Search found 44 matches

by rachel liu 3k
Wed Nov 20, 2019 12:08 am
Forum: Dipole Moments
Topic: dipole moments vs dipole-dipole
Replies: 2
Views: 10

Re: dipole moments vs dipole-dipole

please reply to this by quoting my question so i get a notification. thanks in advance! what is the difference between dipole moments and induced dipoles and dipole-dipole interactions? From what I understand dipole moments are permanent dipoles within a molecule, between atoms (like C-F). Induced ...
by rachel liu 3k
Wed Nov 20, 2019 12:04 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: 3F13
Replies: 3
Views: 20

Re: 3F13

For this problem, the choice showing dipole-dipole interactions between the molecules has the strongest attraction. In choice II, the partial positive H are nearest to the partial negative Cl, giving these molecules the strongest intermolecular interaction. In addition, you know that different mole...
by rachel liu 3k
Tue Nov 19, 2019 11:40 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: 3F.5 b
Replies: 2
Views: 6

Re: 3F.5 b

Hydrogens are most often bonded to carbons when drawing lewis structures. Other than this, you can figure it out by looking at the formal charge. If the 2 hydrogens are bonded to the oxygen, the oxygen would have a formal charge of 2 and the carbons at the end of the structure would have formal cha...
by rachel liu 3k
Tue Nov 19, 2019 11:39 pm
Forum: Dipole Moments
Topic: dipole moments vs dipole-dipole
Replies: 2
Views: 10

dipole moments vs dipole-dipole

please reply to this by quoting my question so i get a notification. thanks in advance! what is the difference between dipole moments and induced dipoles and dipole-dipole interactions? From what I understand dipole moments are permenant dipoles within a molecule, between atoms (like C-F). Induced ...
by rachel liu 3k
Tue Nov 19, 2019 11:26 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: 3F.5 b
Replies: 2
Views: 6

3F.5 b

please reply to this by quoting my question so i get a notification. thanks in advance! how do you know to draw C2H5OC2H5 like the diagram below and not with 2 H attached to the Oxgen? Because that would dramatically increase the melting and boiling points due to the fact that now there are two pot...
by rachel liu 3k
Fri Nov 15, 2019 5:35 pm
Forum: DeBroglie Equation
Topic: Dino Nuggets Problem 8b
Replies: 11
Views: 210

Re: Dino Nuggets Problem 8b

205150314 wrote:
rachel liu 3k wrote:
rachel liu 3k wrote:Does someone want to help me figure out what I did wrong? Thanks!

Nevermind, turns out I forgot how to do basic algebra and wasn't supposed to take out the 1/2. Thanks anyways!


this is the wrong answer though, isnt it?

Yes, it was.
by rachel liu 3k
Fri Nov 15, 2019 5:32 pm
Forum: Coordinate Covalent Bonds
Topic: coordinate covalent bond
Replies: 8
Views: 47

Re: coordinate covalent bond

What is the difference or what distinguishes a coordinate covalent bond from a regular bond? In a coordinate covalent bond both electrons come from the same atom while in a regular bond each atom provides an electron. Oh, got it! The only way you would know the type of bond (coordinate covalent vs ...
by rachel liu 3k
Fri Nov 15, 2019 5:30 pm
Forum: Sigma & Pi Bonds
Topic: Drawing
Replies: 6
Views: 21

Re: Drawing

605110118 wrote:Do we need to know how to draw the shape of different bonds?

Drawing out the 3-d molecule-based from the bonding seen in the Lewis structure helps greatly to determine the shape, so it is recommended to draw the shape of the bonds before naming it.
by rachel liu 3k
Fri Nov 15, 2019 5:28 pm
Forum: Sigma & Pi Bonds
Topic: Sigma & Pi Bonds
Replies: 4
Views: 34

Re: Sigma & Pi Bonds

Are we going to be touching on sigma and pi bonds later on (perhaps when we start the Shapes section)? Because it seems that so far we have stuck to the topics on this website pretty closely, but we've skipped this topic save for a brief mention once in lecture. Thank you! They will be covered next...
by rachel liu 3k
Fri Nov 15, 2019 5:27 pm
Forum: Sigma & Pi Bonds
Topic: hybridization
Replies: 3
Views: 38

Re: hybridization

405404782 Gabriel Rigole 4F wrote:Can someone explain hybridization and how to determine what the hybridization of a molecule is?

Just like what Eileen said, the hybridization of the molecule depends on the number of bonds around the atom in question. Dr. Lavelle will talk about it more after Test #2.
by rachel liu 3k
Wed Nov 06, 2019 9:33 am
Forum: Octet Exceptions
Topic: 2C.5
Replies: 4
Views: 38

Re: 2C.5

First, I just set up the molecule as described in the problem. From there, I added all of the 22 other electrons onto the atoms to give them octets. At first I gave Cl 6 free electrons, Oxygen 4, Nitrogen 0 and each of the oxygens 6. However, with this setup, nitrogen didn't have an octet. So, I mo...
by rachel liu 3k
Tue Nov 05, 2019 10:16 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability and Covalent Character
Replies: 5
Views: 39

Re: Polarizability and Covalent Character

Polarizability is referring to how easily displaced an atom's electrons are by neighboring atoms. In an ionic bond, ions which cause large distortions are referred to as having 'high polarizing power'. This distorts the electron density of an ion, so the electrons are being pulled into the bonding ...
by rachel liu 3k
Tue Nov 05, 2019 10:12 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability and Covalent Character
Replies: 5
Views: 39

Re: Polarizability and Covalent Character

Polarizability is referring to how easily displaced an atom's electrons are by neighboring atoms. In an ionic bond, ions which cause large distortions are referred to as having 'high polarizing power'. This distorts the electron density of an ion, so the electrons are being pulled into the bonding ...
by rachel liu 3k
Mon Nov 04, 2019 6:28 pm
Forum: DeBroglie Equation
Topic: Dino Nuggets Problem 8b
Replies: 11
Views: 210

Re: Dino Nuggets Problem 8b

8. B) A newly designed laser pointer with a certain frequency is pointed at a sodium at a sodium metal surface. An electron is ejected from the metal surface with wavelength 1.10nm. What is the frequency of the light from the laser pointer? The work function of sodium is 150.6 kJmol^1. I understand...
by rachel liu 3k
Mon Nov 04, 2019 5:12 pm
Forum: DeBroglie Equation
Topic: Dino Nuggets Problem 8b
Replies: 11
Views: 210

Re: Dino Nuggets Problem 8b

8. B) A newly designed laser pointer with a certain frequency is pointed at a sodium at a sodium metal surface. An electron is ejected from the metal surface with wavelength 1.10nm. What is the frequency of the light from the laser pointer? The work function of sodium is 150.6 kJmol^1. I understand...
by rachel liu 3k
Thu Oct 31, 2019 11:44 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability vs. Polarizing Power
Replies: 3
Views: 172

Re: Polarizability vs. Polarizing Power

Radha Patel 1A wrote:Polarizability -
- Generally for anions, are electrons that are further away from the nucleus
- more energy shells = more polarizability
Polarizing power- Generally for cations, are less electrons closer to the nucleus
- less electron shells = more polarizing power

Super helpful, thanks!!
by rachel liu 3k
Thu Oct 31, 2019 11:43 am
Forum: Formal Charge and Oxidation Numbers
Topic: FC Charge and Stability
Replies: 2
Views: 27

Re: FC Charge and Stability

Will there every be a time when the formal charge is not 0 but it is the most stable structure for the atom? I agree with Zaynab, but know that there must be a mistake in your calculation of the individual formal charges of the atoms within the molecule (even if it is not the most stable), does not...
by rachel liu 3k
Thu Oct 31, 2019 11:41 am
Forum: Electronegativity
Topic: Electronegativity vs Electron Affinity of Nitrogen
Replies: 3
Views: 12

Re: Electronegativity vs Electron Affinity of Nitrogen

I noticed that Nitrogen has a quite high electronegativity value of 3.04 but has a very low electron affinity of almost 0. I understand that Nitrogen has such a low electron affinity because adding an electron to its stable half-full 2p subshell is actually energetically unfavorable. But why does N...
by rachel liu 3k
Thu Oct 31, 2019 11:39 am
Forum: Electronegativity
Topic: Electronegativity vs Electron Affinity of Nitrogen
Replies: 3
Views: 12

Re: Electronegativity vs Electron Affinity of Nitrogen

I noticed that Nitrogen has a quite high electronegativity value of 3.04 but has a very low electron affinity of almost 0. I understand that Nitrogen has such a low electron affinity because adding an electron to its stable half-full 2p subshell is actually energetically unfavorable. But why does N...
by rachel liu 3k
Thu Oct 31, 2019 11:35 am
Forum: Dipole Moments
Topic: van der waal
Replies: 4
Views: 44

Re: van der waal

how can we tell which molecules will have a greater dipole-dipole or London force? aka what factors contribute to the strength of dipole-dipole interactions? Addressing the second part of your question, dipole-dipole interactions increase as the polarity of atoms/molecules increase. Polarity is due...
by rachel liu 3k
Thu Oct 31, 2019 11:32 am
Forum: Octet Exceptions
Topic: 2C.5
Replies: 4
Views: 38

Re: 2C.5

First, I just set up the molecule as described in the problem. From there, I added all of the 22 other electrons onto the atoms to give them octets. At first I gave Cl 6 free electrons, Oxygen 4, Nitrogen 0 and each of the oxygens 6. However, with this setup, nitrogen didn't have an octet. So, I mo...
by rachel liu 3k
Thu Oct 31, 2019 11:31 am
Forum: Sigma & Pi Bonds
Topic: Difference between Sigma & Pi
Replies: 5
Views: 52

Re: Difference between Sigma & Pi

A single bond is a sigma bond, whereas a double bond is a sigma bond and a pi bond. A sigma bond is a basic covalent bond, with the bond in line with the bonding orbitals. Only one sigma bond can exist between any two atoms. A pi bond is a covalent bond between orbitals that are perpendicular to bo...
by rachel liu 3k
Wed Oct 30, 2019 1:53 pm
Forum: Bond Lengths & Energies
Topic: dissociation energy and bond length
Replies: 1
Views: 19

Re: dissociation energy and bond length

I have a few questions regarding dissociation energy and bond length relationships 1. Do all bond types have the same dissociation energy (all C-H bonds = 412 kJ/mol?) 2. Since double bonds have an increased dissociation energy than single bonds, can we assume shorter bonds have larger dissociation...
by rachel liu 3k
Fri Oct 25, 2019 9:23 am
Forum: Bond Lengths & Energies
Topic: Review question
Replies: 3
Views: 269

Re: Review question

the answer key says c-o, but the explanation doesn't sound right. It says that since o is the smallest, but both n and c are smaller, so I really don't know. It C=O because the two ions have the greatest difference in electronegativity. Oxygen has a greater nuclear pull and will pull the shared ele...
by rachel liu 3k
Fri Oct 25, 2019 9:19 am
Forum: Octet Exceptions
Topic: Octet exception examples
Replies: 9
Views: 76

Re: Octet exception examples

Kelvin Chung 1C wrote:
Jordan Young 3E wrote:Boron also is an exception at times

Boron typically has 6 valence electrons, forming 3 covalent bonds. Right?

Yup!
by rachel liu 3k
Fri Oct 25, 2019 9:17 am
Forum: Formal Charge and Oxidation Numbers
Topic: charges and roman numerals
Replies: 5
Views: 393

Re: charges and roman numerals

On the basis of the expected charges on the monatomic ions, give the chemical formula of each of the following compounds: (a) magnesium arsenide; (b) indium(III) sulfide; (c) aluminum hydride; (d) hydrogen telluride; (e) bismuth(III) fluoride Can someone explain the roles of the roman numerals? The...
by rachel liu 3k
Fri Oct 25, 2019 9:15 am
Forum: Lewis Structures
Topic: Where to start putting dots for electrons
Replies: 10
Views: 63

Re: Where to start putting dots for electrons

When we put dots to represent valence electrons for elements, is there any rule on where (start putting dots on the left side, right side, etc.) to start drawing the dots? Like everyone else has said, there is no rule, but make sure to follow Hund's Rule. Put one valence electron in per orital firs...
by rachel liu 3k
Fri Oct 25, 2019 9:14 am
Forum: Sigma & Pi Bonds
Topic: Resonance [ENDORSED]
Replies: 3
Views: 318

Re: Resonance [ENDORSED]

i thought it dosn't have to be bonded to the same element...as long as there is variance in the bond lengths according to the lewis diagram. am i misunderstanding?
by rachel liu 3k
Fri Oct 25, 2019 9:12 am
Forum: Ionic & Covalent Bonds
Topic: Resonance
Replies: 12
Views: 76

Re: Resonance

Are we expected to draw all the resonance structures of compounds various bond lengths (no3-) when asked for a lewis structure?
by rachel liu 3k
Sat Oct 19, 2019 7:57 pm
Forum: Properties of Light
Topic: light
Replies: 5
Views: 43

light

Is the fastest thing in the world really light? like for sure for sure?
by rachel liu 3k
Sat Oct 19, 2019 7:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Easy Mnemonics for the 3 Principles!
Replies: 1
Views: 16

Easy Mnemonics for the 3 Principles!

In high school, I had to memorize all three of these rules (Pauli, Hund's and Aufbau), so I made weird mnemonics to help with it. Pauli Exclusion Principle: well this one you could remember that at PAULI Pavillion, every person has a different and unique seat, just like how no electron has the same ...
by rachel liu 3k
Sat Oct 19, 2019 7:43 pm
Forum: Properties of Electrons
Topic: Aufbau vs Hund's
Replies: 2
Views: 24

Aufbau vs Hund's

I'm a little confused on the difference between the Aufbau Principle and Hund's Rule...don't they both pretty much mean you fill the lower energy levels first and then build your way up?
by rachel liu 3k
Sat Oct 19, 2019 7:39 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: More Energy levels
Replies: 1
Views: 18

Re: More Energy levels

Why is it that when we are dealing with energy levels, as the energy levels increase, they get closer together? Does this also affect our calculations with the Bohr frequency condition or the E=-hR/n^2 formula in any way? As of now, the Rydberg formula (E=-hR/n^2), and the concepts of Balmer and Ly...
by rachel liu 3k
Sat Oct 19, 2019 7:28 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 1882

Re: Test 1 [ENDORSED]

melinak1 wrote:we can still use a scientific calculator for the exam, right?

Yes, as long as it is non-graphing!
by rachel liu 3k
Thu Oct 10, 2019 7:21 pm
Forum: *Black Body Radiation
Topic: Black Body
Replies: 4
Views: 2005

Re: Black Body

Are black bodies related to black holes?
by rachel liu 3k
Thu Oct 10, 2019 7:20 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation [ENDORSED]
Replies: 70
Views: 967

Re: Rydberg equation [ENDORSED]

In class, Professor Lavelle wrote the Rydberg equation with a negative sign on the right to show that energy was being lost. Unfortunately when I used the equation that way, my negatives got all messed up and my answer was wrong...Should I just forget that negative?
by rachel liu 3k
Thu Oct 10, 2019 6:51 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: sig figs
Replies: 20
Views: 128

Re: sig figs

Does anyone know if points will be taken off due to sig figs? My high school chem teacher was super specific on SFs.
by rachel liu 3k
Thu Oct 10, 2019 6:48 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Test Equation Sheets
Replies: 5
Views: 39

Test Equation Sheets

Is there somewhere on the website where the Equation Sheet given on the test is posted? I want to know exactly what conversions we are given so I know what to memorize...
by rachel liu 3k
Thu Oct 10, 2019 6:47 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Types of E
Replies: 3
Views: 44

Types of E

Are the variables "E" is E=hc/wavelength, and the Ek in the threshold energy equation the same?
by rachel liu 3k
Thu Oct 03, 2019 4:30 pm
Forum: Significant Figures
Topic: Sig Figs and Rounding
Replies: 4
Views: 38

Re: Sig Figs and Rounding

Hi Sophia! In my opinion, it is much better to keep as many S.F. as possible and then round at the end. In other classes that ask you to submit answers online, the websites (Pearson) get really nit-picky about getting exactly the right number and will mark answers wrong if you are even off by .01. H...
by rachel liu 3k
Mon Sep 30, 2019 5:57 pm
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 209
Views: 101146

Re: Saying Thank You to Dr. Lavelle

Dear Dr. Lavelle,
I know the class has barely started but I just want to take a moment to appreciate the little dance you do to your presentation music before class begins. It is wholesome and precious and makes my day. Thank you.
by rachel liu 3k
Mon Sep 30, 2019 5:54 pm
Forum: Balancing Chemical Reactions
Topic: Combustion Equation
Replies: 21
Views: 837

Re: Combustion Equation

Dr. Lavelle said in class today...if hydrogen, carbon, and oxygen are present in the reactants, it is most likely a combustion reaction!
by rachel liu 3k
Mon Sep 30, 2019 5:51 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Reactions
Replies: 25
Views: 207

Re: Balancing Reactions

Must the states of matter always be written in a chemical equation? (s,l,aq)
by rachel liu 3k
Mon Sep 30, 2019 5:45 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 117
Views: 1703

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

This was such a great share.. emphasizing the importance of enjoying the present, whatever that may be. I know it's very early, but for the past few weeks, I have been struggling to decide whether I should go to med school, or even stay within a STEM-related major. I feel if I don't decide soon, it ...

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