CHEMISTRY COMMUNITY

Elena Maneffa 1E

Thank you so much for all your help. This is extremely appreciated.

Elena Maneffa 1E

Does anybody have any tricks or a cheat sheet for naming compounds?

Elena Maneffa 1E

The question is:

Name each of the following complex ions and identify the oxidation number of the metal
a. [Fe(CN)6]^4-

b. [Co(NH3)6]^3+

c. [Co(CN)5(OH)2]^2-

d. [Co(NH3)5(SO4)]^+

When do you know when to write cobalt vs cobaltate or iron vs ferrate?

Thanks :)

Elena Maneffa 1E

Ligands on the same side of a molecule is cis and the opposite is trans.
This is why we cis and trans fat.

Elena Maneffa 1E

We have to memorize them.

Elena Maneffa 1E

AX3E2 means that an atom is bonded to 3 other atoms and also has 2 lone pairs.

If it had just one lone pair it would be trigonal pyramidal but because of the second lone pair, it changes the angles and is now considered to be T-shaped.

Elena Maneffa 1E

When we find the lewis dot structure for BrF3 we realize that it is T-shaped. It is bonded to 3 atoms and has 2 lone pairs. The electron density or electron arrangement is 5. The atomic orbitals has to match the number of hybrid orbitals. In sp^3d: there are 5 hybrid orbitals.

Elena Maneffa 1E

Can someone please explain 2.45 from the 7th Edition to me?
The question is as follows.
Consider the bonding in H2C=CHCHO.
a) Draw the most important Lewis structure.
b) Identify the composition of the bonds and the hybridization of each lone pair; for example, by writing sigma(H1s,C2sp^2).

Elena Maneffa 1E

What is the difference between electron density and shape? Why do we find two different names for the same molecule?

Elena Maneffa 1E

Click "Quick Links" in the top left corner and then "My Posts."

Elena Maneffa 1E

Yes, lone pairs do affect the shape and structure. For example it can determine the difference between linear and bent.

Elena Maneffa 1E

Discussions on Wednesday are not canceled.

Elena Maneffa 1E

Test 3 will cover : "End of Bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see Syllabus and Outlines for details)."

Elena Maneffa 1E

I thought test 3 was going to be during Week 8.

Elena Maneffa 1E

Usually, in a bond length, specific bond lengths will be given to you. For example, let's say you are given that a C=0 bond is a given length, x. If you see that in your lewis structure you have in total three bonds and each of these 3 bonds are a C=0 (C double bonded to an 0), then you know all the...

Elena Maneffa 1E

Yes, they are the same thing. You can use reactant and reagent interchangeably.

Elena Maneffa 1E

Test 3 will be during your discussion session on Week 8. The final exam is scheduled for the 9th of December.

Elena Maneffa 1E

Do we need to buy a blue book for the midterm or will the midterm be like our usual tests without the blue book?

Elena Maneffa 1E

Because of resonance, you can create various different structures of the same compound. But the version with the lowest formal charge is the most suitable. For this reason, we calculate formal charge.

Elena Maneffa 1E

H is never a central atom, so you know that for sure. You then look at the other two elements, C and O. C is the central atom because it has the lowest ionization energy. So connect C and O with a bond, and then put 3 H's on the C and one H on the O. Don't forget to add 2 lone pairs to O.

Elena Maneffa 1E

For 1B 15 c : The question is: What is the wavelength of the radiation that caused photoejection of the electron? So first we have to find the Energy of this wavelength. We know the threshold energy from part 1B 15 b=1.66x10^-17. We also know that: Energy (per photon) - threshold energy =Ek We can r...

Elena Maneffa 1E

Dr. Lavelle said that the best way to study for tests is to make sure you can do all the homework problems. Also, on the class syllabus, it says that one of the questions on the test is from the homework problems.

Elena Maneffa 1E

How do we solve 1.A.15 without using the Rydberg equation? I've been told we have to use En=-hR/n^2 but I am a little lost.

Elena Maneffa 1E

Wait, actually, sorry. My TA said we can't use the equation from the book. We are supposed to use another one, so the above explanation is wrong. Sorry.

Elena Maneffa 1E

For a line at 102.6nm, we know that n1=1. Then use the equation c=(wavelength)(frequency), but rearrange it to look like: v= c/(wavelength) So: v=(2.998x10^8)/(102.6x10^-9) =2.922x10^15 s^-1. We then need to find n2. Use this equation: v=R((1/n1^2) - (1/n2^2). Then you will get this if you rearrange...

Elena Maneffa 1E

Make sure you talk to your TA, but any 7 problems from outline 2 should be fine!

Elena Maneffa 1E

Test 2 is about outline 2. Do the modules and the problems from the hw about the quantum world. I'm pretty sure the tests aren't cumulative, that is until we get to the midterm or final.

Elena Maneffa 1E

I don't know if points will be taken off, but I would try to include units as much as possible just in case. We are supposed to show work, so this might contribute to that.

Elena Maneffa 1E

I don't think this will be a key point on Test 1. I can't say for sure, but I feel like he will give us the name of the compounds. Probably for future tests, we will need to know them though.

Elena Maneffa 1E

I don't understand how to solve this problem. Can somebody help? 5.00 g of KMnO4 is dissolved in a 150.00 mL flask of water. If 20.00 mL of this solution is removed and placed in a new 2nd 250.00 mL flask and filled with water, what is the concentration of the solution in the 2nd flask? Molar Masses...

Elena Maneffa 1E

How can values be accurate but not precise? If all the values are accurate (close to the true value) how can they still be not precise in relation to each other Values can be accurate but not precise because each measurement may be close to the true value (relatively) however not relatively close e...

Elena Maneffa 1E

I think that you should include them. You might get a point off on a homework or a test for not doing so.

Elena Maneffa 1E

From my understanding, I think sig figs represent all the digits, not just the figures after the decimal point. 1.02, for example has 3 sig figs.

CHEMISTRY COMMUNITY

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Re: FINAL PRACTICE - Lyndon's Churro Review Session [ENDORSED]

Tricks/cheat sheet

7th edition 9.C1

Re: Difference between cis and trans

Re: Naming Coordination Compounds

Re: T shaped

Re: Question from textbook

2.45 7th Edition

Electron Density vs Shape?

Re: How to find my posts

Re: VSEPR

Re: Discussion on Wednesday

Re: Test 3

Re: Test 3 dates?

Re: Bond Lengths

Re: Reactant vs. Reagent

Re: Test & Exam Dates

Blue Book Midterm

Re: Formal charge purpose

Re: Central Atom

Re: 1B 15 7th edition part C

Re: Studying for tests/midterm

1.A15. (7th edition)

Re: 7th edition HW Problem 1.A15

Re: 7th edition HW Problem 1.A15

Re: Homework

Re: Test 2

Re: Units

Re: Compound Names

Online Module Problem Dilutions

Re: Accuracy vs Precision

Re: notation

Re: Do sig figs only refer to decimals?