Search found 55 matches
- Sat Dec 07, 2019 8:15 pm
- Forum: Resonance Structures
- Topic: when there is resonance
- Replies: 5
- Views: 478
Re: when there is resonance
No, you need at least 3 atoms to have resonance because the double bond must be switched with one that has a single bond.
- Sat Dec 07, 2019 7:39 pm
- Forum: Student Social/Study Group
- Topic: Grades
- Replies: 14
- Views: 1026
Re: Grades
I am a bit confused by the grading but it sounds like the whole class is rounding comparative to everyone else's total score out of 500.
- Sat Dec 07, 2019 7:37 pm
- Forum: Lewis Structures
- Topic: Lewis for carbon monoxide
- Replies: 3
- Views: 1279
Re: Lewis for carbon monoxide
With a double bond and one lone pair on each atom, you do not form a full octet because there's only 6 electrons on carbon and oxygen. In order to get full octets and an overall neutral charge you must use the triple bond and a lone pair on each.
- Thu Dec 05, 2019 4:09 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Shape of Coordination Compounds
- Replies: 1
- Views: 179
Shape of Coordination Compounds
How many coordination compound shapes do we need to know?
Re: naming
I am not sure exactly how much naming will be on the final but definitely memorize the worksheet he gave us.
- Thu Dec 05, 2019 2:50 pm
- Forum: Biological Examples
- Topic: Biological questions on the final
- Replies: 5
- Views: 503
Re: Biological questions on the final
I think all you need to know is hemoglobin, myoglobin and cisplatin.
- Sat Nov 30, 2019 5:05 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Drawing sigma & Pi bonds
- Replies: 7
- Views: 661
Re: Drawing sigma & Pi bonds
the most important thing is knowing where sigma and pi bonds are located and their orientation; sigma bonds are end to end while pi bonds are side by side
- Fri Nov 29, 2019 5:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Studying for the Final [ENDORSED]
- Replies: 11
- Views: 786
Re: Studying for the Final [ENDORSED]
Personally, I like videos. I would also focus on the major concepts in addition to just doing problems.
- Fri Nov 29, 2019 3:43 pm
- Forum: Student Social/Study Group
- Topic: Final Review Sessions
- Replies: 7
- Views: 593
Re: Final Review Sessions
He doesn't have anything up yet on the website about review sessions but I'm sure he'll mention it on Monday. There's also the workshops and step up sessions for review.
- Fri Nov 29, 2019 3:40 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: pH vs. pOH
- Replies: 17
- Views: 2547
Re: pH vs. pOH
pH is a measure of acidity, specifically it measures the H+ ions. pOH is a measure of basicity, specifically the OH ions. Their respective values are inverse of each other. For example, ph of 0 is a pOH of 14.
- Fri Nov 29, 2019 3:36 pm
- Forum: Student Social/Study Group
- Topic: Preparing for the final
- Replies: 25
- Views: 1312
Re: Preparing for the final
The same thing happened to me as well. I think the best thing to do is to do textbook problems but also attend as many review sessions as possible. From what I heard, the final might be more conceptually focused so understanding certain principles is imperative.
- Sun Nov 24, 2019 12:49 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 415220
Re: Final Jitters
I get test anxiety as well. I recommend not studying at all the day of the final. As terrifying as it sounds it will help you heeled when it comes time for the test. Your brain won’t be overloaded with chem info and it personally helps me feel confident. I try to listen to the same music that I stud...
- Sun Nov 24, 2019 12:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs
- Replies: 13
- Views: 767
Re: Lone pairs
the only lone pairs that matter are the ones on the central atom, for example it makes the difference between linear and bent
- Sun Nov 24, 2019 12:41 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AXE Format
- Replies: 34
- Views: 1299
Re: AXE Format
Writing just E is fine.
- Sun Nov 24, 2019 12:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Non-polar molecules with different non-central atoms
- Replies: 3
- Views: 234
Re: Non-polar molecules with different non-central atoms
It depends where the two atoms are placed. If they same atoms aren’t opposite of each other their dipole moments won’t cancel out thereby making it polar.
- Wed Nov 20, 2019 8:14 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.13 part a
- Replies: 3
- Views: 264
2E.13 part a
For part A in question 13 of 2E, I3- has a bond angle of 180 degrees even though it has 3 lone pairs on it. Why isn't its bond angle less than 180 degrees?
- Sun Nov 17, 2019 11:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bonds in VSEPR
- Replies: 11
- Views: 661
Re: Bonds in VSEPR
Double and Triple bonds are accounted for as single bonds. So regardless of the number of bonds, it only counts as one region of electron density.
- Sun Nov 17, 2019 11:31 pm
- Forum: Ionic & Covalent Bonds
- Topic: Study Group
- Replies: 8
- Views: 526
Re: Study Group
I would love to join! I really need to study before this test.
- Sun Nov 17, 2019 11:30 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion Strength
- Replies: 5
- Views: 412
Re: Repulsion Strength
Lone pairs have the greatest repulsion because they are closer together. Lone bonding is the next strongest because it is the next closest. Bonding-bonding pairs are the weakest because the electrons are more spread apart since each atom takes an electron within its cloud.
- Sun Nov 17, 2019 11:19 pm
- Forum: Coordinate Covalent Bonds
- Topic: coordinate covalent bond
- Replies: 9
- Views: 690
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 ...
- Sun Nov 17, 2019 11:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Effect of electronegativity difference on bond angles
- Replies: 3
- Views: 495
Re: Effect of electronegativity difference on bond angles
Yes, the more electronegative fluorine atom pulls more of the electron cloud decreasing the repulsion between the C-H bond. But I think it increases the F-C-H bond angle because the fluorine is pulled out "further" so the H-C-H bond angle will decrease as a result of the pull. For the test...
- Fri Nov 15, 2019 9:55 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: 3F problem 3
- Replies: 3
- Views: 300
Re: 3F problem 3
Dipole-dipole moments will exist for b,c, and d. CH4 and CCl4 are completely uniform since the atoms around the central atom are the same. Because of this there is not dipole pull because there’s an even amount of electronegativity around carbon. In the case of CH3Cl, CH2Cl2, and CHCl3 there’s diffe...
- Fri Nov 15, 2019 9:51 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: Does dipole-dipole force only exist among polar molecules?
- Replies: 9
- Views: 1338
- Fri Nov 15, 2019 9:51 am
- Forum: General Science Questions
- Topic: Test 2
- Replies: 4
- Views: 306
Re: Test 2
Everything from 2D on so chemical forces/bonds and structures (Lewis and vsepr)so basically from the midterm to the lecture today
- Wed Nov 13, 2019 8:41 pm
- Forum: Coordinate Covalent Bonds
- Topic: coordinate covalent bond
- Replies: 9
- Views: 690
Re: coordinate covalent bond
Ruby Richter 4G wrote: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.
- Wed Nov 13, 2019 8:33 pm
- Forum: Coordinate Covalent Bonds
- Topic: coordinate covalent bond
- Replies: 9
- Views: 690
Re: coordinate covalent bond
Water is an example of a coordinate covalent bond, oxygen provides both electrons to the hydrogens.
- Sat Nov 09, 2019 6:57 pm
- Forum: Electronegativity
- Topic: Polar Molecules
- Replies: 4
- Views: 327
Re: Polar Molecules
If the electronegativity difference is greater than 2 then it is polar. It could be either ionic polar or covalent polar.
- Sat Nov 09, 2019 6:55 pm
- Forum: Dipole Moments
- Topic: calculating dipole moments
- Replies: 1
- Views: 102
Re: calculating dipole moments
Dipole moments are calculated by multiplying the charge by the distance between the atoms.
- Sat Nov 09, 2019 6:52 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: Hydrogen Bonding
- Replies: 3
- Views: 122
Re: Hydrogen Bonding
It bonds to highly electronegative elements while being not as negative. As a result, there is an attraction between a very weak element and a very strong one that tremendously pulls on hydrogen’s electron. Hydrogen can be considered the weakest element because it only had one electron to exert forc...
- Sat Nov 02, 2019 4:58 pm
- Forum: Lewis Structures
- Topic: Resonance Hybrids
- Replies: 3
- Views: 176
Re: Resonance Hybrids
Resonance structures are the different variations of the double bond. A resonance hybrid is the blend of all three resonance structures. It is how the molecules are represented in real life because it evenly distributes the double bond. This is known as the delocalization of electrons.
- Sat Nov 02, 2019 4:55 pm
- Forum: Ionic & Covalent Bonds
- Topic: "Primarily Ionic" Bonds (HW 2D.3)
- Replies: 2
- Views: 136
Re: "Primarily Ionic" Bonds (HW 2D.3)
There is still an electronegative difference between Be and Br but it isn't as great as the one between Ba and Br. I believe that's why you would regard BaBr2 as primarily ionic
- Sat Nov 02, 2019 4:45 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: What d to include when "counting valence electrons including d electrons"
- Replies: 1
- Views: 140
Re: What d to include when "counting valence electrons including d electrons"
Yes, Sb's 4d orbital was full and would then not be considered as valence electrons
- Sat Nov 02, 2019 4:43 pm
- Forum: Octet Exceptions
- Topic: Octet Exceptions
- Replies: 3
- Views: 246
Re: Octet Exceptions
It has to be from period 3 onward
- Sat Nov 02, 2019 4:42 pm
- Forum: Lewis Structures
- Topic: drawing lewis structures
- Replies: 5
- Views: 218
Re: drawing lewis structures
Br has an expanded octet
- Sun Oct 27, 2019 1:21 am
- Forum: Properties of Light
- Topic: Light vs. Particles
- Replies: 2
- Views: 184
Re: Light vs. Particles
Particles use de Broglie's equation (lambda=h/mv) because they have mass. Light uses E=hc/lambda because the equation features the speed of light and does not include mass since light does not have measurable mass.
- Sun Oct 27, 2019 1:16 am
- Forum: SI Units, Unit Conversions
- Topic: Midterm
- Replies: 6
- Views: 368
Re: Midterm
I believe it will have everything up to chemical bonds on there.
- Sun Oct 27, 2019 1:14 am
- Forum: Einstein Equation
- Topic: Total Energy of Light
- Replies: 2
- Views: 244
Re: Total Energy of Light
technically E=hf=hc/lambda calculates total energy of a photon
- Sun Oct 27, 2019 1:11 am
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 4
- Views: 353
Re: Resonance
A substance has resonance when the molecule requires a double bond that can be shifted to another single bond. As long as there's at least three elements and a required double bond, a resonance structure can be made.
- Thu Oct 24, 2019 9:12 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Order of electron configuration
- Replies: 6
- Views: 270
Re: Order of electron configuration
Although 4s is filled first, you write 3D first because it still occupies a slighter lower energy level.
- Sat Oct 19, 2019 5:54 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron configuration for Ag
- Replies: 2
- Views: 211
Re: Electron configuration for Ag
the 5s1 goes last
- Sat Oct 19, 2019 5:51 pm
- Forum: General Science Questions
- Topic: Tutoring
- Replies: 6
- Views: 409
Re: Tutoring
The tutoring offered on the website are all group sessions. Maybe you could contact your TA for one-on-one sessions but I would say that showing up to their office hours works best because you can ask them all the questions you have.
- Sat Oct 19, 2019 5:46 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Determining # of Subshells in an Orbital
- Replies: 3
- Views: 265
Re: Determining # of Subshells in an Orbital
As far as I know it is just something you memorize.
- Mon Oct 14, 2019 3:57 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Indeterminacy Equation
- Replies: 3
- Views: 186
Re: Indeterminacy Equation
The uncertainty is the range that the velocity would fall into. So in this case, it would fall between 0 and 10 m/s.
- Mon Oct 14, 2019 3:55 pm
- Forum: *Shrodinger Equation
- Topic: Midterm
- Replies: 14
- Views: 1110
Re: Midterm
The midterm is November 6.
- Wed Oct 09, 2019 8:25 am
- Forum: Photoelectric Effect
- Topic: Photon [ENDORSED]
- Replies: 6
- Views: 317
Re: Photon [ENDORSED]
Photons are essentially packets of energy. The photoelectric effect basically states that a certain amount of energy is required to emit an electron from a metal (work function). If the photon's energy equals or exceeds the work function then the photon will transfer it's energy to the electron so t...
- Wed Oct 09, 2019 8:19 am
- Forum: SI Units, Unit Conversions
- Topic: How to express answers
- Replies: 13
- Views: 525
Re: How to express answers
He hasn't said how he wants them expressed. I would go with scientific notation with the base units (g, mole, L). Just always make sure your sig figs are correct.
- Wed Oct 09, 2019 8:12 am
- Forum: Significant Figures
- Topic: Are we allowed to round when showing work?
- Replies: 7
- Views: 533
Re: Are we allowed to round when showing work?
I believe so. I usually do the same thing but on the test I'm going to show all my unrounded answers just in case. The most important thing is that you're not rounding before the final answer.
- Wed Oct 09, 2019 8:11 am
- Forum: SI Units, Unit Conversions
- Topic: Conversion
- Replies: 3
- Views: 246
Re: Conversion
Yes millimol means 10^-3 moles. When converting from moles to grams you multiply the moles by the molar mass.
Moles * grams/mole = grams
Moles * grams/mole = grams
- Wed Oct 02, 2019 7:21 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Dilution Calculations
- Replies: 3
- Views: 146
Re: G.23
I believe it's just extra information that isn't necessary to finding the solution to the problem.
- Wed Oct 02, 2019 7:17 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting reactant
- Replies: 4
- Views: 251
Re: Limiting reactant
When you compare the moles of the reactants check to see which compound is in excess. For example is A:B is 1:2 in the balanced equation. If the moles calculated for A is 1 and the moles calculated for B is 3 then B is in excess meaning that A is the limiting reactant. A doesn't have enough of itsel...
- Wed Oct 02, 2019 7:11 pm
- Forum: Empirical & Molecular Formulas
- Topic: Homework question M.17
- Replies: 2
- Views: 271
Re: Homework question M.17
The 1.0 comes form the hydrogen in HA and the 17.0 comes from the OH (16 g + 1 g) in XOH.
- Wed Oct 02, 2019 7:07 pm
- Forum: SI Units, Unit Conversions
- Topic: Homework 2
- Replies: 7
- Views: 349
Re: Homework 2
I'm not 100% sure but believe it would be the first discussion of next week since Week 2 homework needs to be turned in during week 2.
- Wed Oct 02, 2019 7:04 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity
- Replies: 4
- Views: 133
Re: Molarity
First you need to subtract the mass of (OH)x2 from the molar mass of the metal. When subtracting you find out the unknown metal is calcium. 74.10 - 34.02 = 40.08 Next, add the mass of Sulfur to the remaining amount. This is adding the masses of Calcium and Sulfur to create calcium sulfide. 40.08 + 3...
- Wed Oct 02, 2019 6:58 pm
- Forum: Empirical & Molecular Formulas
- Topic: H25 Fundamental Question
- Replies: 3
- Views: 283
Re: H25 Fundamental Question
Phosphorus has 5 valence electrons. The numbers in parenthesis refer to the oxidation states. Phosphorus V is when the element is in the +5 oxidation state meaning that it has removed all its valence electrons. Phosphorus iii means 2 electrons have been removed leaving a +3 charge.
- Wed Oct 02, 2019 6:42 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity
- Replies: 9
- Views: 393
Re: Molarity
Knowing the molarity can also help you find the moles of a compound given that you know the volume and vice versa.