CHEMISTRY COMMUNITY

DMuth_1J

He seems to like putting all of the exceptions on the assessments. I will be looking at a lot of the rules that must be followed when calculating / carrying out certain processes, but more emphatic on the things that don't follow the rules (which will probably also cause me to better know what the r...

DMuth_1J

It has to do with fulfilling the octet and usually occurs in ionic compounds.

DMuth_1J

Just to clarify, I think it's a typo, but pH= -log(H+) and pOH= -log(OH-). Make sure the pH is associated with the H+ / H3O+ and the pOH is associated with the OH-

DMuth_1J

The 0-14 scale is most of the time all you will have to worry about, but don't be alarmed if your calculations give you a number slightly below 0 or slightly above 14. It is possible in extremely strong acids / bases, but is rare.

DMuth_1J

The only time you would ever really have an oxidation number is in transition metals because all the other elements have consistent values

DMuth_1J

I'm not too sure if we will need to know much more besides water in terms of the amphoteric compounds

DMuth_1J

What happens if the metal is negatively charged? Is it treated as the ligand?

DMuth_1J

are all the molecules inside the coordination complex interacting intramolecularly? Or do intermolecular interactions come into play as well?

DMuth_1J

I thought hybridization was reliant upon the number of bonds, not just the electron density. Do lone pairs increase the hybridization as well?

DMuth_1J

if coordination number is the number of bonds, then what is valence?

DMuth_1J

What is the order of the metals / iond / ligands / other components of coordination compounds?

DMuth_1J

Always remember that acids are negative and bases are positive. Acids will give protons away and accept electrons (causing the charge to become more negative) while bases will accept protons and give electrons (causing the charge to become more positive).

DMuth_1J

You can predict that the where the repulsions will occur more, pushing the other bonded atoms away. That lets you know that, qualitatively, there will be a change in the bond angles (of which you can predict of it will be more than or less than the typical, nonpolar bond angle). However, you cannot ...

DMuth_1J

It will not have a subscript. It is the central atom.

DMuth_1J

the bonded electrons are slightly more stable and have lower repulsive forces because of such, considering they are distributed between two atoms. Lone pairs repel each other more strongly because their domain is only the orbital of the single atom to which they are bound.

DMuth_1J

He taught us as bent so I would used that term instead of angular

DMuth_1J

both molecules must be polar, not just one. Otherwise it would be a dipole - induced dipole

DMuth_1J

For dispersion forces, be sure to know all the names they can be called (induced dipole - induced dipole, london dispersion forces, van der waals)

DMuth_1J

Do we know if the test will be cumulative?

DMuth_1J

They are considered electron density and have an effect on shape. Dr. Lavelle mentioned that he was careful in his word choice because he wants us to know that shape is not only determined by bonds, but also the lone pairs.

DMuth_1J

So far he has only gone over six, so I would imagine those for sure (especially considering they are considered the basic ones without lone pairs). As he teaches more I believe we will be responsible for all the ones he shows us.

DMuth_1J

The dipole moments in hydrogen bonds are also what allows various hydrogen-bond molecules to interact with each other (as is the case in water). The dipole moment creates partial charges that attract the partial charges of other molecules.

DMuth_1J

The bond angle allows the most space between electrons as is possible. And yes, I believe we have to memorize them.

DMuth_1J

We will be asked to identify the structures, so learn and memorize them, but you don't have to be able to draw it.

DMuth_1J

They're synonymous and occur when lone pairs and a linear structure are involved in the same atom.

DMuth_1J

atoms are more stable when electrons are as far apart as possible because there are less repulsive forces. This is always the case. Think about when you and your friend are pulling on something with all your strength. When one of you lets go the other goes flying. If there were less force pulling, t...

DMuth_1J

I'm not sure if this is what you're asking, but we can only be confident to a certain degree of both the position and momentum of an electron at the same time. The uncertainty principle is that (position)(momentum), when momentum equals mass times velocity, must be greater than or equal to h, Plank'...

DMuth_1J

I wouldn't go out of your way to memorize anything, personally. If you're expected to know it, it's because we have used it so many times and encountered it so repetitiously that it would be hard not to know it (like water, carbon dioxide, etc.) Plus, most questions usually give the formula.

DMuth_1J

I don't think we have to worry about it because he glossed over it, commented on his dislike for it, and continued to show us alternative calculations that we should be using instead. We also don't have any homework problems on it, so I say skip it.

DMuth_1J

Yes, pay attention to the magnitude of the energy values. The greater the magnitude, the stronger the bond as it requires more energy to break that bond

DMuth_1J

Always take from the highest energy state. Once you get to the D orbital, you write the electron configuration 3d4s and so forth (4d5s, 5d6s). You write it like this because at this point the s orbital is higher energy than the d orbital. Always take from the highest, so start from the outside and g...

DMuth_1J

Pay attention to formal charge. Also, sometimes you have to use a double bond to satisfy the octet rule

DMuth_1J

In most cases, dipole dipole interactions are weaker than London Dispersion Forces as the former uses charges and the latter is the result of temporary dipole moments that occur between molecules.

DMuth_1J

Electronegativity is a measured value while electron affinity is not. They are separate because electron affinity is a concept that combines electronegativity and ionization energy to present information more comprehensibly.

DMuth_1J

Yes. There are five orbitals, which is of the nature of the D orbital, as there are three p orbitals and one S orbital. Each orbital holds two electrons, so the D orbitals have the capability to hold 10 electrons

DMuth_1J

I don't believe you should be concerned about which orbital has the highest ionization energy, but more focused on the elements themselves. The ionization energy would increase as the energy level of the orbital decreases. Therefore, the S1 orbital has a higher IE than P1 and so forth.

DMuth_1J

No, Florine does

DMuth_1J

I remember there being a specific number, and am tentative in saying 10^-15 m

DMuth_1J

It isn't something you have to worry about too much. You're not going to have to calculate or find the direction of spin, just know that in the same orbital two electrons cannot have the same direction spin.

DMuth_1J

Hello, I was wondering what the exceptions are for the d orbital. I understand that, when electrons are removed, they are removed from the s orbital before the d orbital. I also remember something about the s orbital filling before the d, except for certain elements (copper and silver?). Could someb...

DMuth_1J

If the mixing of equations is confusing, then I don't think it is necessary to. You can use the base equations and just go through it systematically. I usually tend to do this, comparing what I have been given to what I need to get. Then, I will find what I'm missing in one equation and use another ...

DMuth_1J

It would also be helpful to know how to derive the equation because you can use the base equations as opposed to the complete, derived one.

DMuth_1J

Hello, I was wondering if we are expected to memorize the wavelengths / frequencies of the different kinds of light. I know we are expected to remember that the visible spectrum is around 400-700 nm, but what about the others like UV, x-ray, y-ray, infrared, etc. Will we need to memorize the shortes...

DMuth_1J

The speed of light is a constant. No matter what kind of light or what variant of light, the wavelength multiplied by the frequency of a specific light sample being studied will always equal this constant 2.98x10^8 m/s

DMuth_1J

For part C, the orbitals are the same energy level and same mathematical shape. They are identical, only differing in the directions they face. If you think of an atom like a circle, the direction they face doesn't change the electron's ability to inhibit interaction with another atom. Basically, it...

DMuth_1J

For part C, the orbitals are the same energy level and same mathematical shape. They are identical, only differing in the directions they face. If you think of an atom like a circle, the direction they face doesn't change the electron's ability to inhibit interaction with another atom. Basically, it...

DMuth_1J

Try looking up Jessica Martin in youtube. She was my AP Chem teacher in high school and I feel as though I have a relatively good grasp of the information because of what she had taught me.

DMuth_1J

The uncertainty equation relates to objects that are incredibly small, like an electron. In class the example used was of the photon laser that is used in grocery stores. For us, because we are massive compared to an electron, we get hit by a photon and nothing happens. When an electron gets hit by ...

DMuth_1J

Are you making sure that your units are cohesive throughout the problem? For example, are you dividing KJ by J?

DMuth_1J

I don't believe the intensity of black body radiation will have an effect on wavelength as, at the point where the black body is reached, it encompasses every possibility. I remember something being said about black body being hypothetical, in which case it would behave like a photon right?

DMuth_1J

I believe so. The ones that were posted on his website, right? I believe that there are no more. I was doing the same thing but from here forward I believe there are no recordings / edited lectures online for us to reference.

DMuth_1J

Are you talking about the diagrams where there was a pulsating wave-circle on an X and Y axis? If so, it was meant to demonstrate how the wave must be connected. There is no possibility, it is "not allowed," for the energy level to change. The broken wave-circle is not allowed because ther...

DMuth_1J

In most circumstances, when an electron is emitted it will have extra energy as a result of the energy difference between the threshold energy and the energy of the photon. This will result in the electron being launched into the detector, which allows for the electron to be detected. It is possible...

DMuth_1J

If you already have a light source that is having a photon interact with an electron, it means that the photon has the frequency (its energy is above or at the threshold energy) required to eject an electron from that surface. Therefore, when you increase the intensity of that same light source, the...

DMuth_1J

It's important to realize that the terms "high" and "low" are relative to the metal by which the experiment is being performed on. The frequency must be high enough, or the wavelength short enough, to eject an electron from a metal surface based on the threshold energy. If the th...

DMuth_1J

I like to look at it according to the words "work" and "threshold." The work of the function is what is being done, or the action. The threshold is the point that must be reached. They are often synonymous because once the threshold energy is met the work function is performing.

DMuth_1J

I think I remembered seeing somewhere that Sundays are the last days to post for the week before. If you post on Sunday it will count for the previous week and then the posts Monday will count for the following week that has just begun.

DMuth_1J

Algebraically you could isolate n2^2 in either formats

(1/n2^2)= (1/n1^2)-(V/R)

or

(n2^2)= (n1^2)-(R/V)

DMuth_1J

I believe that how this works is we choose any five problems that are listed in the syllabus. He wants us to choose ones that are related to the most recent lectures. We hand them into our discussion TA, except for this week only when we turn them in Friday during the lecture.

DMuth_1J

Does higher frequency always mean shorter wavelength (and lower frequency always mean longer wavelength)? Also, when the intensity of light is increased, what exactly is being increased? I thought that changing the intensity of light altered the frequency / wavelength.

DMuth_1J

What are we expected to memorize in regard to atoms / electrons? Do we have to know the equations or the mass of an electron?

DMuth_1J

A good way to remember this that I always use is that, when writing normal numbers, you could also write 002, which is still two. But we intuitively ignore the zeros before the important digit. It applies similarly to decimals. For example, (.002) is still one significant figure.

DMuth_1J

Hello, I was working on the photoelectric effect module and was stumped by the problem that gives the velocity and the work, and asked us to calculate the energy. I'm not sure how to use the velocity or how it fits into our equations, but thought it might have something to do with wavelength. Can so...

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