CHEMISTRY COMMUNITY

rosemarywang4i

Why is water monodentate if it has two long pairs?

rosemarywang4i

What's 'cis' and 'trans' and how do they apply to naming ligands?

rosemarywang4i

For naming, which ions would we have to memorize for the exam? I know the common ones (e.g. for cyanide, sulfate, ammonia) but for question 17.31 it seems like we would also have to know ones like oxalato, which I haven't heard of before.

rosemarywang4i

In VSEPR, when you change the shared electrons to lone pairs, do you remove the axial or equatorial electrons? Does this depend on the VSEPR shape?

rosemarywang4i

How do you identify the intermolecular forces within a molecule? Are they somehow related to structure and polarity?

rosemarywang4i

For example, NH3 has a lone pair and 3 bonding electrons, and is sp3 hybridized.

rosemarywang4i

They should be taking place— the two sets of HW questions to be turned in for week 9 refer to discussions that meet on Thursdays and Fridays.

rosemarywang4i

What's the difference between electron geometry and molecular geometry? I understand that electron geometry seems to be more of like a blanket term for the different molecular geometries under it, but what's the structural basis for this?

rosemarywang4i

Hey! Does anyone know what our third exam will entail/ what chapters and topics we should study? Is it everything from the midterm to this week (so like bonding, intermolecular forces, shape, and hybridization?)

rosemarywang4i

For any calculations we will be given the experimentally-derived bond lengths (e.g. the lengths of single and double bonds which we will have to average out for actual bond length).

rosemarywang4i

It doesn't mention that explicitly on the outline/we haven't gone over it in class but it's required for some of the homework questions and nonetheless helpful for determining shape!

rosemarywang4i

Question 4.5 in the 6th edition asks:

(a) What is the shape of the ClO2 ion?
(b) What is the expected OClO bond angle?

I'm a little confused about the process of determining the shape of the molecule from the Lewis structure and was wondering if anyone has a good step-by-step process that works.

rosemarywang4i

The molecule is more stable that way as the formal charges of S and Cl are all zero.

rosemarywang4i

Many of the textbook problems ask to find resonance structures for compounds— are there any tricks to how we can find ALL of the resonance structures? So far I've just been drawing out a lot as trial and error but I was wondering if there's any other ways to go about this.

rosemarywang4i

^ that and also, if a question asks you to determine actual bond length from several givens it's just the average.

rosemarywang4i

It's because nitrogen's p orbital is half filled, so it's more stable than oxygen and thus requires more energy to remove an electron.

rosemarywang4i

In addition to that, it is pretty common for HW or practice questions to ask for all the resonance structures of a molecule, so you would need to do that when asked.

rosemarywang4i

Kekule structures seem to be Lewis structures but without lone pairs or formal charge indicated on them.

rosemarywang4i

I think we can use either electronegativity or ionization energy to determine the central atom. We would generally take the atom with the lowest electronegativity because it is the one that is most conducive to sharing electrons and forming bonds, with exceptions. In class, I believe we were taught ...

rosemarywang4i

In class, Dr. Lavelle said we would be primarily concerning ourselves with only the s-block, p-block, and the first row of the d-block as those are the elements most commonly found in organic compounds. So we probably don't have to memorize the shapes of the f-orbitals.

rosemarywang4i

It's just been experimentally established that in those specific configurations, the atoms are at lower energy levels, so it's the default.

rosemarywang4i

There doesn't seem to be a rhyme or reason as to why those two elements' electrons fill differently, other than the fact that it has been experimentally established that in that configuration they are at lower energy states and thus more stable. It doesn't hurt to memorize them, but I'm not sure if ...

rosemarywang4i

Constants will always be given on the front page for exams :)

rosemarywang4i

For clarification: if delta E is negative we have to switch it to a positive value when it accounts for E in an equation, right? Why do we do that?

rosemarywang4i

Is there any difference in using the two (like would one be more intuitive or simpler to use)?

rosemarywang4i

In question 18 of the video module's post-assessment for the Heisenberg uncertainty principle, we are asked the following: The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty ...

rosemarywang4i

Question M19 asks: "When 0.376g of caffeine was burned, 0.682g carbon dioxide, 0.174g water, and 0.110g nitrogen were formed. Determine the empirical and molecular formulas of caffeine, and write the equation for its combustion." I know that when something is combusted, it is reacted with ...

rosemarywang4i

Dr. Lavelle said in lecture today that the homework is supposed to be designed to be flexible to how we learn— since there's a test this week, the homework questions we submit this week can be the ones from Review of Chemical and Physical Principles because it'll help us to review as long as they're...

rosemarywang4i

I got you too! Also, if you view the Audio/Visual Module for the Photoelectric Effect, it's essentially the same lecture that was taught in class today.

rosemarywang4i

If the number were 1.23, I would try multiplying everything by a factor of 4 or 5 to get closer to a whole number. See which seems to work better for the other coefficients!

rosemarywang4i

I'm not quite sure when to round off my significant figures when doing a problem that has multiple mathematical steps. For example, question E1 asks firstly for the number of atoms in 1.00mol Ag and then to multiply that number by 144pm to get a final length. I understand that I would have to multip...

rosemarywang4i

Apparently after we go over polyatomic ions we will be expected to know them, so eventually we will need to memorize/have some idea about nomenclature. But for now, everything will be given to us.

rosemarywang4i

There are lots of different systems for ordering the elements in a chemical formula— but most commonly they are listed alphabetically after carbon being the first and hydrogen second, or in order of electronegativity. For ionic compounds, it's usually the cation first followed by the cation. IUPAC f...

rosemarywang4i

I'm pretty sure that 'formula unit' is another term for the empirical formula. But perhaps if you link some of the practice problems we can get a better idea of what you're confused about.

CHEMISTRY COMMUNITY

Search found 34 matches

Why is water monodentate?

Difference between cis and trans

Which ions do we have to memorize?

Changing shared electrons to lone pairs

Identifying intermolecular forces

Re: Lone pairs

Re: Discussion

Electron geometry vs Molecular geometry

Exam 3 Topics [ENDORSED]

Re: Bond length question

Re: Need to know VESPR equation? [ENDORSED]

Question 4.5 (Determining shape from Lewis structure)

Re: Question 4.11

Finding all Resonance Structures

Re: Bond Lengths

Re: O vs N [ENDORSED]

Re: Resonance hybrid

Re: kekule structure?

Re: electronegativity in lewis structures

Re: Orbitals

Re: Building- Up Principle

Re: Two exceptions

Re: Work Function

Re: Change in energy

Re: Rydberg Equation

Indeterminacy in position

Question M19: Empirical and Molecular formula of caffeine [ENDORSED]

Re: Chapter 1 Homework

Re: Missed today's lecture (10/8) could anyone share their notes?

Re: Going from empirical to Molecular formula

Sig Figs... when to round?

Re: Knowing Chemical Compounds

Re: Homework Question F17(6th Ed)

Re: Formula unit