CHEMISTRY COMMUNITY

Karyn How 1J

For that question, you would compare the pH to the pKa of the acid to determine whether the reaction was favored more towards the neutral or ionized form. In this case, the pKa was higher than the pH indicating that the acid was found more in the neutral form.

Karyn How 1J

Dear Dr. Lavelle, Thank you for teaching 14A this quarter. I really learned a lot through your lectures and modules. Not a lot of professors have as many resources for their students as you do and it was extremely helpful it contributing to my learning experience. All the workshops and review sessio...

Karyn How 1J

You can calculate your grades with RodgerHub Grade Calculator if you want an estimate, although it might not be completely accurate.

Karyn How 1J

I think the final was worded a little better than the midterm even though there were some questions were kind of hard to understand. I think I was definitely more prepared for the final, but I can't really say much about how well I did until the scores come out.

Karyn How 1J

If I'm thinking of the right question, I think it was basic.

Karyn How 1J

I don’t think we need to know the specifics of bond order, I would recommend studying briefly if you’re unsure.

Karyn How 1J

Neutralization involves acids and bases and forms water as one of the products.

Karyn How 1J

I think you do especially for the ones that are used more often, like ferrate.

Karyn How 1J

I think there are a few common acids and bases that you can memorize easily and just know, but with the more complicated ones it would be the easiest to tell by looking at the chemical equation.

Karyn How 1J

For me, what I found that really helps is going to workshops for the extra review and worksheets. It’s really useful in regards of reviewing what we learned in lecture. Also go to your tas office hours if you ever have any additional questions or review the section covered in the textbook!

Karyn How 1J

Yes, the hybridization of an atom is determined based on the number of regions of electron density that surround it. You figure out the hybridization by counting the atoms connected to the central atom and the number of lone pairs

Karyn How 1J

I think the figures on the test were organic molecules and I'm pretty sure you won't need to learn how to draw organic molecules until the organic chemistry class.

Karyn How 1J

I'm not sure if this was what you were asking but: Vitamin B-12 plays a part in the normal function of the brain and the nervous system. It is also involved in the formation of red blood cells and helps to create and regulate DNA. The metabolism of every cell in the body depends on vitamin B-12, as ...

Karyn How 1J

I think it's due to the fact that cisplatin is polar and transplatin is nonpolar. The polarity probably impacts the cancer cells and is more effective in chemotherapy.

Karyn How 1J

The lone electron pairs around the central atom will try to repel the other electrons and try to remain as far away from other electrons as possible. The bonded atoms are pushed away by the lone electrons, decreasing the bond angles between the bonded atoms.

Karyn How 1J

Look at the chart for VESPR, it shows you where the angles measured and you should also take account of the planes that the atoms are on.

Karyn How 1J

The bond angles would be slightly affected by the lone pair of the molecule if it was located on the central atom. The lone pair would cause more repulsion and slight bending. Also if the molecules were both trigonal planar, but one of the molecules had a lone pair then that molecule would be a bent...

Karyn How 1J

I’m not sure if double bonds and triple bonds are indicated in any different ways but the drawing is called a wedge and dash projection.

Karyn How 1J

This question was asked during my lecture but I couldn’t hear everything Prof. Lavelle had said. For radicals, does it have any different rules when identifying the shape for VSEPR? Would the one lone electron count like the lone pair electron for VSEPR?

Karyn How 1J

The problem will probably specify whether the molecule is a cis or trans or the problem might indicate the orientation of dichloroethene and you would just have to know whether it is cis or trans to draw.

Karyn How 1J

Usually, you can tell by which elements are in the bond, especially for ionic when an element likely to form cations is bonded to one that's likely to form anions. You can also tell with the differences in electronegativity as well.

Karyn How 1J

I'm not completely sure about how much this topic will be covered but I think you should just mainly know that large, electron anions are more polarizable than smaller ones and that small, highly charged cations have high polarizing power, so just know a general periodic trend for it.

Karyn How 1J

You would look at the elements that are involved in the Lewis structure since their electronegativities and other traits, especially the tendency of elements to form ions will imply that the bond is ionic. The dipole moment depends mostly on the electronegativity strength because you'll know which e...

Karyn How 1J

I think it's going to be necessary for the most common shapes. There are also certain angles that are associated with certain shapes with a certain number of bonds. I'm sure Lavelle will establish which ones we have to memorize.

Karyn How 1J

Yeah, it should just be material we learned after the midterm.

Karyn How 1J

Resonance structures are the potential possibilities for what the Lewis structure for the chemical compound could be. Some Lewis structure have multiple bonds in different equivalent locations which is depicted through resonance structures.

Karyn How 1J

To draw a Lewis structure, you first look at the amount of electrons you have from the elements on the periodic table. Depending on how many elements you have, draw bonds between the elements first and confirm how many electrons are used in the bond. Afterwards, use the remaining electrons to draw i...

Karyn How 1J

For this week’s homework, I would just do it on chemical bonds outline just to be safe since that’s what we are currently learning.

Karyn How 1J

I think the charge of the anion also matters because the more electrons the anion is holding on to the more likely and easily it is to get pulled by the cation’s charge. Especially if the anion has multiple electrons, the nucleus will be able to exert as much control on its outermost electrons which...

Karyn How 1J

I think this might has to do with the 4th energy level and how energy level differences become smaller as it gets higher. I think the 4th level is close enough to the 5th energy level that maybe the 4d and the 5s are extremely close but the 4d is filled first because it’s lower.

Karyn How 1J

A single bond is counted as one shared electron since it's halved anyway through the equation. (S=2, 2/2=1)

Karyn How 1J

I think 2- is used more often especially when for the chemical formulas but if you're drawing a Lewis structure and you're just labeling the charge on the side I don't think it matters too much.

Karyn How 1J

The most important part about stable resonance structures is having formal charges that are 0 or are the closest numbers to zero. If there are negative charges, it's usually better if they are part of the more electronegative elements. Usually, you would also want to have the least electronegative e...

Karyn How 1J

When you draw lewis structures, make sure that you are aware of the number of electrons that are available from the elements and the octet rule. For NO3-, it was 24 electrons. For each element, you want to share until each of them has 8 electrons. So originally when there was only a single bond boun...

Karyn How 1J

To combine equations, you should make sure that they have a variable in common such as wavelength or maybe frequency, so you can substitute. Also keep in mind about the units that are used by the equations and that the equations are used for a related topic.

Karyn How 1J

The third quantum number is ml, which is the magnetic quantum number (orientation).

Karyn How 1J

The square of the wave function represents the electron probability distribution and how likely you are to find an electron in the orbital based on the Heisenberg principle. The wave function equation uses the concept that an electron with wavelike properties and indeterminacy in momentum and positi...

Karyn How 1J

I'm not sure if there is a set speed for electrons to move at but for light, it's stated that velocity is the speed of light since wavelength, frequency, and velocity can be measured. To find the velocity component, I think it would be either given so you can find the change in momentum if the elect...

Karyn How 1J

Yes, the Rydberg formula only works for Hydrogen Spectrum because it was based on experimental data for hydrogen. For the multi-electron systems, you would need a more complicated model.

Karyn How 1J

As the other replies stated, we don't need to understand the exact way the electron spins yet besides that it is either up or down. The reason why there is a need to denote whether the electron spins up or down is to follow Hund's Rule (which states that if there are more than one orbital in a subsh...

Karyn How 1J

De Broglie's equation is used to determine the wavelength of moving particles with momentum. It allows you to determine if the object has noticeable wavelike properties.

Karyn How 1J

For velocity, the units are meters per second so you would need to convert km.hr-1 to m.s-1 by using stoichiometry.
After you convert the units, you should get a value of around 34.72 and then you would plug it into the wavelength formula which is (6.626*10^-34)/(275*34.72).

Karyn How 1J

I would apply the sig fig rules at the point where you reach the answer so it keeps your calculations accurate. If you round after every step, it would throw off the numbers slightly. I base the sig fig rules based on the given numbers depending on what's being calculated and keep in mind which valu...

Karyn How 1J

When electrons jump down levels, they emit energy based on how many levels they are jumping. Since jumping from n=5 to n=1 is farther, the elctron would emit more energy. If the energy is greater, that means the frequency will be a lot higher than the transition from n = 4 to n = 2 (based off the E ...

Karyn How 1J

De Broglie's equation is derived from the equations for the speed of light (c), momentum (p), and Energy (E):

c = λν
v = c/λ

For a photon:
E = pc and E = hv = (h) (c/λ)
subsitute E = pc into the 2nd equation which makes:
pc = (h) (c/λ)
which leads to the De Broglie Equation:
λ = h/p

Karyn How 1J

No, I don't think so. States of matter don't impact how you balance your equations.

Karyn How 1J

Hi, so when you look at each molecule such as 2CO, make sure that you know that 2 is being applied to both carbon and oxygen. The reaction you wrote didn't work out due to the fact that 2 CO2 would mean that there are 2 carbons and 4 oxygens on the product side, however, on the reactant side, there ...

Karyn How 1J

Hi,

I would just use the entire number that is given from the periodic table, just for extra accuracy. I think it's best to reference the periodic table that's in the textbook since our homework probems are also in there.

Karyn How 1J

Hi!

I think your formatting is fine and it’s similar to how I did my homework. I think as long as you show the work and do the 5 problems, I don’t think there would be any problems.

Karyn How 1J

Hi all, I was in this class for a few weeks before it became necessary for me to go home on medical leave. I would recommend knowing the sig fig rules, even though they will not be graded harshly on the test. It is a useful skill moving forward and will definitely be useful in later chemistry and m...

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