CHEMISTRY COMMUNITY

JinwooLee_1F

As I was solving 9C.5, I did not get b) and d). For b, can someone explain how one molecule can either be a mono- or bidentate ligand? For d), since there are four Oxygen molecules with lone pairs, shouldn't it be a tetradentate ligand? Thank you for your help!

JinwooLee_1F

I think in addition to doing the homework, solving out the practice tests really helped me. For example, there was the dino nugget practice test for the first midterm, and it helped me a lot because those were challenging problems that required me to master the concepts. If you think that homework p...

JinwooLee_1F

For hybridization, I think it is important to take a look at the electron configuration (the up and down arrows) to get a good sense.

JinwooLee_1F

Tetrahedral occurs when the shape is AX4E0. Square planar occurs when the shape is AX4E2. Fyi, in AXnEn, X is the number of bonds, while E is the number of lone pairs in the central atom.

JinwooLee_1F

For problems like these, just know that for strong acids, it will dissociate completely. Therefore, you just have to calculate the pH on the premise that all of the HCl has dissociated.

JinwooLee_1F

Weak acids and bases are the molecules that do not readily give off or accept protons, for example CH3CH3 or NH3 are weak acids, and I- and HSO4 are weak bases.

JinwooLee_1F

For e, the hydrogen atoms would not be in the same plane because they would be the farthest away from each other in order to make the molecule stable, and through being on a different plane they can be at the maximum distance.

JinwooLee_1F

Acids where the anion is stable when dissolved is a strong acid. In other words, the acids that readily give off their H+ is a strong acid. Therefore, acids such as HBr, HI are strong acids while HF is a weak acid.

JinwooLee_1F

Transition metal cations can form complexes because they have empty valence shell orbitals which can accept an electron pair from the lewis bases.

JinwooLee_1F

Those are the major functional groups we need to know, but I think if more functional groups come up during the lecture then we need to know about those as well.

JinwooLee_1F

You could try to petition but in all honesty I think it is too late. But trying does not hurt!

JinwooLee_1F

AX2E1 (<120) and AX2E2 (<109.5) is bent, AX2E3 and AX2E4 are linear and ~180.

JinwooLee_1F

It isn't really the phases, but the boiling points and the melting points. The general rule is that if intermolecular forces are stronger, the boiling points and melting points are higher.

JinwooLee_1F

The first bond is always sigma bond. The next bonds are pi bonds. For example, triple bond would be sigma bond + 2 pi bonds.

JinwooLee_1F

You would want to have more charge on the atom with greater electronegativity. If S has formal charge of -2 and O has none, it would not be correct as O needs a negative formal charge (since it has greater electronegativity than S).

JinwooLee_1F

Induced dipole - induced dipole is the weakest form of intermolecular force. An example of this could be an interaction between O2 molecules. They have a chance of having a weak dipole moment due to random distribution of electrons, which makes part of the molecule partially positive/negative, attra...

JinwooLee_1F

I don't think so but I think it is best to know the VESPR shape for conventional molecules just in case, like H2O.

JinwooLee_1F

CH3Cl and CHCl3 are obvious because if you look at the lewis structure since Cl is more electronegative, the molecule will have unequal "pull" of electrons. For CH2Cl2, you have to look at the VESPR model, which will show that they have unequal pull so it will have dipole moment.

JinwooLee_1F

I think IMF for induced-dipole-dipole is proportional to polarizability, which is affected by size and charge. So greater the size, greater the IMF for for induced-dipole-dipole.

JinwooLee_1F

I was looking up the VESPR model of H2O and it wasn't linear, which I expected it to be. Are there new models we are going to learn?

JinwooLee_1F

The solution manual is wrong, I used 9.109383 * 10^-31 and got 7.3 nm, which is the correct answer.

JinwooLee_1F

You should calculate formal charge when you are drawing lewis structures and have more than one possible structure. The one with the lowest formal charge is the most favorable, as it is the most stable structure.

JinwooLee_1F

It would take a lot of time to do formal charge for each lewis structures. It would be best to do them when there are two or more possible structures for one molecule, and you do not know which one is the most favorable one.

JinwooLee_1F

Most favorable structure when doing a lewis structure is the one that has the formal charge closest to 0.

JinwooLee_1F

By random chance, the electrons can be concentrated on one side than the other side. If this happens, then the atom will become slightly positive on one side and slightly negative on one side, creating a dipole.

JinwooLee_1F

For transition metals, do you always use that rule? Because Zinc has two valence electrons, but it has 2 in 4s and 10 in 3d.

JinwooLee_1F

This question asks you to find the valence electrons of Manganese. How do you find the valence electrons of transition metals such as Mn?

JinwooLee_1F

It can only accept hydrogen bonds, it cannot make hydrogen bonds with each other.

JinwooLee_1F

I think SF6 has Sulfur with 12 electrons, 10 electrons is not going to be the max number. I think it is more or equal to 12 electrons.

JinwooLee_1F

You have to do chemical bonding as we are finished with the quantum world.

JinwooLee_1F

Delocalized electrons are like the ones we saw during resonance. Since these electrons are not strictly associated with a single atom, they move freely. This is why NO3 has distance between single and double bond.

JinwooLee_1F

Since wavelength and mass is inversely related, calculating the wavelength for large-mass objects (such as baseball in one of our hw problems) result in extremely small wavelength, like 10^-34 m. Since these are basically close to 0, we cannot see these waves.

JinwooLee_1F

Uncertainty is 10mm, because if the uncertainty is something like 5 5+- mm, then it can range from 0 to 10 mm.

JinwooLee_1F

c is not possible. If n = 4, then l can only be 0,1,2,3 or more specifically up to n-1. Therefore, having both n = 4 and l = 4 is not possible.

JinwooLee_1F

I usually read the chapters after Dr. Lavelle goes over them to have a better understanding. Also, doing homework problems can provide additional practice and understanding.

JinwooLee_1F

When it is +-n, the uncertainty is 2n. Even for 5 +-2, the uncertainty would be 4.

JinwooLee_1F

Which equation do I use to solve 1B.5? Also, it says that the energy is 140.511 keV. What is this unit and do I have to convert this to Joules?

JinwooLee_1F

I personally found comparing moles much easier, as you have to keep in mind of the coefficients in balanced equation as well.

JinwooLee_1F

Go to quick links and then go to your posts. I think you should have at least 5 posts by every week to get full credit.

JinwooLee_1F

The method I use a lot is to balance the polyatomic ions first, then balance the non-organic elements, and then balance the organic elements.

JinwooLee_1F

They are the same equation, I think when putting them in the calculator you should put parenthesis around the exponent and lambda, see if that makes a difference.

JinwooLee_1F

Although we get every equation, be sure to memorize what each variable means as it can be confusing sometimes!

JinwooLee_1F

I don't know if this is an official efficient way, but I usually balance out the polyatomic ions/non-organic elements and then balance the organic ones.

JinwooLee_1F

I think we have to turn them in during the discussion starting from next week!

JinwooLee_1F

Yea I think the c stays constant, but the f and λ can change.

JinwooLee_1F

I think it is not plausible for theoretical yield to be less than the actual yield because if you weighed something wrong, that just means you got a wrong theoretical yield.

JinwooLee_1F

This is a lifesaver--I was very confused while reading this problem. Thank you for the clarification!

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