CHEMISTRY COMMUNITY

Guzman_1J

Is the reason SiCl4 has a higher boiling point that they have stronger dispersion forces? They are both nonpolar molecules, which means their dipole-dipole forces cancel out, this has an effect on boiling point or what is the reason for this?

Guzman_1J

When do we put "ion" at the end of the name of the complex and is that the only other name we put there besides the name of an element?

Guzman_1J

Linear, trigonal planar, tetrahedral, trigonal bipyramidal, octahedral, and square planar shapes are symmetrical which means that molecules of these shapes are nonpolar if all atoms bonded to the central atom are the same. Is it a general rule that all atoms must be the same? If there is a molecule...

Guzman_1J

Alex Tchekanov wrote:Yes, if one of the attached atoms is different, it is polar.

So if all the atoms are the same, then it is nonpolar?

Guzman_1J

Nohemi Garcia 1I wrote:Tetrahedral I believe is one of these examples. It tends to be polar but in cases such as CH4, the structure become neutral. This is because all of the surrounding atoms are the same and their dipoles "cancel out."

Is this the only shape with this characteristic?

Guzman_1J

Jacey Yang 3I wrote:A molecule is polar when the central atom has lone pairs and the atoms attached aren’t the same, so the dipoles don’t cancel.

Is this for all molecules?

Guzman_1J

Can anyone tell me the general rules about polarity when it comes to shape? I remember Lyndon mentioning during review that certain shapes are always polar unless they're all the same element but was not able to catch everything he said.

Guzman_1J

Why does NSF3 have a higher boiling point than SF6?

Guzman_1J

Can someone explain how we knows what the bond angles are? I'm still confused about how we know that, or like how we know that an angle is less than some other angle(for example when they say that an angle is <120, how do they reach that conclusion)?

Guzman_1J

From what I read on 3F.5, hydrogen bonding can happen between H and N, F, or O molecules, but only if the H is already attached to a N, F, or O? So hydrogen bonding is technically not possible if that does not happen(as in, it would just be a regular interaction if one free H attached to an O, and ...

Guzman_1J

From what I read on 3F.5, hydrogen bonding can happen between H and N, F, or O molecules, but only if the H is already attached to a N, F, or O? So hydrogen bonding is technically not possible if that does not happen(as in, it would just be a regular interaction if one free H attached to an O, and n...

Guzman_1J

How would the description of a triple bond between C(sp3 hybridization) and N(sp hybridization) be described? Like the bond between C and H can be described as sigma(Csp3, Hs), would the bond between C and N then be described as just a pi bond (pi(Csp3, Nsp), or would I have to include that it also ...

Guzman_1J

How do you assign hybridization to a lone pair? I get confused by that question, can someone please explain?

Guzman_1J

Is hybridization affected by lone pairs? Like in AsFe3, does As have an sp2 hybridization because it makes three bonds with Fe, or does it have sp3 hybridization because it also has a lone pair?

Guzman_1J

How are we supposed to know whether the wavefunction of an orbital is either positive or negative? Do we have to know how to do that or is it enough by knowing what the hybrid orbitals are called? For example, in the book in 2F.2 they gave the example of Carbon, and its four hybrid orbitals- h1=s+px...

Guzman_1J

So hybridization only rises as a result of electron promotion in an element?

Guzman_1J

Rosa Munoz 4D wrote:Yeah! Where do you want me to send them to you?

My email is yesigr918@gmail.com
Thank you so much!

Guzman_1J

For this class, can we fully go with the assumption that ALL single covalent bonds are sigma bonds, double bonds are one sigma and one pi, and triple bonds are two pi bonds and one sigma bond? Or are there other rules to figure out what type of bonds there are in an interaction?

Guzman_1J

What helped me was reading the textbook! Lecture makes it hard to absorb everything in for me, specially since the slides are just blocks of writing and going through the textbook instead lets me go over the material easily and at my own pace.

Guzman_1J

I was going through my notes and there's something I didn't fully understand: "oxoacids more readily lose H+ if resulting anion is stabilized by electron withdrawing atoms which delocalize and stabilized the negative charge". Could someone explain how the electron withdrawing atoms influen...

Guzman_1J

What exactly is the coordination sphere? Is it only to describe the space taken up by the bonded atoms?

Guzman_1J

Does hybridization only happen between the last orbitals of the elements whose orbitals are overlapping, or can it also happen between orbitals that are closer to their nucleus?

Guzman_1J

So is hybridization the overlap of orbitals between two elements and it's also possible for only a single element(the example in class about CH4, C had sp3 hybridization)? How exactly does hybridization work? Where they overlap its like they become one orbital and share the number of electrons betwe...

Guzman_1J

I was not able to go to lecture on Monday so I was wondering if anyone could share their notes with me please? Or does Lavelle upload his lecture presentations somewhere? I feel like I really need them because I felt a little lost on Wednesday's lecture :( please help out a fellow student

Guzman_1J

Is hybridization just a blend of all resonance structures or is it atoms making certain bonds? I'm still a little confused on the topic.

Guzman_1J

What kind of atoms are ligands? From the lecture in class, what I understood is that ligands are attached to a central atom, but is the name given because they're a different type of atom or something?

Guzman_1J

Are all single bonds sigma bonds and double bonds pi and sigma?

Guzman_1J

In regards to the book, until what topic will be covered on Test 2? Is it just going to be Molecular Shape and Structure(2E-F) or is it going to go past that into Coordination Compounds and their Biological Importance?

Guzman_1J

Why was the ground state of calcium given as Ca2+? I got this question wrong for the midterm even though I wrote the right electron configuration for Ca.

Guzman_1J

Can we still turn in homework assigned for chemical bonds for this week?

Guzman_1J

Sorry but I've been looking through emails and the syllabus and i havent found where the test room is at. Where is the test at? :/

Guzman_1J

Can someone explain how they got to the right answer for 12b and c from the practice problems we were given?

Guzman_1J

Which are the elements that can have an expanded octet and by how much? I know P is 10, S is 12, but what about the other ones

Guzman_1J

How did y'all solve problem #1 in the practice problems given? I keep getting the wrong answer and I need some help!! I'm finding the moles of CO2 and H2O to get the grams of C and H, but once I subtract the grams to find grams of O and get the moles I get .012 mol for C, .0169 mol of H and .0048 mo...

Guzman_1J

Is electron affinity the same as electronegativity or does it refer to something else? If so, do we need to know about it?

Guzman_1J

Do we need to know anything about the second ionization energy of an element, or are we good with only the first ionization energy?

Guzman_1J

Natalie Nartz 4F wrote:I don't believe we'll need to memorize this for the exam. I think Lavelle even mentioned an alternative equation to use instead.

What was the alternative equation?

Guzman_1J

Is this going to be on the test? I don’t think we went over this one In detail.

Guzman_1J

Do we need to know the Orbital angular momentum equation?

Guzman_1J

When do we use En=-hR/n^2?

Guzman_1J

does UV wavelength start at 10nm or 100nm?

Guzman_1J

How much about chemical bonds do we need to know for this test? Is all of the Learning Outcomes from chemical bonds listed on the pdf on the website going to be on the test?

Guzman_1J

Have we gone over this equation En =((h^2)(n^2))/(8 m L^2)? We were not assigned any hw problems from 1C but the equation is in the sheet in the website. Have we gone over it in class?

Guzman_1J

For the Quantum World? Where it says to "Omit 1C and Table 1D.1"? I'm just wondering because En =((h^2)(n^2))/(8 m L^2) is an equation that is in the Constant and Equations sheet on the website, but Appendix 1C is about scientific notation, I mean Topic 1C on page 23 because we were also n...

Guzman_1J

I did not see Topic 1C homework problems in the syllabus. Does this mean we do not have to know the stuff on that part for any tests?

Guzman_1J

Which is the Rydbger formula? In the texbook it shows it as 1/wavelength=Rh((1/n1^2)-(1/n2^2) but while solving a problem in discussion that asked for it, a student used En=hR/n^2 but I did not see that formula in the texbook for part 1A. I have missed lecture in one of the past weeks so I might hav...

Guzman_1J

For Example 1B.5 in textbook Using the uncertainty principle, when grams and mm/s is being converted into SI units they are multiplied by 2 once they have been converted but the textbook does not explain why. Does anybody understand this problem? I know how we are supposed to use the equation, it's ...

Guzman_1J

Do we need to know the kinetic energy equation given for when an electron is ejected?

Guzman_1J

Does intensity of radiation have to do with its frequency?

Guzman_1J

What does the emission spectrum tells us and how is this different from what the absorption spectrum shows? I'm a little confused about the emission spectrum, does it only work for the hydrogen element(since the lyman and Balmer series are just for hydrogen(?))?

Guzman_1J

For this class, do we need to know the exact frequency and wavelength for the colors of visible light(violet to red)?

Guzman_1J

Can someone explain the differences between hertz and frequency? From the book, they sound like the same thing but is hertz just the unit, so if we are asked for the frequency we have to answer in hertz or how exactly are they related?

Guzman_1J

Yeah I'm not sure how to get 2.99 mL, but that's what the TA put on my paper should have been my answer.

Guzman_1J

Up until what topics would we be covering for Midterm 2? Is it gonna be cumulative with stuff all the way from Week 1?

Guzman_1J

For this week's homework, can we still turn in homework problems from The Quantum World section in the syllabus?

Guzman_1J

So n=1 can hold more than two electrons?

Guzman_1J

I don't understand exactly how finding the uncertainty in an electron's velocity to be greater than the speed of light tells us that its not localized at the nucleus. How can we come to that conclusion from that information?

Guzman_1J

So the Heisenberg uncertainty principle has to do with BOTH the physical limit to the min. size that atoms can exist, and to the momentum and position of an electron? How exactly are they related?

Guzman_1J

Yes, I got 3x10^-6mL, when the answer should have been 2.99 mL.

Guzman_1J

Could anybody who understood problem 5b explain the right way to do it? I got right the first part of the problem (5a) but i got b wrong, and I was wondering where I went wrong.I used M1V1=M2V2 to solve the problem with M1=.21, M2=2.68x10^-3, and V2=.24.

Guzman_1J

So every n has a certain number of s(1),p(3),d(5), & f(7) orbitals, and these orbitals can each hold up to two electrons? Does this mean that even n=1 has all these orbitals?

Guzman_1J

How do we know when ms is negative or positive 1/2?

Guzman_1J

the electron gains energy when n increases

Guzman_1J

You don't have to find the mass, as its given: 1.675*10^-27 kg

Guzman_1J

when an e- moves further away from the nucleus, it would need energy to do this, thus it gains energy. To move closer to the nucleus, the opposite is true.

Guzman_1J

All of the answers seem to be correct. When an electron moves to a bigger orbit, it gains energy. The radius of the atom also increases because an electron moving to a bigger orbit(from a small n to a big n) makes the size of the atom bigger.

Guzman_1J

Is there a way someone can explain to me how electrons can be both a wave AND a particle?

Guzman_1J

Sorry but why is 0.0001 and 0.00010 considered to have only 1 and 2 significant figures respectively? Why is it not 4 and 5 instead?

Guzman_1J

I went to a Step Up session today and I was told that we didn't necessarily had to convert all units to SI units(like grams to kg) if the rest of the units were the same(as in if everything was already written in g, then we did not have to convert units), is this true for the exam?

Guzman_1J

I was wondering if molarity and dilution calculations would be part of the test? I'm confused about this since I didn't think it was one of the topics we had to review from the Audio Visual Focus Topics.

Guzman_1J

I'm not sure if this is the place to ask this, but I was wondering if anyone could share their experience attending the Peer Learning sessions. I did not enroll for any last year but I was wondering if it would be more advantageous to do so for this class.

Guzman_1J

What topics will the first test be covering?

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