with lone pairs...
by Jasmine 3L
Thu Dec 05, 2019 12:22 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: best way to find out polydentate
Replies: 1
Views: 21

best way to find out polydentate

So for questions like 9C5, Which of the following ligands can be polydentate? If the ligand can be polydentate, give the maximum number of places on the ligand that can bind simultaneously to a single metal center: (a) HN(CH2CH2NH2)2; (b) CO322; (c) H2O; (d) oxalate.", what is the best way (ste...
by Jasmine 3L
Thu Dec 05, 2019 12:17 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxolate Chelate
Replies: 6
Views: 32

Oxolate Chelate

Is oxolate (C204)2- considered bidenate because two of the oxygens at the ends have single sigma bonds (so they can rotate and bind to more sites) while the other two oxygens have pi bonds (so they can't rotate and donate their electron pairs)?
by Jasmine 3L
Thu Dec 05, 2019 12:07 am
Forum: Naming
Topic: Coordination Compound Charges
Replies: 3
Views: 20

Coordination Compound Charges

For coordination compounds like in question 9C3 (Use the information in Table 9C.1 to write the formula for each of the following coordination compounds: (a) potassiumhexacyanidochromate(III) (b) pentaamminesulfatocobalt(III)chloride (c) tetraamminediaquacobalt(III) bromide (d) sodiumbisoxalato(diaq...
by Jasmine 3L
Wed Dec 04, 2019 6:18 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Need to Know About Chelating
Replies: 1
Views: 18

Need to Know About Chelating

How extensively do we need to know about chelating?
by Jasmine 3L
Wed Dec 04, 2019 3:27 am
Forum: Hybridization
Topic: Terminal Atoms
Replies: 2
Views: 21

Terminal Atoms

What are terminal atoms and do we need to know about them for the final?
by Jasmine 3L
Wed Dec 04, 2019 2:50 am
Forum: Hybridization
Topic: Unhybridized Orbitals and pi bonds
Replies: 2
Views: 21

Unhybridized Orbitals and pi bonds

Are all unpaired electrons in the unhybridized orbitals going to form a pi bond? The questions I've worked on so far that have unpaired electrons in unhybridized orbitals have a double/triple bond, which means pi bonds.
by Jasmine 3L
Wed Dec 04, 2019 2:17 am
Forum: Hybridization
Topic: sp3d and onward
Replies: 3
Views: 24

sp3d and onward

How would we draw the electron orbitals (with paired and unpaired electrons) for sp3d hybrid orbitals? I don't really know how to explain what I'm asking for so look at image haha how would I draw it for the bottom sp2d hybridization? file:///Users/jasminelouie/Pictures/Photos%20Library.photoslibrar...
by Jasmine 3L
Wed Dec 04, 2019 12:28 am
Forum: Hybridization
Topic: unhybridized orbitals?
Replies: 2
Views: 31

Re: unhybridized orbitals?

I am not quite sure how you would obtain an unhybridized orbital for hybridization. Take ethene for example, C is its central atom and its hybridization is sp^2 because of the three electron densities, but when writing it out where does the 2p orbital with an electron come from? I am very confused ...
by Jasmine 3L
Sun Dec 01, 2019 9:49 pm
Forum: Student Social/Study Group
Topic: Wednesday 11/27 Lecture
Replies: 5
Views: 54

Re: Wednesday 11/27 Lecture

Naneeta_Desar_1K wrote:Yes I can send mine to you!

Oh my goodness, thanks! My email is jasminelouie00@gmail.com
by Jasmine 3L
Sun Dec 01, 2019 12:36 am
Forum: Student Social/Study Group
Topic: Test 2 and Final
Replies: 18
Views: 103

Re: Test 2 and Final

I know the final will be cumulative but will it be heavier on the material after the midterm or...?
by Jasmine 3L
Sun Dec 01, 2019 12:34 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: What to know for the final
Replies: 8
Views: 48

Re: What to know for the final

I wouldn't think this will be on the final because all topics that are covered are in the outline. But I'm not 100% sure because Dr Lavelle usually puts an asterisk next to topics on Chemistry Community if they aren't relevant to the midterm/final. I would definitely ask to make sure.
by Jasmine 3L
Sun Dec 01, 2019 12:32 am
Forum: Bronsted Acids & Bases
Topic: What do we need to know?
Replies: 2
Views: 25

What do we need to know?

What exactly do we need to know about Bronsted acids and bases for the final? I'm kind of confused.
by Jasmine 3L
Sun Dec 01, 2019 12:31 am
Forum: Hybridization
Topic: Hybrid Orbitals
Replies: 4
Views: 25

Hybrid Orbitals

I remember one lecture example had 3 hybrid orbitals and an extra one (I forgot the name of the orbital), but there was an extra orbital with one unpaired electron because the first 3 hybrid orbitals all contained one unpaired electron. What is the reason for this extra orbital and what other times ...
by Jasmine 3L
Sun Dec 01, 2019 12:28 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Dimagnetism & Paramagnetism
Replies: 6
Views: 28

Re: Dimagnetism & Paramagnetism

I don't think we ever covered this topic so I don't think it will be tested. If anything regarding this does possible show up, I'm sure the TAs will go over it during review sessions.
by Jasmine 3L
Sun Dec 01, 2019 12:25 am
Forum: Student Social/Study Group
Topic: Preparing for the final
Replies: 25
Views: 136

Re: Preparing for the final

Similar to preparing for the midterm, I would go through lecture notes first, then through the actual textbook material and add on comments to my notes, then do all the homework problems, and then do extra practice problems provided by TAs/UAs/etc.
by Jasmine 3L
Sat Nov 30, 2019 11:59 pm
Forum: Administrative Questions and Class Announcements
Topic: Final [ENDORSED]
Replies: 10
Views: 515

Re: Final [ENDORSED]

Vincent Leong 1A wrote:The "churro" session from lyndon's last year review session expired. If anyone knows someone who has the pdf, it would be greatly appreciated if they posted it here

^!
by Jasmine 3L
Sat Nov 30, 2019 11:56 pm
Forum: Student Social/Study Group
Topic: Wednesday 11/27 Lecture
Replies: 5
Views: 54

Wednesday 11/27 Lecture

Hello,
To anyone who attended Wednesday's lecture, would you mind sharing your lecture notes with me? :( I had to fly back up to NorCal Wednesday morning so I couldn't attend lecture. Anything would be greatly appreciated!!
by Jasmine 3L
Fri Nov 22, 2019 12:45 am
Forum: Determining Molecular Shape (VSEPR)
Topic: NO Shape and Polarity
Replies: 4
Views: 33

NO Shape and Polarity

What molecular shape does NO have? N as the central atom has one bonded atom and one "lone pair", that is a single unpaired electron. Is this considered linear? And is it nonpolar since the difference if electronegativity is small?
by Jasmine 3L
Fri Nov 22, 2019 12:39 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of Diatomic Molecules
Replies: 5
Views: 26

Shape of Diatomic Molecules

What shape would diatomic molecules have? Linear?
by Jasmine 3L
Fri Nov 22, 2019 12:20 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape and Polarity
Replies: 5
Views: 26

Molecular Shape and Polarity

Does polarity of atoms in a molecule not affect its molecular shape?
by Jasmine 3L
Thu Nov 21, 2019 12:33 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Homework 3F3
Replies: 5
Views: 30

Homework 3F3

For which of the following molecules will dipole–dipole interactions be important: (a) CH4; (b) CH3Cl; (c) CH2Cl2; (d) CHCl3; (e) CCl4? Why does the lewis structure for (b) have the two chlorines at a corner and not opposite each other? Shouldn't they be opposite each other so there's less energy re...
by Jasmine 3L
Thu Nov 21, 2019 12:19 am
Forum: Electronegativity
Topic: Partial Charge
Replies: 2
Views: 21

Re: Partial Charge

Whenever there is a difference in electronegativity that is noticeable, there will be a partial negative and partial positive charge. So for instance, let's look at CCl3. Cl is very electronegative in comparison to carbon. This will cause the Cl to form a partial negative charge and C to form a par...
by Jasmine 3L
Wed Nov 20, 2019 10:59 pm
Forum: Electronegativity
Topic: Partial Charge
Replies: 2
Views: 21

Partial Charge

How do we determine if there's a partial charge or not? Would be very helpful if you can give an example that isn't water molecule H20 to explain :(
I don't know when to decide an atom has a partial charge
by Jasmine 3L
Wed Nov 20, 2019 10:21 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: Homework 3F1
Replies: 4
Views: 35

Homework 3F1

For this question "Identify the types of attractive intermolecular interactions that might arise between molecules of each of the following substances: (a) NH2OH; (b) CBr4; (c) H2SeO4; (d) SO2", is it asking what IMFs can arise if two of the same molecule (i.e. 2 of NH2OH) were to interact...
by Jasmine 3L
Wed Nov 20, 2019 10:06 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: Best Approach to Find IMFs
Replies: 11
Views: 65

Best Approach to Find IMFs

What are your best methods for finding intermolecular forces of a molecule? Do we start out with drawing the Lewis structure?
by Jasmine 3L
Wed Nov 20, 2019 5:28 pm
Forum: General Science Questions
Topic: Test 2: IMF
Replies: 4
Views: 74

Test 2: IMF

Do we need to know about ion-dipole forces and dipole-dipole forces for the test? They are sections 3F2 and 3F3 but in outline 3, it only specified 3F4 and 5. But Dr Lavelle went over ion-dipole and dipole-dipole forces in class so I'm not sure.
by Jasmine 3L
Wed Nov 20, 2019 2:34 pm
Forum: Bond Lengths & Energies
Topic: Test 2 Topics
Replies: 40
Views: 247

Re: Test 2 Topics

Test 2 covers all material since midterm up to and including the list below: • Use the Valence-Shell Electron-Pair Repulsion Model (VSEPR) to determine the shape of inorganic, organic, and small biological molecules, cations, and anions. • Use bond dipole moments and shape to determine if a molecul...
by Jasmine 3L
Wed Nov 20, 2019 2:33 pm
Forum: Administrative Questions and Class Announcements
Topic: Test #2
Replies: 22
Views: 222

Re: Test #2

Does anyone know up to which bullet point from Outline 4 (https://lavelle.chem.ucla.edu/wp-conten ... ucture.pdf) the test will cover?
by Jasmine 3L
Sun Nov 17, 2019 2:06 pm
Forum: Trends in The Periodic Table
Topic: Question
Replies: 17
Views: 82

Re: Question

505106414 wrote:Can someone explain the exception for oxygen and nitrogen? It was on the midterm and I got it wrong.

I got this question wrong too :(
by Jasmine 3L
Sun Nov 17, 2019 2:04 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: Quick Run-Through
Replies: 2
Views: 20

Quick Run-Through

Can someone give explanations of each of these intermolecular forces and how to identify them? I'm having trouble understanding how to distinguish them and how to find them in Lewis structures. Please provide examples if possible! Thank you!
by Jasmine 3L
Sun Nov 17, 2019 1:59 pm
Forum: Empirical & Molecular Formulas
Topic: empirical = molecular?
Replies: 15
Views: 119

Re: empirical = molecular?

There is always a molecular formula and empirical formula for a compound. The molecular formula accounts for ALL of the numbers of atoms in that compound while the empirical formula is a simplified version (but only simplified to whole numbers, no decimals or fractions). The molecular formula will b...
by Jasmine 3L
Sun Nov 17, 2019 1:57 pm
Forum: SI Units, Unit Conversions
Topic: Memorizing Conversions
Replies: 23
Views: 151

Re: Memorizing Conversions

Most of the complicated conversions you don't need to memorize it because they are given in the constant/equation sheet (check it out on Dr Lavelle's website). But if you find a conversion you think you will need for the final that isn't on the sheet, then yeah memorize it.
by Jasmine 3L
Sun Nov 17, 2019 1:55 pm
Forum: Significant Figures
Topic: Sig Figs on Tests
Replies: 24
Views: 187

Re: Sig Figs on Tests

When using dimensional analysis throughout the problem, make sure to use ALL the numbers given in the periodic table and constant/equation sheet. When you get a final answer after keeping ALL numbers throughout, you will round to the least amount of significant figures given in the actual problem.
by Jasmine 3L
Sun Nov 17, 2019 1:49 pm
Forum: Student Social/Study Group
Topic: Test 2 Study Worksheets
Replies: 9
Views: 184

Test 2 Study Worksheets

Are there any UA worksheets, or any worksheets with practice problems in general, focused on the materials that will tested on Test 2?
by Jasmine 3L
Sun Nov 17, 2019 1:46 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: AXE formula
Replies: 32
Views: 1443

Re: AXE formula

Yes it is! Any molecule with the same AXE formula will have the same molecular shape/
by Jasmine 3L
Sun Nov 10, 2019 12:29 pm
Forum: Bond Lengths & Energies
Topic: polarizability
Replies: 9
Views: 20

Re: polarizability

I don't really understand this too. Like how does it relate to melting and boiling point?
by Jasmine 3L
Sun Nov 10, 2019 12:25 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarisability
Replies: 4
Views: 14

Re: Polarisability

An atom has high polarizing power if they are likely to cause the electron distortion of another atom. And these are usually small, highly-charged cations (so elements in the upper left of the periodic table). An atom is highly polarizable if they are likely to have their electron distorted. These a...
by Jasmine 3L
Sun Nov 10, 2019 12:21 pm
Forum: Resonance Structures
Topic: Unequal Contribution
Replies: 3
Views: 50

Re: Unequal Contribution

I don't think there's a specific way to draw resonance structures that don't contribute to the resonance hybrid equally. I think you just need to draw out all the possible resonance structures and specifically state which ones contribute more (the ones with lowest formal charges) and which ones don'...
by Jasmine 3L
Sun Nov 10, 2019 12:18 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 18
Views: 64

Re: Drawing Lewis Structures

You don't always need to write in the atom's formal charges next to elements but you should always draw them in consideration of formal charges because formal charges closest to 0 means the molecule is most stable, which is what we are aiming for. But don't just draw them so everything has a formal ...
by Jasmine 3L
Sun Nov 10, 2019 12:16 pm
Forum: Sigma & Pi Bonds
Topic: Triple bond?
Replies: 18
Views: 482

Re: Triple bond?

Sana_Mian_3G wrote:If there is a triple bond how many pi and sigma bonds are there?

I'm confused. What are pi and sigma bonds? Were they discussed in lecture because I don't remember about it.
by Jasmine 3L
Sun Nov 10, 2019 12:15 pm
Forum: Bond Lengths & Energies
Topic: Interaction Potential Energy Formula
Replies: 2
Views: 19

Interaction Potential Energy Formula

Do we need to memorize the formula for interaction potential energy (the proportionality formula) or do we just need to remember how the variables relate to each other, say, how the radius affects interaction potential energy?
by Jasmine 3L
Wed Nov 06, 2019 1:45 am
Forum: General Science Questions
Topic: Midterm: Paramagnetic and Diamagnetic
Replies: 1
Views: 28

Midterm: Paramagnetic and Diamagnetic

Do we need to know these concepts for midterm? I was going through UA worksheets and I see questions on paramagnetic and diamagnetic but it wasn't covered in the required readings and not in questions in Outline 3.
by Jasmine 3L
Tue Nov 05, 2019 12:13 pm
Forum: Octet Exceptions
Topic: Homework Problem 2.C.3
Replies: 2
Views: 35

Homework Problem 2.C.3

Can someone tell me how to solve this problem? Draw the Lewis structure, including typical contributions to the resonance structure (where appropriate, allow for the possibility of octet expansion, including double bonds in different positions), for (a) periodate ion; (b) hydrogen phosphate ion; (c)...
by Jasmine 3L
Mon Nov 04, 2019 5:57 pm
Forum: Trends in The Periodic Table
Topic: Effective Nuclear Charge
Replies: 5
Views: 45

Re: Effective Nuclear Charge

Effective nuclear charge plays a role in the atomic radius. As you move across a period, the effective nuclear charge increases, meaning the positive charge has a larger effect in pulling in outer electrons, therefore decreasing the atomic radius. Hope that helps. I can see how additional electrons...
by Jasmine 3L
Sun Nov 03, 2019 9:23 pm
Forum: *Shrodinger Equation
Topic: Schrondiger's Equation
Replies: 6
Views: 39

Re: Schrondiger's Equation

Honestly, I don't know how much we need to know about this because in Outline 2, it says to omit 1C, which is on the wave function but the TA in today's review session was discussing the wave equation.
by Jasmine 3L
Sun Nov 03, 2019 9:19 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Aufbau vs Hunds
Replies: 6
Views: 35

Re: Aufbau vs Hunds

Aufbau Principle is the building-up principle. You need to occupy the lowest energy level before going higher in energy. We always want the lowest energy electron configuration.
by Jasmine 3L
Sun Nov 03, 2019 9:16 pm
Forum: Octet Exceptions
Topic: Why do these not have octets?
Replies: 3
Views: 40

Re: Why do these not have octets?

For Part C, there is a triple bond between the carbon and the oxygen, and again, each atom has one lone pair. The formal charge works out to be +1 for the oxygen and -1 for the carbon. In the same manner that the octets for Part A are fulfilled, the octets are also fulfilled for the triple bond bet...
by Jasmine 3L
Sun Nov 03, 2019 9:14 pm
Forum: Lewis Structures
Topic: Best way to go about drawing Lewis structures
Replies: 7
Views: 45

Re: Best way to go about drawing Lewis structures

Thanks for the help! Nice to know that everyone is doing trial and error like me.
by Jasmine 3L
Sun Nov 03, 2019 9:13 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in Position and Uncertainty in Momentum
Replies: 4
Views: 47

Re: Uncertainty in Position and Uncertainty in Momentum

I have the same issue understanding this concept. I understand how it works mathematically using the Heisenberg indeterminacy equation, but I do not quite understand it conceptually. If there is more uncertainty regarding the position, shouldn't there be more uncertainty about the momentum as well?...
by Jasmine 3L
Sat Nov 02, 2019 11:08 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty in Position and Uncertainty in Momentum
Replies: 4
Views: 47

Uncertainty in Position and Uncertainty in Momentum

I understand why uncertainty in momentum would lead to uncertainty in position (because we don't know which pathway electrons take after being perturbed by a photon). But why is it that the more precise we know about the position, the less we know about the momentum at that instant?
by Jasmine 3L
Fri Nov 01, 2019 2:03 am
Forum: Lewis Structures
Topic: Best way to go about drawing Lewis structures
Replies: 7
Views: 45

Best way to go about drawing Lewis structures

So is the best way to draw Lewis structures is 1) count all valence e- 2) choose atom with lowest ionization energy as central atom 3) arrange the rest of the atoms around the central atom 4) draw covalent bonds and unpaired e- that adds up to the number in Step 1 5) calculate the formal charges to ...
by Jasmine 3L
Fri Nov 01, 2019 1:52 am
Forum: Octet Exceptions
Topic: Why do these not have octets?
Replies: 3
Views: 40

Why do these not have octets?

In problem 2B.19 "Draw the Lewis structure and determine the formal charge on each atom in (a) NO+; (b) N2; (c) CO; (d) C222; (e) CN2.", I drew NO+ with a double bond between N and O, and N has 1 lone pair and O has 2 lone pairs. Calculating the formal charges of N and O, this is the best ...
by Jasmine 3L
Fri Nov 01, 2019 1:40 am
Forum: Octet Exceptions
Topic: Expanded Valence Shells
Replies: 3
Views: 39

Expanded Valence Shells

How do we know how many electrons elements with expanded valence shells can hold? Like in the example from lecture, the slide says "P in phosphorus pentachloride PCl5 has 10 valence e- (s2p6d2) using 1 d-orbital". How do we know that phosphorus can hold 10 valence electrons? And from a hom...
by Jasmine 3L
Thu Oct 24, 2019 2:40 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty value in equation
Replies: 9
Views: 45

Re: Uncertainty value in equation

Yes because the "range of uncertainty" if you would call it that, or margin of uncertainty, is +/- 3 so it's basically the absolute value of 3 times 2.
by Jasmine 3L
Thu Oct 24, 2019 2:38 am
Forum: Quantum Numbers and The H-Atom
Topic: Balmer and Lyman Series
Replies: 6
Views: 44

Re: Balmer and Lyman Series

The Balmer Series and Lyman Series are basically the names for these sets of lines on the spectral emission gradient(?) that corresponds to specific amounts of wavelength needed to cause an electronic transition from one state to the next. So for the Balmer Series, all the lights have a wavelength t...
by Jasmine 3L
Thu Oct 24, 2019 2:30 am
Forum: Trends in The Periodic Table
Topic: 2nd Ionization Energy
Replies: 7
Views: 35

Re: 2nd Ionization Energy

The way I thought of it was with the element Fluorine as an example. Fluorine has 1 valence electron. After the first ionization energy is used(?) (I don't know if used is the correct word for this) to remove that valence electron, the rest of Fluorine's electrons is in an octet, where the electrons...
by Jasmine 3L
Thu Oct 24, 2019 2:26 am
Forum: Administrative Questions and Class Announcements
Topic: KAREN SUN 5-7PM WORKSHOP - DOWNLAOD WORKSHEETS HERE
Replies: 53
Views: 2162

Re: KAREN SUN 5-7PM WORKSHOP - DOWNLAOD WORKSHEETS HERE

Does anyone know if any other UAs post their worksheets on Chemistry Community?? These worksheets are so helpful especially for me whose high school chemistry background is essentially nonexistent.
Thank you so much Karen for posting these!
by Jasmine 3L
Thu Oct 24, 2019 2:24 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Lowest Energy for Elements, Compounds, Etc
Replies: 2
Views: 30

Lowest Energy for Elements, Compounds, Etc

Sorry if this is a dumb question but why do we want the electron configuration to show the lowest energy again? Like why have the valence electrons in calcium be in the 4s state and not the 3d state? The same goes for chemical bonding. Why do we want to achieve the lowest energy (whether it is by io...
by Jasmine 3L
Thu Oct 24, 2019 2:20 am
Forum: Lewis Structures
Topic: Double Bonds and Electron Numbers
Replies: 4
Views: 45

Double Bonds and Electron Numbers

Don't know if this question is for Lewis Structures or Resonance but here we go anyways. Can someone explain how double covalent bonds change the number of electrons of a compound? Like why does making one of the NO bonds a double covalent bond for the compound NO3- change the number of valence elec...
by Jasmine 3L
Thu Oct 24, 2019 2:14 am
Forum: Trends in The Periodic Table
Topic: Location of elements
Replies: 12
Views: 75

Re: Location of elements

I don't think we need to remember exactly what metals are part of which group but if you are given the general region the element is on the periodic table, I think you should be able to know because they are grouped pretty easily. But I do think you should know the basics like oxygen, nitrogen, carb...
by Jasmine 3L
Thu Oct 24, 2019 2:12 am
Forum: Properties of Light
Topic: Threshold Frequency
Replies: 5
Views: 35

Re: Threshold Frequency

Threshold energy for the photoelectric effect (shining light on a metal surface and observing whether or not electrons were ejected) is the minimum amount of energy required to remove an electron from the metal surface. Threshold frequency would then be the minimum frequency of the light that gives ...
by Jasmine 3L
Thu Oct 24, 2019 12:39 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: ground state
Replies: 6
Views: 48

Re: ground state

I would suggest you print or create a blank electron configuration worksheet with boxes for each orbital, subshell, etc (like the first part of this website >> https://sites.google.com/a/usd411.org/chemistry/unit2a/notes/k). You will be able to see how each elements electron configuration is "m...
by Jasmine 3L
Thu Oct 17, 2019 2:06 am
Forum: Properties of Light
Topic: Rydberg's Equation [ENDORSED]
Replies: 4
Views: 26

Re: Rydberg's Equation [ENDORSED]

From what I noticed, you mainly use the Rydberg Equation in questions that ask about the electronic transition levels, so when the electron goes from n=1 to n=3 state for example.
by Jasmine 3L
Thu Oct 17, 2019 2:04 am
Forum: Quantum Numbers and The H-Atom
Topic: spin up and spin down
Replies: 7
Views: 34

Re: spin up and spin down

The numbers are arbitrary so you don't need to worry all too much about it. Just focus on the sign of the number and you will know if the electron spins up or down.
by Jasmine 3L
Sun Oct 13, 2019 1:04 pm
Forum: Photoelectric Effect
Topic: Problem 1.15
Replies: 1
Views: 23

Problem 1.15

I don't know if this is the right place for this question but for Problem 1.15, it's asking for the initial and final energy levels. And the answer is a transition from n1=1 to n2=3. So does this mean the final state is 3 and the initial state is 1?
by Jasmine 3L
Sun Oct 13, 2019 10:55 am
Forum: Balancing Chemical Reactions
Topic: F.3
Replies: 5
Views: 37

Re: F.3

I had the same worry as you. I saw so much practice problems asking us to name compounds and such, and with my super weak high school chem background, I immediately went to Fundamental Section D to read all about nomenclature. It provides very good explanations on how to name simple compounds, like ...
by Jasmine 3L
Sun Oct 13, 2019 10:53 am
Forum: Empirical & Molecular Formulas
Topic: Nomenclature
Replies: 11
Views: 76

Re: Nomenclature

I have the same worry about you because there are just so many compounds in this world to know everything. But I think it's good to know the basic rules of basic compounds. Check the fundamental section D in the textbook. That section helped me so much preparing for the test (even though we ended up...
by Jasmine 3L
Sun Oct 13, 2019 10:50 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 2331

Re: Test 1 [ENDORSED]

omg i'm going to be so annoyed with myself if they had the angstrom conversion on the front page. I think I did the conversion correctly but I wasn't 100% sure during the test is it was 10x10^-10 m or not but I just went with it. I guess it's a lesson of learning to utilize all provided resources. ...
by Jasmine 3L
Sun Oct 13, 2019 10:47 am
Forum: Significant Figures
Topic: Sig Figs at the Beginning or End
Replies: 14
Views: 93

Re: Sig Figs at the Beginning or End

AT THE END! Do your best to keep as many figures as possible throughout your work. One way I do this if I do the problem on paper is writing an excess amount of figures (usually at least 3 more sig figs than needed) and then using that number in the next calculation. Once you get the final answer, r...
by Jasmine 3L
Sun Oct 13, 2019 10:45 am
Forum: SI Units, Unit Conversions
Topic: Practice Problems?
Replies: 11
Views: 139

Re: Practice Problems?

It's on Dr Lavelle's Chemistry website! https://lavelle.chem.ucla.edu/class-websites/chem14a/ make sure to put in the password that he provided in his earlier emails. Just scroll down to Learning Outcomes and the problems for fundamentals is Outline 1 >>> https://lavelle.chem.ucla.edu/wp-content/sup...
by Jasmine 3L
Sun Oct 13, 2019 10:43 am
Forum: Limiting Reactant Calculations
Topic: About Finding Limiting Reactant
Replies: 7
Views: 48

Re: About Finding Limiting Reactant

Honestly, you can leave it either in moles or convert to grams since you are only asking to find the limiting reactant. The limiting reactant would just be which reactant produces a lesser amount of product (moles or grams). But do keep in mind that if the question asks for how much product it can p...
by Jasmine 3L
Thu Oct 10, 2019 12:09 am
Forum: Molarity, Solutions, Dilutions
Topic: Problem G13
Replies: 2
Views: 67

Problem G13

Hello, can someone explain part B of problem G13? (b) An experiment requires the use of 60.0 mL of 0.50 M NaOH(aq). The stockroom assistant can only find a reagent bottle of 2.5 M NaOH(aq). How can the 0.50 M NaOH(aq) be prepared? From the solutions manual, I understand why 12ml of the 2.5 M NaOH(aq...
by Jasmine 3L
Tue Oct 08, 2019 10:45 pm
Forum: Significant Figures
Topic: Significant Figures for Test 1
Replies: 3
Views: 44

Significant Figures for Test 1

I was wondering when they (graders) want us to round to sig figs. Because the textbook and the sigfig pdf Dr. Lavelle posted on his website says to only round at the final step. But when I keep all numbers during multiple-step calculations on the textbook problems, my final answer ends up being wron...
by Jasmine 3L
Thu Oct 03, 2019 1:01 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 128
Views: 2317

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

First off, thanks so much for sharing your story and experience! It's always so nice to hear alumni talk about their past and present experiences. I'm not sure if any of the other students already asked this, but I was wondering what other extracurriculars did you do at UCLA other than being a UA fo...
by Jasmine 3L
Thu Oct 03, 2019 12:54 am
Forum: Significant Figures
Topic: Does molar mass count for sig figs?
Replies: 6
Views: 76

Re: Does molar mass count for sig figs?

It doesn't count for sig figs but I think Dr. Lavelle just likes to round it off (round 15.999 g/mol for O to 16) for lecture to make things simple. But definitely when doing calculations, try to keep all numbers and round off until the end.
by Jasmine 3L
Mon Sep 30, 2019 8:41 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula
Replies: 7
Views: 40

Re: Empirical Formula

It isn't necessary to say the mass is 100g. It just makes the calculations much easier because we use mass percentage composition and percentages are 100.
by Jasmine 3L
Mon Sep 30, 2019 8:38 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Mole ratios
Replies: 4
Views: 61

Re: Mole ratios

If I am not wrong, things like balanced equations and empirical/molecular formulas need to contain whole numbers. But for what you asked about "you have 0.018 mol NaCl in a NaCl + H2O solution", I think that you can have 0.018 mol of a certain compound because 1 mole doesn't mean 1 atom (f...
by Jasmine 3L
Mon Sep 30, 2019 8:23 pm
Forum: SI Units, Unit Conversions
Topic: Writing Compound Formulas
Replies: 3
Views: 56

Writing Compound Formulas

Honestly, I don't know which is the correct place for this topic but this seems to be the best place. Anyways, I was wondering how to figure out what the formulas for compounds are through their names. For example, question E9, says "Epsom salts consist of magnesium sulfate heptahydrate. Write ...
by Jasmine 3L
Mon Sep 30, 2019 8:03 pm
Forum: Balancing Chemical Reactions
Topic: Combustion Equation
Replies: 21
Views: 863

Re: Combustion Equation

Yes! Because combustion reactions mean the hydrocarbon (the CH variant reactant) is oxidized (reacts with oxygen) to break down the hydrocarbon and produce carbon dioxide and water.
by Jasmine 3L
Mon Sep 30, 2019 6:32 pm
Forum: Molarity, Solutions, Dilutions
Topic: Symbol for Molarity
Replies: 7
Views: 70

Re: Symbol for Molarity

In my experience, the easiest way to distinguish between the molar mass and molarity of a solution is the context of the question, but do remember that the textbook also uses c for molarity of a solution. And sometimes they may even through in the units of the answer that they want so if they say g/...
by Jasmine 3L
Mon Sep 30, 2019 6:25 pm
Forum: Limiting Reactant Calculations
Topic: Determining Limiting Reactant by Mole or Mass
Replies: 8
Views: 76

Re: Determining Limiting Reactant by Mole or Mass

Honestly, my high school chemistry background is quite terrible but in my opinion, I think both way definitely works since you can always convert between mass and moles. But I strongly agree with the above answer. Using moles is very efficient when using the balanced equation because you can see the...

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