CHEMISTRY COMMUNITY

victoriatanaka1C

We know NH3 is a base, but assuming we didn't know this, how would we know that it would accept protons rather than lose them? Is it because it wants to form NH4, which is a strong acid?

And what are good acids/bases to have memorized? I didn't write down what Dr. Lavelle suggest we know...

victoriatanaka1C

Is ligand just a special name for the thing bonded to the central atom? Like, what really is their significance?

victoriatanaka1C

Yes! Our textbook says:

Acid ----donates H+----> conjugate base

Base ----accepts H+----> conjugate acid

victoriatanaka1C

And just to clarify, the elements that can break the octet rule are H, He, Li, Be, Column 13 and Row 3 and below?

victoriatanaka1C

Will we have to know the differences between ligands? Like in class Dr. Lavelle drew cis-platinum and trans-platinum. Do we have to know keywords like cis and trans in order to draw the right version?

victoriatanaka1C

In the syllabus, for Chapter 4, it says we need to know "hybridization (sp, sp2 sp3, dsp3, d2sp3) and apply this bonding model to inorganic, organic, and biological compounds (molecules, cations, and anions))." I'm just going to try to memorize, unless anyone else has any tips for figuring...

victoriatanaka1C

I just looked at this link and it seems to cover everything! https://socratic.org/questions/how-do-y ... a-compound

I too am curious about if we'll have to have this memorized for the final...

victoriatanaka1C

Kind of...I think a formal charge of 0 means electrons are equally shared in covalent bonds. I'm not sure if that's the main purpose of formal charge though!

victoriatanaka1C

Thanks so so much! My email is victoriatanaka@g.ucla.edu

victoriatanaka1C

Hi! I wasn't able to attend lecture last Wednesday or Friday because of health reasons. Would any of you be willing to send me the notes for these days? Thanks!

victoriatanaka1C

The central atom can have an expanded octet if it appears in Group 3 or below. Their d-orbitals allow for bonding beyond 8 e-. There are also other exceptions to the octect rule, like Group 13 elements, H, He, Li, and Be. The octet rule is a guideline, not a hard fast rule!

victoriatanaka1C

I think it's because O is slightly more electronegative, so it wants to hog that extra e- to get an octet.

victoriatanaka1C

For 3.59a you're supposed to draw the Lewis structure for ClO and in the answer key it says the unpaired electron should be on the Cl. But I drew it on the O, which I thought made more sense because then the formal charge of O would be 6 - 5- 1 = 0 and Cl would be 7 - 6 - 1 = 0. In the answer key, O...

victoriatanaka1C

The way I think through these problems is to first write down what I'm given and what is unknown. You're given the velocity of an electron and the mass of an electron is constant. What is unknown is the wavelength of that moving electron. Next, I look for equations that involve my given and unknowns...

victoriatanaka1C

H-F is already a dipole, as H is delta positive and F is delta negative. N triple bond N is naturally equally charged, given N has the N charge as N. But, in the presence of H-Cl, a dipole because H is delta positive and Cl is delta negative, there is a slight pull on the charge of the Ns, making on...

victoriatanaka1C

In my notes, I wrote "instantaneous dipoles in two nearby rod-shaped molecules are closer and therefore stronger than those in two nearby spherical molecules." Pentane and 2, 2-Dimethylpropane have the same molecular formula but pentane is rod-shaped. This rod shape is stronger so it's har...

victoriatanaka1C

In Friday, Dr. Lavelle was explaining that the increasing strength of dispersion forces explains why F2 and Cl2 are gases at room temperature while Br2 is a liquid and I2 is a solid. He also gave other examples. In the periodic table we look at in class, it says the phases of atoms, but in the perio...

victoriatanaka1C

Dr. Lavelle said polarizability depends on the number of electrons and the size of an atom or molecule. I think he said polarizability decreases across a period and increases down a group. If I made a mistake, can someone point that out? Also, can someone explain what this means. I don't quite under...

victoriatanaka1C

As far as I understand, an "empty p-orbital" just means that the ground state atom doesn't have electrons in the p-orbital but it is available for bonding. I honestly don't know why this is the case, but I'm just taking it as fact. Sorry if this doesn't really help!

victoriatanaka1C

I'm also confused about this. I have in my notes psi (x, y, z) = Energy psi (x, y, z), but also psi: s, p, d, f. Maybe the x = s, y = p, and z = d?

victoriatanaka1C

And here's my solution for B! For these problems, plugging into the equation M = moles / volume is straightforward, but I think the hardest part is making sure you're using the right value for number of moles. Make sure to calculate the number of moles for the element you want by looking at its rati...

victoriatanaka1C

Here's my solution for A

victoriatanaka1C

Someone told me it's a good plan to keep compunds together that appear on both sides, and my TA told me H20, in most cases, requires an even coefficient. So using those guidelines, I compared PO4 on both sides and multiplied the one on the left my 2. With this, Ca and PO4 are in balance. Now there's...

victoriatanaka1C

Orbitals and subshells are not the same thing! Shells are determined by the value of n. Subshells are determined by the value of l (which can go from 0 to the value of n-1). Orbitals are determined by the value of m (which are valued between l and -l). So if you're given n = 4 and l = 1, m can be 1,...

victoriatanaka1C

I'm just looking for clarification - is the number of electrons that can occupy a given orbital equal to the number of possible values of m times 2?

victoriatanaka1C

The question asks in a) for POSSIBLE values of l but in b) and c) for ALLOWED values for m.

What is the significance of this difference?

victoriatanaka1C

m labels the different orbitals of a subshell and its allowed values are l to -l by decrementing l by 1 every time in between (Professor Lavelle did talk about this on Wednesday, so it makes sense that you're confused). So for a), l = 0 and m can only be 0, so there is 1 orbital. In b), l = 2 so m =...

victoriatanaka1C

Electrons move around their nucleus in a cloud, so if we think of them moving in a perfect circle (the standing waves oscillating around the circle), there has to be a specific number of wavelengths to fit perfectly in a circle. Because there has to be a specific number of wavelengths around the cir...

victoriatanaka1C

Would the answer be "the wavelength of a proton is x% larger than the wavelength of a neutron"?

victoriatanaka1C

I'm looking for clarification for 1.33 c. When calculating the E required (in order to calculate the wavelength), you have to combine the E required to eject the e- and the energy of ejecting the e-? How do you know when looking at the question that you need to combine both? I originally solved the ...

victoriatanaka1C

Does anyone have any tips for remembering the ranges? I know the order of energy for parts of the electromagnetic spectrum but I'm having a hard time learning the ranges of wavelength!

victoriatanaka1C

Molarity = moles of solute / volume of solute. Assuming both have 1 Liter of solution (or whatever equal number), the 0.5M solution would have more solvent then the 0.6M solution.

victoriatanaka1C

I also believe the same cover sheet we got for the first test is what we're getting for the rest of the tests! So, if I remember correctly, we didn't get the equation for molarity (and associated Minitial x Vinitial = Mfinal x Vfinal), but it seems to me that this class is very fair about equations ...

victoriatanaka1C

(This question also applies to part b). Basically I'm asking if what I got as the empirical formula is correct and how to properly order elements if it's not.

victoriatanaka1C

When i solved for part a, I got C4O4Os. The solutions manual says the answer is OsC4O4. How do I determine the right order to put my answers? I've just been listing the elements in the compound in the order they appear in the question, but this is (potentially?) incorrect in this example!

victoriatanaka1C

I noticed when Prof. Lavelle is calculating molar mass of compounds (or anything involving math), he writes the mass of O as 16 g.mol-1, but H stays 1.008 g.mol-1. Is there a guideline we should follow when rounding atomic masses?

victoriatanaka1C

Since the question is asking for a comparison (increase), you have to divide by the original. I did it by comparing what the mass % would be if it remained hydroxyapatite throughout, which would be 100%. Then I divided fluorapatite by hydroxyapatite (504.31/502.32) and found the difference between t...

victoriatanaka1C

Hi. Does anyone know if we have to know how to name chemical compounds only given their name? Like in question E9, it gives us "magnesium sulfate heptahydrate." I had to look up what the molecular formula would be for it. Do we have to be able to come up with the formulas on our own / does...

CHEMISTRY COMMUNITY

Search found 38 matches

Ammonium [ENDORSED]

Re: Coordination Compounds: Ligands [ENDORSED]

Re: My Understanding

Re: Breaking the Octet Rule

Re: Ligands

Re: Hybridization

Re: Oxidation number

Re: Formal Charge Meaning

Re: Notes Wed 5/23 and Fri 5/25

Notes Wed 5/23 and Fri 5/25

Re: Central atom and octet rule?

Re: 3.59a

3.59a

Re: De Broglie Wavelength on the Midterm

Re: Difference between Dipole-Dipole and Dipole-Induced dipole?

Re: Friday Class

Phases of molecules

Relationship in periodic table and polarizability

Re: Empty d-orbital?

Re: Schrodinger's Equation & Orbitals

Re: Test 1 Q.1

Re: Test 1 Q.1

Re: Test 1. Q 3

Re: 2.27 [ENDORSED]

# of electrons for a given orbital (homework 2.25)

Technicality for 2.19

Re: HW question 2.17 [ENDORSED]

Re: Circular Standing Waves

Re: HW 1.37 [ENDORSED]

Re: Homework Problem #33

Re: Electromagnetic Spectrum [ENDORSED]

Re: Molarity [ENDORSED]

Re: Memorizing equations [ENDORSED]

Re: Question F17 a

Question F17 a

Rounding atomic weight (general question) [ENDORSED]

Re: E. 35

Naming compounds