Search found 53 matches
- Sun Dec 08, 2019 8:52 pm
- Forum: Properties & Structures of Inorganic & Organic Bases
- Topic: Equilibrium sign
- Replies: 9
- Views: 910
Re: Equilibrium sign
No because reactions with strong acids and bases only go in one direction, while reactions with weak acids and bases reach equilibrium and then occur at a constant rate.
- Sun Dec 08, 2019 8:36 pm
- Forum: Lewis Acids & Bases
- Topic: What does it mean when something is strong?
- Replies: 8
- Views: 620
Re: What does it mean when something is strong?
It means they dissociate completely in solution. This correlates to being strong because it means that there are more H+ or OH- ions in the solution, making it more acidic or basic respectively.
- Sun Dec 08, 2019 8:16 pm
- Forum: Dipole Moments
- Topic: Hydrogen bonds
- Replies: 9
- Views: 619
Re: Hydrogen bonds
Lone pairs on O, F, or N can form hydrogen bonds with a H that is connected to an O, F, or N.
- Sun Dec 08, 2019 8:14 pm
- Forum: Amphoteric Compounds
- Topic: acid, base, or amphoteric
- Replies: 4
- Views: 359
Re: acid, base, or amphoteric
You can also know if a compound is amphoteric by the periodic table (refer to the diagram he showed in lecture of the diagonal stretch that tend to form amphoteric compounds).
- Sun Dec 08, 2019 8:11 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Stronger acid?
- Replies: 13
- Views: 1241
Re: Stronger acid?
HClO2, because the oxygens are more electronegative, pulling electrons away from the hydrogen. This makes the hydrogen easier to break off.
- Sun Dec 08, 2019 8:06 pm
- Forum: General Science Questions
- Topic: Grades
- Replies: 5
- Views: 655
Re: Grades
I heard the finals would be graded by Friday, but I'm not sure when they'll be put up on myucla.
- Sun Dec 08, 2019 8:03 pm
- Forum: Sigma & Pi Bonds
- Topic: How to Find Sigma Bonds and Pi Bonds
- Replies: 15
- Views: 1220
Re: How to Find Sigma Bonds and Pi Bonds
The first bond between two atoms is a sigma bond. Each following bond is a pi bond.
- Sun Dec 08, 2019 3:12 am
- Forum: Biological Examples
- Topic: EDTA
- Replies: 3
- Views: 375
Re: EDTA
I believe it is also the only hexadentate molecule we are supposed to know.
- Sun Dec 08, 2019 3:11 am
- Forum: DeBroglie Equation
- Topic: DeBroglie
- Replies: 2
- Views: 420
Re: DeBroglie
De Broglie can be used when mass or velocity is given - or both, to find the wavelength.
- Sat Dec 07, 2019 4:16 pm
- Forum: Administrative Questions and Class Announcements
- Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
- Replies: 115
- Views: 13350
Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
For number 21, why is Fe 2+? I remember him saying in the review that it was because of the nitrogen bonds, but I don't remember why.
- Fri Dec 06, 2019 11:17 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: what is a ligand?
- Replies: 7
- Views: 540
Re: what is a ligand?
A ligand is a neutral molecule or anion that donates an e- pair to form a coordinate covalent bond.
- Fri Dec 06, 2019 4:36 pm
- Forum: Administrative Questions and Class Announcements
- Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
- Replies: 115
- Views: 13350
Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
Marty Hockey wrote:For number 20 how do we know whether the expected geometry of the compound is square planar or tetrahedral?
I think that because there are no lone pairs on the Fe, it will be tetrahedral
- Fri Dec 06, 2019 2:28 pm
- Forum: Dipole Moments
- Topic: Intermolecular Forces
- Replies: 3
- Views: 254
Re: Intermolecular Forces
Yes, they are the same. They are always present because electrons in different atoms can always affect one another and create temporary dipoles.
- Wed Dec 04, 2019 8:04 pm
- Forum: DeBroglie Equation
- Topic: De Broglie Wavelength
- Replies: 23
- Views: 3452
Re: De Broglie Wavelength
You can use the de Broglie equation for other things, if they have mass. keep in mind that this means the de Broglie equation cannot be used for photons because they do not have mass.
- Wed Dec 04, 2019 1:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2 Average
- Replies: 3
- Views: 228
Re: Test 2 Average
I believe the TAs are giving them back during discussions.
- Wed Dec 04, 2019 1:14 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 2
- Views: 229
Re: Hybridization
For our purposes, I don't think we need to worry too much about double or triple bonds. They are just one region of electron density.
- Wed Dec 04, 2019 1:09 pm
- Forum: Amphoteric Compounds
- Topic: H2O
- Replies: 8
- Views: 479
Re: H2O
Yes, because it can donate an H+ (making OH-) or accept an H+ (making H3O+).
- Wed Dec 04, 2019 2:33 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: vsepr formula
- Replies: 7
- Views: 628
Re: vsepr formula
Yes, the VSEPR formula is the AXE formula.
- Tue Dec 03, 2019 8:58 pm
- Forum: Hybridization
- Topic: 2F.1
- Replies: 2
- Views: 152
Re: 2F.1
I like to think of it in terms of VSEPR - 2 bonds/electron pairs = linear, so sp hybridization; 3 bonds/EP = trigonal planar, so sp2 hybridization, and so forth. The hybridization level is equal to the number of bonds/EP.
- Tue Dec 03, 2019 8:24 am
- Forum: Lewis Acids & Bases
- Topic: Memorizing Charges of Transition Metals
- Replies: 9
- Views: 842
Re: Memorizing Charges of Transition Metals
Yes, I believe we have to memorize these and know from the names.
- Tue Dec 03, 2019 8:00 am
- Forum: Student Social/Study Group
- Topic: Practice Final
- Replies: 17
- Views: 1415
Re: Practice Final
Dr. Lavelle hasn't said anything about a practice final, so I would assume not. However, there are many review sessions and some problems available here on chem community.
- Sat Nov 30, 2019 9:37 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam Content
- Replies: 14
- Views: 809
Re: Final Exam Content
Dr. Lavelle also said that he would be finishing the syllabus material on Wednesday, and then Friday will be review I believe.
Re: Naming
I think we need to know how to do it for the final because it was covered in class and is on the outlines/homework.
- Sun Nov 24, 2019 12:01 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 Sites
- Replies: 3
- Views: 277
Re: Hydrogen Bonding Sites
Yes, they can each form a hydrogen bond. This is because they are both negatively charged, and will push away from each other but towards a partially positive hydrogen.
- Sun Nov 24, 2019 11:59 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Why are inorganic acids stronger?
- Replies: 8
- Views: 1328
Re: Why are inorganic acids stronger?
Inorganic compounds are able to lose H+ ions much more easily than organic compounds, making them stronger.
- Sun Nov 24, 2019 11:57 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw
- Replies: 23
- Views: 1055
Re: Seesaw
My TA told me that if there are lone pairs, always write less than the respective number of degrees. Thus I think you are right, see saw should be less than 90 an 120 degrees.
- Sun Nov 24, 2019 11:53 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs
- Replies: 13
- Views: 756
Re: Lone pairs
No, only on the central atom. Lone pairs on the outer atoms d not affect bond positioning with the central atom.
- Mon Nov 04, 2019 12:11 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Electron configuration
- Replies: 7
- Views: 494
Re: Electron configuration
the 4s orbital is lower in energy, so the electrons would rather be there because it is more stable.
- Mon Nov 04, 2019 12:02 am
- Forum: Einstein Equation
- Topic: Module Question
- Replies: 2
- Views: 296
Re: Module Question
c = wavelength x frequency ==> c/wavelength = frequency
E = h x frequency ==> E = h x c/wavelength ==> E x wavelength = hc ==> wavelength = hc/E
E = h x frequency ==> E = h x c/wavelength ==> E x wavelength = hc ==> wavelength = hc/E
- Sun Nov 03, 2019 11:57 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Drawing Orbitals
- Replies: 3
- Views: 251
Re: Drawing Orbitals
I think a general understanding will suffice, as long as you understand how they work.
- Sun Nov 03, 2019 11:50 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic bonds being held together
- Replies: 3
- Views: 147
Re: Ionic bonds being held together
Because one is positive and the other is negative, they are attracted to each other.
- Sun Nov 03, 2019 11:32 pm
- Forum: Photoelectric Effect
- Topic: Best way to study for this topic?
- Replies: 8
- Views: 436
Re: Best way to study for this topic?
I found that actually sitting down and reading the textbook and going through the worked out problems really helped me. I also plan on doing as many of the homework problems as possible - practice is the best way to understand it.
- Mon Oct 28, 2019 1:41 am
- Forum: Bond Lengths & Energies
- Topic: Chemical Bonds
- Replies: 4
- Views: 186
Re: Chemical Bonds
By forming a bond atoms become more stable. This is why it takes energy to break a bond - they want to remain in a more stable state and will not willingly go back to being less stable.
- Mon Oct 28, 2019 1:39 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: HW question
- Replies: 3
- Views: 163
Re: HW question
You multiply 5.00 m/s by 2 because the error is 5.00+/-5.00 m/s, so it is in either direction. This the error is the absolute value (5) times 2.
- Mon Oct 28, 2019 1:34 am
- Forum: Octet Exceptions
- Topic: expanded octet?
- Replies: 9
- Views: 476
Re: expanded octet?
Accommodating more electrons often works for the d-orbital. An element with a principle quantum number of 2 cannot be expanded because there is no 2d-orbital.
- Mon Oct 28, 2019 1:30 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: HW question 1D.11
- Replies: 5
- Views: 198
Re: HW question 1D.11
l correlates to the orbital. As you increase l, you get to another orbital. So, l=0 is s, l=1 is p and so on. I found the quantum numbers to be quite confusing but I think if you just practice them more they become easier to understand.
- Mon Oct 28, 2019 1:25 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm
- Replies: 5
- Views: 199
Midterm
Does anyone know if the midterm will be up to the quantum world or will it be what we cover next too?
- Sun Oct 20, 2019 6:44 pm
- Forum: Trends in The Periodic Table
- Topic: ionization energy
- Replies: 11
- Views: 1038
Re: ionization energy
You are right, and just as a tip to help you remember, I like to think of it as the energy required to create an ion, thus ionization energy
- Sun Oct 20, 2019 6:38 pm
- Forum: Properties of Light
- Topic: Week 3 Homework
- Replies: 9
- Views: 416
Re: Week 3 Homework
We can do the quantum homework for this week.
- Sun Oct 20, 2019 5:12 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 12
- Views: 505
Re: Midterm
Knowing Lavelle, there may be, but if not there are hours and hours of sessions on his website per week that you can go to for help.
- Sun Oct 20, 2019 5:07 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 12
- Views: 505
Re: Midterm
I think so, because that is all we'll have learned by then, but I'm sure he/our TAs will tell us in class.
- Sun Oct 20, 2019 5:02 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Spin
- Replies: 2
- Views: 112
Electron Spin
Can someone please explain why two electrons have a different spin if they are paired versus if they are parallel?
- Sun Oct 20, 2019 4:54 pm
- Forum: Properties of Electrons
- Topic: Mass of an Electron
- Replies: 14
- Views: 570
Re: Mass of an Electron
Electrons, protons, and neutrons all have a set mass that does not change from element to element. What changes the mass of elements is the number of protons and neutrons it has (electrons do not have a noticeable effect because their weight is so small that it is essentially negligible).
- Sun Oct 13, 2019 8:01 pm
- Forum: General Science Questions
- Topic: THe mole
- Replies: 5
- Views: 227
Re: THe mole
I'm not 100% sure, but I figured it was because carbon is essential to life - it is a main focus point in all forms of science and understanding it is necessary in the study of life and how the world works.
- Sun Oct 13, 2019 7:56 pm
- Forum: Photoelectric Effect
- Topic: Threshold Energy
- Replies: 4
- Views: 254
Re: Threshold Energy
Yes, I believe it does because of the structure and strength of the material.
- Sun Oct 13, 2019 7:54 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric experiment
- Replies: 3
- Views: 129
Photoelectric experiment
Can someone please explain why it was unexpected that electrons were not emitted even for high intensity light in the experiment?
- Sun Oct 13, 2019 7:43 pm
- Forum: Properties of Electrons
- Topic: Energy Level (Absorption and Emission)
- Replies: 2
- Views: 118
Re: Energy Level (Absorption and Emission)
If an electron is closer to the nucleus, it is more stable and thus releases energy (in the form of light) when going to a lower energy level. Conversely, when they are in higher energy levels, they are more unstable and have more potential energy within them.
- Sun Oct 13, 2019 7:29 pm
- Forum: Administrative Questions and Class Announcements
- Topic: test 1 grades
- Replies: 2
- Views: 122
Re: test 1 grades
I'm not sure when we'll get our tests back, but I'm pretty positive we will be getting them back. Also, it is true that we will not have a final grade until the end, and that there will be no letter assigned to individual exams - we will only be given a letter grade at the end of the quarter.
- Wed Oct 02, 2019 10:26 pm
- Forum: Limiting Reactant Calculations
- Topic: limiting reactant
- Replies: 5
- Views: 390
Re: limiting reactant
Hey! So, this isn't necessarily a limiting reactant question because there is only one reactant. It focuses more on percent yield. For this question, the chemical equation is CaCO3 (s) --> CaO (s) + CO2 (g) . We know that we used 42.73 g CaCO3, but we need to know how many moles that is. To figure t...
- Wed Oct 02, 2019 9:29 am
- Forum: Significant Figures
- Topic: Lecture on Sig Figs?
- Replies: 4
- Views: 226
Re: Lecture on Sig Figs?
My T.A. said that we should not focus too much on them, but if we want should go over them in our free time because it isn't covered in depth in lecture. Also, he said that sig figs are not usually looked for too much on tests, as long as you round reasonably. I would say that it is good to review t...
- Wed Oct 02, 2019 9:21 am
- Forum: SI Units, Unit Conversions
- Topic: Question about Showing Work
- Replies: 22
- Views: 1075
Question about Showing Work
When doing the problems in section, the T.A. was showing each step in a lot of detail. On the test, do we have to show every step or is it okay to skip some that you know already or from practice?
- Wed Oct 02, 2019 9:19 am
- Forum: Empirical & Molecular Formulas
- Topic: Clarification on the Vitamin C Example
- Replies: 6
- Views: 265
Re: Clarification on the Vitamin C Example
I think the small amount 'lost' is due to rounding - if we went out further in the decimal places then we would likely have gotten a value slightly closer to 8.000. Additionally, in real life we will nearly always be slightly off of the theoretical value, due to things like solution sticking to the ...
- Wed Oct 02, 2019 9:15 am
- Forum: Significant Figures
- Topic: General Rules to Help with Sig Figs
- Replies: 18
- Views: 1060
Re: General Rules to Help with Sig Figs
My T.A. said that we don't need to worry about sig figs too much, and that we should focus more on always having units.