Search found 50 matches
- Sat Dec 07, 2019 11:58 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radii
- Replies: 11
- Views: 748
Re: Atomic Radii
It's very useful for determining bond strength and length! I don't think they can ask us to calculate it because it would need to be experimentally confirmed.
- Sat Dec 07, 2019 11:49 pm
- Forum: *Shrodinger Equation
- Topic: schrodingers equation
- Replies: 8
- Views: 667
Re: schrodingers equation
My TA said that we should know the concept behind the equation, but that we won't be asked to solve anything with it.
- Sat Dec 07, 2019 11:47 pm
- Forum: Properties of Electrons
- Topic: Mass of an electron
- Replies: 9
- Views: 778
Re: Mass of an electron
It will be given on the reference sheet! It's listed as "constants and equations sheet" on his website if you want to practice with it before the exam.
- Sat Dec 07, 2019 11:45 pm
- Forum: Empirical & Molecular Formulas
- Topic: Rounding
- Replies: 6
- Views: 641
Re: Rounding
I would only round if it was very close to a whole number. I think anything above 0.9 is safe, but anything less should be multiplied to get whole numbers across the board.
- Sat Dec 07, 2019 11:43 pm
- Forum: General Science Questions
- Topic: Curve
- Replies: 9
- Views: 952
Re: Curve
In his syllabus, Lavelle says that he sets a C- at a 50% in the class (raw score). He doesn't make the scale for what qualifies as an A or B until after the final exams are graded. Each exam isn't curved, but the entire class is. Hope this helps :)
- Sun Dec 01, 2019 7:52 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: PH
- Replies: 5
- Views: 414
Re: PH
pH = -log[H3O+]
pH is a measure of the amount of hydrogen ions in the solution! A pH of 1 to 6.9 is acidic, 7 is neutral, and 7.1 to 14 is basic.
pH is a measure of the amount of hydrogen ions in the solution! A pH of 1 to 6.9 is acidic, 7 is neutral, and 7.1 to 14 is basic.
- Sun Dec 01, 2019 7:48 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Studying for final exam
- Replies: 8
- Views: 649
Re: Studying for final exam
In general there is a lot of material that we need to memorize for the final from the last few weeks, so I think that flash cards are going to be very helpful. I'm also going to be doing the practice problems, and attending as many review sessions as possible. Good luck on the final!
- Sun Dec 01, 2019 7:43 pm
- Forum: Bronsted Acids & Bases
- Topic: Conjugate acids and bases
- Replies: 5
- Views: 488
Re: Conjugate acids and bases
For a conjugate acid, write the formula for the base but add a proton with an H+, and for the conjugate base of an acid, take away an H+.
Example: HCO3– ion.
Conjugate acid: H2CO3,
Conjugate base: CO32–
Example: HCO3– ion.
Conjugate acid: H2CO3,
Conjugate base: CO32–
- Sun Dec 01, 2019 7:38 pm
- Forum: General Science Questions
- Topic: Week 10 Classes
- Replies: 7
- Views: 521
Re: Week 10 Classes
Friday is definitely a review day!
- Sun Dec 01, 2019 7:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Points
- Replies: 11
- Views: 771
Re: Points
My TA said that we should try to make the 5 posts per week, but was very vague on the way that they were being graded. If you have 50 points by the end of the quarter, you should be okay!
- Sun Nov 24, 2019 3:30 pm
- Forum: Biological Examples
- Topic: Heme complex
- Replies: 8
- Views: 682
Re: Heme complex
On a test we would most likely have to identity which ligands were bound to which transition metal, and identify if this had any biological significance based on what we know about it's properties (given the charge and any background info the question gives us on where in the body this works or what...
- Sun Nov 24, 2019 3:26 pm
- Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
- Topic: Hydrogen Bonding/Pi bonds
- Replies: 11
- Views: 1634
Re: Hydrogen Bonding/Pi bonds
Pi bonds are also only present in double and triple bonds, since it needs an unhybridized P orbital, while hydrogen bonds are technically sigma bonds since they're only single bonds.
- Sun Nov 24, 2019 3:21 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: AXE formula
- Replies: 32
- Views: 12254
Re: AXE formula
Yes, you can determine the molecular shape from the formula. The subscript off of Xn tells you how many things are bonded to the central atom, and the subscript off of Em tells you how many lone pairs there are on the central atom. With this information, we can figure out the molecular shape. I sugg...
- Sun Nov 24, 2019 3:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent Shape
- Replies: 31
- Views: 2997
Re: Bent Shape
One or two, depending on it's VSEPR formula. It can be either AX2E or AX2E2.
- Sun Nov 24, 2019 3:14 pm
- Forum: Naming
- Topic: Homework problems Week 9
- Replies: 4
- Views: 278
Re: Homework problems Week 9
Technically, the university doesn't officially cancel any class that is before 3pm on Wednesday. My TA said that he would make this week's discussion optional, and collect week 9 and 10 homework together during week 10. I would ask your TA to be sure if you need to go on Wednesday!
- Fri Nov 15, 2019 11:06 am
- Forum: Resonance Structures
- Topic: Orbitals
- Replies: 4
- Views: 379
Re: Orbitals
In the terms of this class, it's an electron that isn't associated with a bond or single atom, so it's free to move about in the atom's space. It isn't "localized" or held to a specific region, like it would most likely be if it were in a bond.
- Fri Nov 15, 2019 11:03 am
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Will polarizability/polarizing power be on test 2?
- Replies: 3
- Views: 305
Re: Will polarizability/polarizing power be on test 2?
Because it wasn't on the midterm, I believe that it will show up on test 2.
- Fri Nov 15, 2019 10:59 am
- Forum: Bond Lengths & Energies
- Topic: Bond lengths
- Replies: 8
- Views: 417
Re: Bond lengths
I think we need to know it concept-wise, like which are stronger and shorter and which are longer and weaker.
- Fri Nov 15, 2019 10:57 am
- Forum: Sigma & Pi Bonds
- Topic: Drawing
- Replies: 6
- Views: 340
Re: Drawing
I think we're responsible for knowing how to identify the shape and the bond angles.
- Fri Nov 15, 2019 10:56 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2
- Replies: 11
- Views: 552
Re: Test 2
I'm using lots of flashcards to memorize the specific shapes and bond angles. Do you think that this will be the same level of difficulty as test 1 or will it be closer to what we had for the midterm?
- Fri Nov 08, 2019 10:29 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: D Subshell
- Replies: 7
- Views: 750
Re: D Subshell
The D subshell can hold 10 electrons because it has 5 orbitals, each holding a max of 2 electrons.
- Fri Nov 08, 2019 10:27 am
- Forum: Properties of Light
- Topic: Frequency vs. Velocity
- Replies: 8
- Views: 866
Re: Frequency vs. Velocity
The velocity of light is equal to the constant c, while we can find the frequency of light given it's wavelength.
- Fri Nov 08, 2019 10:26 am
- Forum: SI Units, Unit Conversions
- Topic: Photons
- Replies: 3
- Views: 345
Re: Photons
eV is another unit that can measure energy, with 1 ev=1.602×10−19 J. We usually convert them to Joules so that we can solve the problem using SI units.
- Fri Nov 08, 2019 10:24 am
- Forum: Balancing Chemical Reactions
- Topic: Balancing This Equation
- Replies: 11
- Views: 1168
Re: Balancing This Equation
Combustion reactions always indicate that the reactant will be burned in O2, and the products at minimum are CO2 and H2O, but there may be others, depending on what exactly was burned in oxygen.
- Fri Nov 08, 2019 10:22 am
- Forum: General Science Questions
- Topic: Test 2
- Replies: 20
- Views: 853
Re: Test 2
It's only covering topics after the first midterm!
- Fri Nov 01, 2019 10:47 am
- Forum: Significant Figures
- Topic: Sig Figs on Tests
- Replies: 24
- Views: 2250
Re: Sig Figs on Tests
Always use the lowest number of sig figs stated in the problem! I know that most TAs are lenient on sig figs, but they may grade harsher for the midterm.
- Fri Nov 01, 2019 10:46 am
- Forum: Bond Lengths & Energies
- Topic: Lattice Energy
- Replies: 9
- Views: 460
Re: Lattice Energy
Lattice energy is the energy stored in the bonds of a crystalline solid ionic compound
- Fri Nov 01, 2019 10:42 am
- Forum: Resonance Structures
- Topic: Delocalization vs. Resonance
- Replies: 8
- Views: 2998
Re: Delocalization vs. Resonance
Resonance represents the tendency of electrons to move within a molecule, so we draw out all possible locations. Decolonization represents the tendency of atoms to delocalize, or spread out.
- Fri Nov 01, 2019 10:41 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge equation
- Replies: 9
- Views: 257
Re: Formal Charge equation
One way to simplify the equation that Lavelle gave us in class is to take the total number of valence electrons in your compound, and then subtract the number of 'sticks' (or bonds) and subtract the number of 'dots' (lone electrons). For me, this saves time and I always get the same formal charge th...
- Fri Nov 01, 2019 10:36 am
- Forum: Administrative Questions and Class Announcements
- Topic: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
- Replies: 52
- Views: 6809
Re: DINO NUGGETS Review Session! Download Problems HERE [ENDORSED]
How will the difficulty of these problems compare to the difficulty of the midterm?
- Fri Oct 25, 2019 11:04 pm
- Forum: Ionic & Covalent Bonds
- Topic: Meaning of Brackets
- Replies: 7
- Views: 371
Re: Meaning of Brackets
We do this as an easy way to shorten the written electron configuration. Inside of the brackets is the closest noble gas from the row above, since their electron configuration doesn't change, and then next to it we write out the next electrons that our element has above the noble gas.
- Fri Oct 25, 2019 11:01 pm
- Forum: Electronegativity
- Topic: Nonmetals?
- Replies: 6
- Views: 753
Re: Nonmetals?
Generally, nonmetals are more electronegative because they are closer to a full outershell/ octet, so they have a stronger pull on electrons and are far more likely to gain electrons.
- Fri Oct 25, 2019 10:58 pm
- Forum: Octet Exceptions
- Topic: Resonance structures
- Replies: 5
- Views: 282
Re: Resonance structures
I think it depends on what the problem asks for, but in general always indicate resonance if there is any and explain why you included the structure that you did (assuming you included one in place of all of them).
- Fri Oct 25, 2019 10:56 pm
- Forum: Resonance Structures
- Topic: Lewis Structure vs. Resonance Structure
- Replies: 4
- Views: 675
Re: Lewis Structure vs. Resonance Structure
Resonance structures show us multiple forms of a molecule, where the chemical connectivity is the same but the electrons are distributed differently around the structure.
- Fri Oct 25, 2019 10:53 pm
- Forum: Lewis Structures
- Topic: Denoting charge on ions
- Replies: 2
- Views: 116
Re: Denoting charge on ions
My understanding of it is that this process is going to make it easier as we move on to more complex problems, like how we write out every single step in math when we are learning a new topic or how to use a new equation.
- Fri Oct 18, 2019 10:27 am
- Forum: Photoelectric Effect
- Topic: Spectrum of light
- Replies: 6
- Views: 324
Re: Spectrum of light
A helpful mnemonic device to remember the order is "I saw my Grandma's X-rated Underpants Visible In My Room" (Gamma, x-ray, uv, visible, infrared, micro, radio). It's a little wacky, but it works!
- Fri Oct 18, 2019 10:21 am
- Forum: Balancing Chemical Reactions
- Topic: Determining the state of matter
- Replies: 4
- Views: 432
Re: Determining the state of matter
I don't think we are required to know unless it is specifically stated or indicated in the problem given. The question might give the compound's state explicitly, or it may tell us that it has a very high boiling temp, so that we know it may be liquid at room temperature. Some states of compounds we...
- Fri Oct 18, 2019 10:15 am
- Forum: Molarity, Solutions, Dilutions
- Topic: What is Molarity?
- Replies: 11
- Views: 1052
Re: What is Molarity?
Molarity is a measure of the concentration of a solution, is given in moles of solute per liter of solvent, and usually is denoted by "M".
- Fri Oct 18, 2019 10:13 am
- Forum: Ionic & Covalent Bonds
- Topic: Bonds
- Replies: 4
- Views: 424
Re: Bonds
Most ionic bonds are formed between a metal and a nonmetal element, when the electron is given/not shared. Covalent bonds are usually formed between two nonmetal elements, and they share the electrons.
- Fri Oct 18, 2019 10:11 am
- Forum: SI Units, Unit Conversions
- Topic: Calculate using kg or g?
- Replies: 13
- Views: 898
Re: Calculate using kg or g?
I think that a good rule of thumb is to give the answer in grams, unless the question specifies kilograms. We usually need to convert to grams to use the molar mass conversions, so at least we're already there!
- Fri Oct 11, 2019 10:35 am
- Forum: Properties of Light
- Topic: Speed of light
- Replies: 9
- Views: 314
Re: Speed of light
If the question specifically states that it's not in a vacuum, then we can calculate the speed based on the index of the material that it's travelling through. However I think that we'll always be asked about light in a vacuum for the scope of this class? We should ask the TAs for clarification.
- Fri Oct 11, 2019 10:31 am
- Forum: Administrative Questions and Class Announcements
- Topic: Week 2 Homework Problems [ENDORSED]
- Replies: 67
- Views: 7883
Re: Week 2 Homework Problems [ENDORSED]
For week 3 we should only be submitting problems from the quantum section. We were allowed to submit fundamentals problems for week 2 because so many students were still preparing for the test, and he didn't want us to have to confuse ourselves with new material before it.
- Fri Oct 11, 2019 10:26 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Theoretical vs. Actual Yield
- Replies: 38
- Views: 14103
Re: Theoretical vs. Actual Yield
We calculate theoretical yield based on the limiting reagent. We use however many moles of the LR and the molar ration of the balanced equation to determine how much product we could make under perfect conditions. Actual yield needs to be given in the question, since we don't know it without doing t...
- Fri Oct 11, 2019 10:18 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Test 1 [ENDORSED]
- Replies: 107
- Views: 22815
Re: Test 1 [ENDORSED]
We don't need a blue book or a scantron, and a fact sheet with equations and things like Avogadro's number will be provided. Don't forget your scientific calculator! Good luck everyone!
- Fri Oct 11, 2019 10:15 am
- Forum: Administrative Questions and Class Announcements
- Topic: Weekly Posts
- Replies: 4
- Views: 250
Re: Weekly Posts
I doubt that our posts carry over. I think the objective is for us to be engaging with our class each week, but we should ask the TAs for clarification.
- Fri Oct 04, 2019 9:17 am
- Forum: Empirical & Molecular Formulas
- Topic: Test Materials
- Replies: 13
- Views: 740
Re: Test Materials
Don't forget to bring your bruincard to major exams! Some classes/proctors require it to prove that you are indeed the student who is supposed to be taking the exam that you're turning in.
- Fri Oct 04, 2019 9:12 am
- Forum: Empirical & Molecular Formulas
- Topic: 100 gram Method?
- Replies: 9
- Views: 1170
Re: 100 gram Method?
Just be careful and read the problem thoroughly! This trick only works if you are given mass percentage composition but aren't given any specific mass of your sample.
- Fri Oct 04, 2019 9:08 am
- Forum: Empirical & Molecular Formulas
- Topic: What decimal place to round to when taking masses from the Periodic Table?
- Replies: 19
- Views: 2986
Re: What decimal place to round to when taking masses from the Periodic Table?
I use all of the decimal places given usually, but I stop at 3 if pressed for time. I think using sig figs at the end is the best way to ensure accuracy in your calculations. But, on the exam we all should be given the same table so any problems from slight differences in masses we see on the homewo...
- Fri Oct 04, 2019 9:04 am
- Forum: Empirical & Molecular Formulas
- Topic: Tips for Finding Which Number to Multiply a Decimal By to Get a Whole Number
- Replies: 10
- Views: 1196
Re: Tips for Finding Which Number to Multiply a Decimal By to Get a Whole Number
With odd decimals, I usually go back to check my work just to make sure that it's all correct before I begin sorting out the odd decimal. Other posters have mentioned visualizing it as a fraction, and I think that that's a great way to go. For instance, if you get 0.636, that's 7/11. To quickly get ...
- Fri Oct 04, 2019 8:55 am
- Forum: Empirical & Molecular Formulas
- Topic: When should one start rounding in a problem?
- Replies: 11
- Views: 592
Re: When should one start rounding in a problem?
It's a good rule of thumb to always round at the end of solving. That way, your numbers are as precise as possible and you don't lose anything important in the actual calculation portion.