Search found 35 matches

by Robert Cross 1A
Sun Nov 17, 2019 11:23 pm
Forum: Bond Lengths & Energies
Topic: Test 2 Topics
Replies: 39
Views: 195

Re: Test 2 Topics

KSong_3C wrote:I think it’s just everything we learn after the midterm!
I think it's on everything that wasn't on the midterm that we learned before the midterm + what we learned after the midterm
by Robert Cross 1A
Sun Nov 17, 2019 11:18 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 50
Views: 340

Re: Study Tips

For the current VSEPR material, I found that flashcards were helpful in learning the various molecule configurations and shapes, so I'd have to recommend those
by Robert Cross 1A
Sun Nov 17, 2019 11:08 pm
Forum: Student Social/Study Group
Topic: Bond Angles
Replies: 6
Views: 20

Re: Bond Angles

I think we need to know relatively, but not the exact figure
by Robert Cross 1A
Sun Nov 17, 2019 10:57 pm
Forum: Trends in The Periodic Table
Topic: electron affinity
Replies: 6
Views: 12

Re: electron affinity

Electron affinity increases as you go up and to the right of the periodic table
by Robert Cross 1A
Sun Nov 17, 2019 10:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double and triple bonds
Replies: 4
Views: 15

Re: Double and triple bonds

Because the bonding pairs in the double/triple bond are sharing the same region of electron density around the same two positive poles, the pairs are forced to occupy the same region of electron density.
by Robert Cross 1A
Sun Nov 10, 2019 9:08 pm
Forum: Electronegativity
Topic: ionic character
Replies: 7
Views: 28

Re: ionic character

Lauren Sanchez 3D wrote:So if the difference in electronegativity is greater than 2, then the bond is ionic?

Yes. An ionic bond is any bond with a delta greater than 2 between the electronegativities of the two bonding elements.
by Robert Cross 1A
Sun Nov 10, 2019 9:05 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: 28

Re: Test 2

I'm going to ask in my discussion section this week but I'm fairly certain it's only on post-midterm topics.
by Robert Cross 1A
Sun Nov 10, 2019 8:58 pm
Forum: Student Social/Study Group
Topic: chem 14b + cehm14bl
Replies: 9
Views: 48

Re: chem 14b + cehm14bl

I don't know personally, but if the CHEM14 series is a part of your major requirements, it may make sense for you to ask to meet with your departmental advisor for a half-hour, as they should have a good sense of what works better for students and what doesn't. Just my $.02
by Robert Cross 1A
Sun Nov 10, 2019 8:45 pm
Forum: Lewis Structures
Topic: Electronegative
Replies: 14
Views: 32

Re: Electronegative

Electronegativity increases as you go up and to the right of the periodic table until the final Group 18 (Noble Gases). Group 18 is all the way to the right of the periodic table, except all of these have stable valence shells so their electronegativity is a much lower value than the proceeding grou...
by Robert Cross 1A
Sun Nov 10, 2019 8:42 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: Boiling point
Replies: 5
Views: 16

Re: Boiling point

The bond type doesn't necessarily contribute to boiling point, but the IMFs associated with certain bonds do. For instance, ionic salts like NaCl have strong ion-ion forces which give it its high boiling point because it requires a lot of energy in the form of heat to overcome these forces. F 2 is ...
by Robert Cross 1A
Sun Nov 03, 2019 10:48 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterms
Replies: 6
Views: 48

Re: Midterms

Good luck everyone!!!
by Robert Cross 1A
Sun Nov 03, 2019 10:47 pm
Forum: Administrative Questions and Class Announcements
Topic: study guide
Replies: 2
Views: 17

Re: study guide

I found the syllabus goes lists every topic that is covered in each unit, which might be helpful in figuring out what will be on the midterm
by Robert Cross 1A
Sun Nov 03, 2019 10:42 pm
Forum: Dipole Moments
Topic: Dipole, midterm?
Replies: 7
Views: 73

Re: Dipole, midterm?

I believe so, yes
by Robert Cross 1A
Sun Nov 03, 2019 10:41 pm
Forum: Formal Charge and Oxidation Numbers
Topic: How to know where a double bond should go?
Replies: 10
Views: 46

Re: How to know where a double bond should go?

Cl generally does not want to form double bonds with C because Cl has 7 valence electrons and just needs one additional bond to attain an octet
by Robert Cross 1A
Sun Nov 03, 2019 10:39 pm
Forum: Administrative Questions and Class Announcements
Topic: slides
Replies: 4
Views: 27

Re: slides

I looked through his website and didn't find them, but this would be a helpful review tool
by Robert Cross 1A
Sun Oct 27, 2019 9:19 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations for Exceptions
Replies: 2
Views: 15

Re: Electron Configurations for Exceptions

Yes, I believe those are correct, according to what I could find on Google
by Robert Cross 1A
Sun Oct 27, 2019 9:11 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 6
Views: 27

Re: Electronegativity

I think it's the highest electronegativity because it is at the top right of the periodic table. Halogen's are known for being very reactive because of their valence shell being one electron away from a full octet. Although Neon is further right on the table, it is a noble gas, which are nonreactive...
by Robert Cross 1A
Sun Oct 27, 2019 8:59 pm
Forum: *Black Body Radiation
Topic: What is it?
Replies: 6
Views: 60

Re: What is it?

He mentioned that in lectures although he said it is not a part of our syllabus! It is essentially bodies that absorb/emit all frequencies therefore would be essentially invisible. If you are interested in reading more into this topic, I found this simplified wikipedia article helpful in understand...
by Robert Cross 1A
Sun Oct 27, 2019 8:42 pm
Forum: Sigma & Pi Bonds
Topic: Sigma vs. Pi
Replies: 11
Views: 483

Re: Sigma vs. Pi

Simran Athwal-Dis 3A wrote:Is it true that for every double bond, there is one pi bond and for every triple bond, there are 2 pi bonds?


Yes.

Single bond = 1 sigma bond, 0 pi bonds
Double bond= 1 sigma bond, 1 pi bond
Triple bond= 1 sigma bond, 2 pi bonds
by Robert Cross 1A
Sun Oct 27, 2019 8:40 pm
Forum: Resonance Structures
Topic: Delocalization
Replies: 6
Views: 40

Re: Delocalization

It means that one or more of the electrons in a molecule's bond is not strictly limited to being shared between two atoms. I see "delocalized" as meaning it is a rogue electron (i.e. it moves between the atoms more fluidly/is not strictly limited to one bonding pair of atoms). This can be ...
by Robert Cross 1A
Sun Oct 20, 2019 8:49 pm
Forum: DeBroglie Equation
Topic: EM Radiation and DeBroglie Equation
Replies: 3
Views: 17

Re: EM Radiation and DeBroglie Equation

Callum Guo 1A wrote:i don't think theres a consensus about that, it's a weird property of light to have momentum but not mass. Heres an article that I read online: http://www.desy.de/user/projects/Physic ... _mass.html


Thank you so much for sharing this, I'd been wondering about this myself :)
by Robert Cross 1A
Sun Oct 20, 2019 8:45 pm
Forum: Photoelectric Effect
Topic: Speed of Light
Replies: 29
Views: 116

Re: Speed of Light

For the purposes of this class I think we're best off using the value given to us on Lavelle's equation sheet
by Robert Cross 1A
Sun Oct 20, 2019 8:36 pm
Forum: Photoelectric Effect
Topic: The Work Function
Replies: 15
Views: 70

Re: The Work Function

I agree with everything posted so far, but I think for clarification it should be noted that the work function of a particular metal is not dependent on the intensity of the light, but rather the individual energy of each photon. Essentially, an electron can only be emitted from the metal if the ene...
by Robert Cross 1A
Sun Oct 20, 2019 8:20 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: s-, p-, d- ,f- orbitals
Replies: 10
Views: 63

Re: s-, p-, d- ,f- orbitals

Thank you for the clarification. This is helpful :)
by Robert Cross 1A
Sun Oct 20, 2019 8:01 pm
Forum: SI Units, Unit Conversions
Topic: Calculate using kg or g?
Replies: 13
Views: 117

Re: Calculate using kg or g?

In my experience with high school chem + this course, it seems like chemistry calculations tend to be mostly done with grams. If they specifically ask you to provide an answer with another unit of mass, use that unit, but generally grams are the unit of measure used.
by Robert Cross 1A
Sun Oct 13, 2019 2:05 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: First Test Result
Replies: 5
Views: 44

Re: First Test Result

Good luck everyone!
by Robert Cross 1A
Sun Oct 13, 2019 2:04 pm
Forum: Properties of Light
Topic: EM waves
Replies: 3
Views: 14

Re: EM waves

Despite lacking mass, the release of a photon and its inherent energy results in a change in the magnetic field of the surrounding area. In QM, energy released by a photon is directly linked to a change in the magnetic field along the path of the ejected photon.
by Robert Cross 1A
Sat Oct 12, 2019 4:05 pm
Forum: Properties of Light
Topic: Constructive & Destructive
Replies: 4
Views: 37

Re: Constructive & Destructive

For destructive interference, would it be possible for the two waves to be equal to each other so that they cancel out or does the “negative” have to be smaller than the “positive” wave? Yes. A good real life example that helped me better conceptualize this can be found in how noise-cancelling head...
by Robert Cross 1A
Sat Oct 12, 2019 3:26 pm
Forum: Student Social/Study Group
Topic: Chemistry News
Replies: 61
Views: 37110

Re: Chemistry News

This article discusses how integral chemistry is to the field of art restoration

https://nuscimag.com/the-chemistry-of-art-restoration-1a034a8525c2
by Robert Cross 1A
Sat Oct 12, 2019 3:22 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Wavelength Plausibility
Replies: 29
Views: 537

Re: Wavelength Plausibility

Thank you for the clarification!
by Robert Cross 1A
Fri Oct 04, 2019 12:06 am
Forum: Limiting Reactant Calculations
Topic: Percent or theoretical yield
Replies: 14
Views: 98

Re: Percent or theoretical yield

Hello there! They are two separate things, although they are related. The percent yield is calculated by taking the mass of the actual yield (result of an experiment) divided by the mass of the theoretical yield. Then, one would multiply by 100% to express the percent yield. Basically, the percent y...
by Robert Cross 1A
Thu Oct 03, 2019 9:35 pm
Forum: SI Units, Unit Conversions
Topic: Book Access Issues
Replies: 3
Views: 59

Re: Book Access Issues

I was worried about this issue. Thank you so much for the fix :)
by Robert Cross 1A
Thu Oct 03, 2019 9:31 pm
Forum: Ideal Gases
Topic: Reading the textbook [ENDORSED]
Replies: 128
Views: 75164

Re: Reading the textbook [ENDORSED]

I find that reading the textbook can help, however normally I like to supplement reading the textbook by also looking up the concept online/reading an internet explanation/watching Khan Academy videos. I think combining resources is the most effective way to gather information on a topic, especially...
by Robert Cross 1A
Thu Oct 03, 2019 5:26 pm
Forum: Properties of Electrons
Topic: Expectations
Replies: 4
Views: 115

Re: Expectations

With regards to our fundamental and quantum understanding of electrons, I think it's important to point out a flaw that seems to have permeated throughout our education system. For me at least, I grew up being told that electrons were spherical in nature and orbited around the nucleus on set courses...
by Robert Cross 1A
Thu Oct 03, 2019 4:55 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 62
Views: 18490

Re: Final Jitters

I've always been one to take walks as a part of my studying process. I find it can be helpful in relaxing me, especially when I've been studying for hours at a time. There have been plenty of studies which have revealed the mental and physical benefits of even just a twenty minute stroll. Walking in...

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