CHEMISTRY COMMUNITY

Reagan Smith 1H

We are given a sheet that has most of the equations we need to know for the test. I've attached this sheet below.

Reagan Smith 1H

I do not think it is the same thing because hydrogen bonding is an intermolecular force, whereas with acids and bases, the molecule is changing and hydrogen is moved to a different molecule.

Reagan Smith 1H

You just need to add up all of the charges (not including the metal) and then, find out what value needs to be added to get to the total charge of the compound. That value (almost always positive) will be the roman numeral you use.

Reagan Smith 1H

I would assume Bronsted-Lowry or Lewis because they are just expanded definitions of the Arrhenius definition. We have also extensively covered Bronsted-Lowry and Lewis and have not spoken of Arrhenius as much in lectures.

Reagan Smith 1H

As stated by others, hydrogen bonding can only occur with N, O, and F. The hydrogen that is going to bond must bond to one of those three atoms AND must already be bonded to either N, O, or F. Also, hydrogen will never be the central atom so you don't have to worry about that coming up:)

Reagan Smith 1H

I am not 100% sure but I would guess that the stuff we have recently covered will be more prevalent on the final since we have been tested on the other stuff already, but I would still strongly recommend studying all of the material in case some curveballs are thrown. I would ask your TA for a more ...

Reagan Smith 1H

It is usually Sunday at midnight so I am pretty sure week 10 is no exception. We should have 50 since we have 5 due per week over 10 weeks

Reagan Smith 1H

What are the indicators of a strong acid/base versus a weak acid/base?

Reagan Smith 1H

Yes, every single bond is immediately a sigma bond, but there are also sigma bonds in double and triple bonds.

Reagan Smith 1H

Everything we have covered in the lectures up to this point and the stuff up until Wednesday is fair game to my understanding! All the homework problems are fair questions to be asked and such.

Reagan Smith 1H

What are some examples of species that can replace H2O ligands to make coordination compounds, and how do you identify which ones will be able to replace it?

Reagan Smith 1H

Why is it uncommon for coordination compounds to be negatively charged?

Reagan Smith 1H

A coordinate covalent bond is when one of the atoms provides both electrons for the bond.

Reagan Smith 1H

What is the difference between Lewis and Bronsted acids and bases?

Reagan Smith 1H

Yes it is "about" 90 and 120, so if you want to be more precise you can say "slightly less than 90" or "slightly less than 120".

Reagan Smith 1H

What are the differences between molecular geometry and molecular shape?

Reagan Smith 1H

It will cover everything from after the midterm to the material we just learned on Friday, and they will test on shapes so my TA highly recommended making flashcards to go through and make sure you can determine all of the shapes we have learned.

Reagan Smith 1H

If the dipoles of two atoms are pointing in the same direction (such as the hydrogens in water) the dipoles do not cancel out and therefore water is polar, but if two vectors do cancel, the molecule is nonpolar.

Reagan Smith 1H

How can you tell which kind of dipole interaction is going on? Like dipole-dipole, induced dipole-induced dipole, etc?

Reagan Smith 1H

Yes, I believe that lone pairs of electrons are considered regions of electron density since they influence the molecular shape. Please see the attached image. Thank you so much! Do you think we are going to have to know all of the shapes? I think we are supposed to know all of the shapes we have c...

Reagan Smith 1H

I don't know which one is "more important" per se, but Dr. Lavelle pointed out that while shape impacts the difference in boiling/melting points, the number of electrons impacts it more drastically.

Reagan Smith 1H

You put the negative formal charge on the more electronegative atom.

Reagan Smith 1H

The magnetic quantum number can be determined by the angular momentum quantum number. m_l can be from -l to l.
E.g. If l=2, m_l can be -2,-1,0,1,2.

Reagan Smith 1H

It decreases across a period because the electrons are in the same orbital across a period but the number of protons increases across a period, so the pull from the positive nucleus on the negative electrons pulls the electrons closer, decreasing radius.

Reagan Smith 1H

What does it mean for dipoles to fluctuate due to fluctuating electrons?

Reagan Smith 1H

Since you were provided the mass of the compound, I think it was riboflavin, and you had the mass of each of the products, H 2 O, CO 2 , and N 2 , plus you had the balanced chemical equation , you could solve for the number of moles of C in CO 2 using a conversion factor of 1 mol C per one mol CO 2 ...

Reagan Smith 1H

No, increasing frequency of the light does not change the number of electrons ejected from a metal surface. Once the minimum frequency required to eject an electron is met, other electrons will be ejected as long as the frequency stays at that threshold level or above it. In order to eject more elec...

Reagan Smith 1H

How does dispersion explain why the three hydrocarbons in the picture in the lecture today (pentane, pentadecane, octadecane) all had different viscosities? I understand that they all have a different number of carbons but how does that play a role in dispersion?

Reagan Smith 1H

Dr. Lavelle said that Induced dipole-induced dipole, London, Dispersion, and Van de Waals are all interchangeable but also said they have some differences. What are the differences and why can we call them interchangeable?

Reagan Smith 1H

What does the Bohr Frequency condition explain or prove?

Reagan Smith 1H

Using lines helps to show that there is a covalent bond because it represents the sharing of electrons while dots represent lone pairs of electrons in covalent bonds. In ionic bonds, you do not use lines because there is no sharing of electrons.

Reagan Smith 1H

In his example of resonance in benzene, Dr. Lavelle drew a resonance structure and labeled the length of the double bond between two carbons as 1.34Å and the length of the single bond between two carbons as 1.54Å. Then he went on to say that experimentally observed C-C bond lengths all equal 1.39Å. ...

Reagan Smith 1H

Electron shielding is just the concept that electrons closer to the nucleus act as a shield to those further from the nucleus, making the outermost electrons have less of a pull toward the positive nucleus because the magnetic pull is basically being blocked by the closer electrons.

Reagan Smith 1H

Lewis structures for covalent bonding use lines to represent the sharing of electrons. Lewis structures for ionic bonding do not use lines because electrons are either lost or gained, not shared, so the dots (aka electrons) are moved from one element to the other to represent bonds, and brackets are...

Reagan Smith 1H

How do you determine which resonance structure is the most stable?

Reagan Smith 1H

The h with the dash through the stem is planck's constant divided by 2 times pi, which is equal to h/2π

Reagan Smith 1H

It is not that it necessarily affects the behavior of the electron, but it is to even out the magnetic field created by the positive nucleus with the negative electrons. If electrons are in the same orbital, the spins must be opposite. If they are in different orbitals, they must be parallel, theref...

Reagan Smith 1H

Does every single thing have both wave-like and particle-like properties? Or do only things that are quantized have wave-like properties?

Reagan Smith 1H

If you are talking about work function and threshold energy rather than threshold frequency, they are virtually the same thing, nearly interchangeable. Threshold energy is the minimum amount of energy needed to eject an electron from a metal surface, and that is denoted by the work function.

Reagan Smith 1H

I believe both ways will be sufficient in the class but to find out what element you use to write the shorthand version, you use the noble gas (the elements in the rightmost columns on the periodic table) that is in the row above the element you are writing the configuration for.

Reagan Smith 1H

From what Dr. Lavelle described on Wednesday, the reference point for the energy of an electron is 0 because we assume it is not interacting with anything. The negative energy of the electron represents that an electron bound to an atom has a lower energy than that of a "free" electron, on...

Reagan Smith 1H

Today in the lecture we were told that an electron is described as a circular standing wave around the nucleus. How does this describe why electrons have quantized energy states in atoms? Dr. Lavelle said it was from the line spectra but I do not understand how this is modeled.

Reagan Smith 1H

Finding the limiting reactant allows you to find out how much product you will be able to make because the limiting reactant will run out the fastest, determining how much product is made. The next step would generally to find out how much of the product can be produced based on how much of the limi...

Reagan Smith 1H

Is it always true that light with shorter wavelengths have higher energy? And why would that be?

Reagan Smith 1H

Threshold energy, also called work function, is the energy needed to remove an electron from a metal surface using a light.

Reagan Smith 1H

If there is a problem that includes addition/subtraction AND multiplication/division, which sig fig rule is supposed to be followed since there are different rules?

Reagan Smith 1H

You should interpret that as 1 Mg and 6 N since the parentheses do not surround the Mg at all

Reagan Smith 1H

If you are given the substance you should be able to figure out the molar mass by using the periodic table. You just need to figure out how many of each element you have so that you can multiply the molar mass of one atom of that element by the total number in the formula and add it all together for...

Reagan Smith 1H

The textbook definitely has some valuable information that goes in depth on all of the topics covered so I think it is definitely worth it to read the book and view the examples. The examples are super helpful.

Reagan Smith 1H

I think you are supposed to do the sig figs only at the end so that your rounding doesn't get messed up but if you want to be super sure Dr. Lavelle has a Sig Fig review link on his 14A website

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