Search found 51 matches
- Wed Dec 04, 2019 10:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape vs. Molecular Geometry
- Replies: 4
- Views: 341
Re: Molecular Shape vs. Molecular Geometry
Geometry refers to the arrangements of regions of electron density around an atom (a.k.a. coordination number; lone pairs + bonds). Shape doesn't account for lone pairs.
- Wed Dec 04, 2019 10:19 pm
- Forum: Naming
- Topic: Naming with Latin names
- Replies: 1
- Views: 174
Re: Naming with Latin names
I think we're expected to know these special cases. Another one that comes to mind is ferrate, but the other transition metal names should be more straightforward!
- Wed Dec 04, 2019 10:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: How do you tell if parts of a molecule are in the same plane?
- Replies: 2
- Views: 348
Re: How do you tell if parts of a molecule are in the same plane?
Shape (& kind of bond angles)! Different molecule shapes have different planes. For example, trigonal planar atoms are all in the same single plane (120 degrees apart). However, octahedral molecules have 4 equatorial atoms in one plane, and the 2 axial atoms in another. I would try to imagine th...
- Wed Dec 04, 2019 10:11 pm
- Forum: Naming
- Topic: Parentheses
- Replies: 1
- Views: 193
Re: Parentheses
I think it's just to make the name less confusing. Both oxalato and aqua are multi-atom ligands so they might just sometimes be in parantheses.
- Mon Dec 02, 2019 11:53 am
- Forum: Calculating the pH of Salt Solutions
- Topic: 6D.11 F
- Replies: 2
- Views: 211
Re: 6D.11 F
The answer key says the solution is actually more acidic! The equation it has is Cu(H2O)63+ (aq) + H2O (l) ⇋ H3O+ (aq) + Cu(H2O)5OH+ (aq)
- Sat Nov 30, 2019 6:00 pm
- Forum: Naming
- Topic: Naming Coordinate Compounds
- Replies: 2
- Views: 218
Re: Naming Coordinate Compounds
First, if you haven't memorized the ligand list Dr. Lavelle posted, do that! The ligand names are the basis of coordinate compound nomenclature, and you'll know they're ligands if they're inside the brackets. Second, I would re-familiarize myself with the prefixes (di-, tri-, tetra-, etc.). Then, wh...
- Sat Nov 30, 2019 3:18 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 2
- Views: 172
Re: Hybridization
A simple way to think about it is the number of hybrid orbitals = the number of regions of electron density (e.g. 3 bonds + 1 lone pair = 4 regions). And it basically goes sp, sp2, sp3, sp3d, sp3d2 etc. sp means two regions, sp2 = 3, sp3 = 4 etc.
- Sat Nov 30, 2019 3:16 pm
- Forum: Student Social/Study Group
- Topic: Final
- Replies: 2
- Views: 205
Re: Final
Dr. Lavelle just sent an email saying that he'll go over the last examples at the beginning of Wednesday's lecture, so I'm assuming that's the last bit of content left. Afterwards, it's just going to be review.
- Sat Nov 30, 2019 3:13 pm
- Forum: Student Social/Study Group
- Topic: midterm 6a
- Replies: 1
- Views: 192
Re: midterm 6a
I was wondering about this too. Should it be six electrons?
- Sat Nov 30, 2019 3:10 pm
- Forum: Hybridization
- Topic: Lyndons Worksheet Question 2
- Replies: 1
- Views: 214
Re: Lyndons Worksheet Question 2
You're right actually! It should be O2sp 2 , my bad. And for the double bonded O: iirc it wants to make sigma bonds first, so its stabler hybrid orbitals are used in making the sigma bond. The pi bond is then formed with the leftover unhybridized 2p orbital. This happens because the electron wants t...
- Fri Nov 22, 2019 2:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 9 Homework
- Replies: 2
- Views: 180
Re: Week 9 Homework
I think we would probably turn it in along with next homework!
- Fri Nov 22, 2019 2:34 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Acids
- Replies: 6
- Views: 428
Re: Acids
A strong Bronsted acid is one that is more readily to donate a proton, while a weak Bronsted acid is less willing to give up its proton(s).
- Fri Nov 22, 2019 2:33 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Naming Ligands
- Replies: 2
- Views: 236
Re: Naming Ligands
I would assume so! He spent a good portion of lecture discussing all the rules, and Outline 5 says "be familiar with the rules for naming coordination compounds."
- Fri Nov 22, 2019 2:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Homework 2.27
- Replies: 1
- Views: 170
Re: Homework 2.27
No, you're right. The solutions guide says that they're all diamagnetic (paired electrons)!
- Fri Nov 22, 2019 12:19 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Removing Non-Axis Atoms First
- Replies: 4
- Views: 363
Re: Removing Non-Axis Atoms First
Axial atoms are removed first only for molecules with octahedral electron geometry i.e. 8 regions of electron density. This is because this particular arrangement minimizes electron-electron repulsion, especially if there are two lone pairs (they'd be on opposite sides of the molecule). However, eq...
- Thu Nov 14, 2019 8:51 pm
- Forum: Dipole Moments
- Topic: Test 2
- Replies: 3
- Views: 312
Re: Test 2
I would imagine so - I feel like it would probably be on all the material we've covered since the midterm leading up to the test day.
- Thu Nov 14, 2019 8:49 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing power vs polarizability
- Replies: 5
- Views: 1017
Re: Polarizing power vs polarizability
Polarizing power = cation's ability to distort electron region of anion
Polarizability = anion's tendency to be distorted
Polarizability = anion's tendency to be distorted
- Thu Nov 14, 2019 8:48 pm
- Forum: Dipole Moments
- Topic: Dipole Moment to figure out polarity
- Replies: 3
- Views: 267
Re: Dipole Moment to figure out polarity
Overall molecular polarity is determined by the net dipole, which is equal to the sum of all the individual bond dipoles (i.e. the electronegativity differences between two bonded atoms). For example, if an atom has a much stronger bond dipole towards one side, then that molecule has a net dipole an...
- Thu Nov 14, 2019 8:45 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: hw problem 2D.11
- Replies: 2
- Views: 288
Re: hw problem 2D.11
The larger the anion (in terms of atomic size), the more loosely the electrons are held by the nucleus. This allows the electrons to be more easily distorted by a cation. A greater tendency to be distorted = polarizability. In short, polarizability increases with atomic size. Hopefully this gives yo...
- Wed Nov 13, 2019 3:34 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: H-bonding & Dipole-Dipole (Problem 3F.1)
- Replies: 4
- Views: 304
H-bonding & Dipole-Dipole (Problem 3F.1)
On homework problem 3F.1a and c, both molecules have all three intermolecular forces (dispersion forces, hydrogen bonding, & dipole-dipole). I was just wondering, if a molecule exhibits hydrogen bonding, does that mean they will also have dipole-dipole forces by default?
- Tue Nov 05, 2019 10:06 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration
- Replies: 3
- Views: 319
Re: Electron Configuration
The configuration always goes from low to high in terms of n, so it would still be 3d104s1.
- Tue Nov 05, 2019 9:34 am
- Forum: Lewis Structures
- Topic: lewis structure homework help
- Replies: 2
- Views: 214
Re: lewis structure homework help
I don't think we'll have to know nomenclature until later when we'll actually be taught it! I just looked up the chemical formula for each ion and then drew the structures. As for the problem itself, halogens can expand their octet, meaning they don't necessarily form only 4 bonds. If they have 7 va...
- Tue Nov 05, 2019 9:30 am
- Forum: Resonance Structures
- Topic: Resonance Hybrids
- Replies: 3
- Views: 165
Re: Resonance Hybrids
A hybrid structure is an average of all the molecule's resonance forms/structures! And if the question asks to draw all the resonance forms of a molecule, which it usually does, you would just draw out each form (not the hybrid structure). I think we usually draw out each individual resonance form a...
- Mon Nov 04, 2019 6:45 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Electron Configuration
- Replies: 5
- Views: 280
Re: Midterm Electron Configuration
It might not be on the midterm, but I would at least know how to write the configuration for an atom with 4f electrons (first row with f-block).
- Mon Nov 04, 2019 6:43 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic
- Replies: 3
- Views: 237
Re: Ionic
I think the electronegativity values would probably be given to us if it weren't obvious just using periodic trends
- Tue Oct 29, 2019 3:34 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 5 HW
- Replies: 4
- Views: 309
Week 5 HW
Which problems are okay for this week's homework? Can it only be from the Chemical Bonds unit or can we also do quantum problems?
- Mon Oct 28, 2019 10:57 am
- Forum: Trends in The Periodic Table
- Topic: Electronegativity vs. Electron affinity
- Replies: 8
- Views: 537
Re: Electronegativity vs. Electron affinity
There's a post from last year on the same topic: https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=35085
I think it has to do more with whether the atoms in question are bonded or not. However, they do have the same trend (increasing across, decreasing down).
I think it has to do more with whether the atoms in question are bonded or not. However, they do have the same trend (increasing across, decreasing down).
- Mon Oct 28, 2019 10:53 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: In Class Example, Sulfate
- Replies: 3
- Views: 377
Re: In Class Example, Sulfate
It has to do with electron affinity. Atoms with lower affinities are less likely to have a stable negative formal charge because they're less likely to want to hold onto an added electron. Since electron affinity tends to decrease down a group, sulfur has a lower affinity than oxygen, and therefore ...
- Mon Oct 28, 2019 10:44 am
- Forum: General Science Questions
- Topic: midterm review sessions
- Replies: 1
- Views: 117
Re: midterm review sessions
I think they're cancelled at least for today. Someone emailed one of the TAs and they said they wouldn't be happening.
- Mon Oct 28, 2019 10:44 am
- Forum: Lewis Structures
- Topic: Lewis Structure
- Replies: 2
- Views: 113
Re: Lewis Structure
Yep! Atoms, molecules, or ions with one unpaired electron are called free radicals. They're highly unstable and usually very reactive
- Mon Oct 28, 2019 10:42 am
- Forum: Administrative Questions and Class Announcements
- Topic: Review Sessions
- Replies: 2
- Views: 149
Re: Review Sessions
No, someone emailed one of the TAs and they said they would be cancelled.
- Mon Oct 21, 2019 3:20 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Test Question
- Replies: 3
- Views: 160
Re: Test Question
I think they're majority problem solving i.e. using equations and making calculations. However, the select questions on the homework that require explanation make me think that there might be more conceptual questions later on. The last test was mainly calculations since the content we covered was m...
- Mon Oct 21, 2019 3:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Format
- Replies: 11
- Views: 438
Midterm Format
I know it's still weeks away but I was wondering, does anyone know about the format of the midterm? Is it comparable to Test 1 but just longer in length? What types of questions will be on it and which units does it cover?
- Mon Oct 21, 2019 3:12 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Exceptions (Cr and Cu)
- Replies: 3
- Views: 135
Re: Exceptions (Cr and Cu)
I think it would probably occur in groups 6 and 7 as well, in addition to some similar electron transferring in the f orbital. But like Dr. Lavelle said, we won't really have to worry about the details past Cr and Cu!
- Mon Oct 21, 2019 3:08 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: orbitals
- Replies: 5
- Views: 139
Re: orbitals
I don't think we need to know the orbital shapes/planes in detail enough to be able to draw them out. I agree with Brian said though - just remember that s orbitals don't have a node while the other orbitals do. That would probably be it though.
- Mon Oct 21, 2019 3:07 pm
- Forum: *Shrodinger Equation
- Topic: Week 4 Homework
- Replies: 3
- Views: 124
Re: Week 4 Homework
Yep! We're still learning content from the quantum unit this week so I would assume quantum homework works
- Sun Oct 20, 2019 3:03 pm
- Forum: Properties of Light
- Topic: Modules
- Replies: 5
- Views: 239
Re: Modules
I don't think so - those modules were all made at once probably a while back. They're probably just there to help us ease into the class/review some commonly confused concepts.
- Sun Oct 20, 2019 3:01 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Symmetry within the Orbitals
- Replies: 3
- Views: 207
Re: Symmetry within the Orbitals
The symmetry just describes the shape of the orbitals. S the only symmetric one because it is spherical. The other orbitals have shapes that are not symmetric. Not sure what the orbital symmetry tells us though
- Sun Oct 20, 2019 2:54 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: 1D.1
- Replies: 5
- Views: 214
Re: 1D.1
Which of the following increase when the electron in a hydrogen atom undergoes a transition from the 1s-orbital to a 2p-orbital? (a) Energy of the electron. (b) Value of n. (c) Value of l. (d) Radius of the atom. Not entirely sure, but I think all of them increase because: (a) the electron must abs...
- Sun Oct 20, 2019 2:47 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Accessing the E-textbook [ENDORSED]
- Replies: 125
- Views: 26624
Re: Accessing the E-textbook [ENDORSED]
Does anyone know what the Sapling learning thing is? I heard it was extra practice but I was wondering how to access it/what kind of practice it was.
- Sun Oct 20, 2019 1:59 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Filling d orbital with s electrons
- Replies: 1
- Views: 95
Filling d orbital with s electrons
I understand that, in the case of elements like copper and silver, the s orbital electrons will donate an electron to the d orbital to achieve a full orbital. But I was wondering, why does this happen? Is a full d orbital more stable than an unfilled s orbital?
- Fri Oct 11, 2019 12:12 pm
- Forum: Properties of Light
- Topic: Amplitude
- Replies: 12
- Views: 500
Re: Amplitude
Amplitude isn't all that important for these calculations. However, amplitude of a wave is the same as intensity of light.
- Fri Oct 11, 2019 12:11 pm
- Forum: Properties of Electrons
- Topic: Energy Level Relationship
- Replies: 4
- Views: 114
Re: Energy Level Relationship
He said that as the energy level increased, E (the energy) decreases. Basically as n approaches infinite, E approaches zero. This is because n increasing means the electrons are moving further away from the nucleus, so the interaction between the electrons and the nucleus, E, decreases and approach...
- Fri Oct 11, 2019 12:05 pm
- Forum: DeBroglie Equation
- Topic: Frequency and de Broglie Equation Derivation
- Replies: 3
- Views: 185
Frequency and de Broglie Equation Derivation
During lecture today, it was mentioned that the frequency (from the E=hv equation) can't be calculated for de Broglie wavelengths since those are for electromagnetic radiation, not electrons. However, the de Broglie equation was derived from E=hv so I was wondering, do the electrons have a frequency...
- Fri Oct 11, 2019 11:59 am
- Forum: DeBroglie Equation
- Topic: Measurable V. Non-Measurable
- Replies: 5
- Views: 159
Re: Measurable V. Non-Measurable
Any de Broglie wavelength less than 10–15 is typically not going to have experimentally detectable wavelike properties, making it more particle-like.
- Mon Oct 07, 2019 3:24 pm
- Forum: Properties of Light
- Topic: Light intensity
- Replies: 10
- Views: 353
Re: Light intensity
I think that light intensity is independent of the other two values. In a particle model of light, intensity is just the number of photons (e.g. higher intensity means more photons and thus more electrons ejected). In a wave model, intensity is just the amplitude. This is the post I referenced: http...
- Wed Oct 02, 2019 10:45 pm
- Forum: SI Units, Unit Conversions
- Topic: Question about final answers on tests
- Replies: 8
- Views: 466
Re: Question about final answers on tests
I think it's a good idea to include them if you can! My TA mentioned that they sometimes take off points if you don't.
- Wed Oct 02, 2019 10:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test #1
- Replies: 2
- Views: 130
Re: Test #1
It should be on just fundamentals!
- Mon Sep 30, 2019 2:53 pm
- Forum: SI Units, Unit Conversions
- Topic: Formula units vs molecules vs atoms? [ENDORSED]
- Replies: 7
- Views: 283
Re: Formula units vs molecules vs atoms? [ENDORSED]
I am still confused on the concept of formula units. How many formula units would be in 46g of NaCl? According to the explanations on this page, I'm assuming it would be the number of NaCl "molecules" in 46g. I put molecules in quotations since NaCl wouldn't be a single molecule in real l...
- Mon Sep 30, 2019 2:49 pm
- Forum: SI Units, Unit Conversions
- Topic: Formula units vs molecules vs atoms? [ENDORSED]
- Replies: 7
- Views: 283
Re: Formula units vs molecules vs atoms? [ENDORSED]
A formula unit is the empirical formula of any ionic solid (or covalent network solid). Since these solids (ex. NaCl or SiO2) don't exist as individual molecules, we use the term "formula unit" instead. In the example you stated, alumina is an ionic compound so the technically correct uni...
- Fri Sep 27, 2019 9:57 pm
- Forum: SI Units, Unit Conversions
- Topic: Formula units vs molecules vs atoms? [ENDORSED]
- Replies: 7
- Views: 283
Formula units vs molecules vs atoms? [ENDORSED]
What exactly is the difference between formula units, molecules, and atoms? And what is a formula unit in general? How would you calculate the number of formula units given a compound's mass? For reference, this is the HW question I'm referring to (Fundamentals E) E.21 Calculate the amount (in moles...