CHEMISTRY COMMUNITY

Emma Ide 2E

Hi! My TA told us that we're going to join a new link (I don't know if this is the same for all TAs) that is the same link all of her discussion sections are going to use. They're then going to split all the students among two breakout rooms where the TA will proctor one room and a helper will proc...

Emma Ide 2E

Stronger acids have longer, weaker bonds which can be determined if it is an acid such as H-Cl or H-F simply by looking at which bonded atom is larger, therefore creating a longer, weaker bond. For more complex acids, electronegativity needs to be accounted for to determine the pull on the bonded H ...

Emma Ide 2E

Wednesday is the last day of new content and Friday is a review.

Emma Ide 2E

Yes, just know that pH+pOH= 14, so you can rearrange the equation depending on what is given.

Emma Ide 2E

Does anyone know where the TA's post their worksheets after the review sessions?

Emma Ide 2E

It goes in alphabetical order, not including the prefix.

Emma Ide 2E

The shape can indicate if the dipoles cancel or not. Polar molecule's dipoles do not cancel.

Emma Ide 2E

In both of these cases the ligands are monodentate, meaning they only give one donor atom to the central atom, so the number of ligands, which is 4 for both of these, indicates the coordination number. However, if the ligands were bidentate, then they would give 2 donor atoms and the coordination nu...

Emma Ide 2E

You can check your grades on cycle and there are updated chemistry community points. At the end of this week, you should have 45 points.

Emma Ide 2E

I'm a little stressed but I'm hoping next week's review sessions prepare me for the final.

Emma Ide 2E

The final is cumulative and I'd assume it is in the same Respondus multiple-choice format. The time slot for the final is given when you look at your class schedule on myucla.

Emma Ide 2E

I made two linear structures, one with double bonds between the carbons and one with a single and a triple bond between the carbons, and then added single bonds for the hydrogens to the appropriate sides. For the third structure, I made a carbon ring containing two single bonds and one double bond. ...

Emma Ide 2E

The lone pairs have stronger repulsion and therefore want to stay as far away from each other as possible. Occupying the equatorial positions allows for this, as the axial positions would still require one pair to take up an equatorial position, creating a smaller angle between the lone pairs. At th...

Emma Ide 2E

Sigma bonds connect at one point, or end to end, whereas pi bonds connect side to side which creates overlap. Due to this overlap, if one side rotates and the other does not, since they aren't just fixed about one point, the rotating side will break off.

Emma Ide 2E

Any molecule with a pi bond is unable to rotate. The only way It would break is during a chemical reaction and we haven't covered any of that stuff.

Emma Ide 2E

I believe this is because when there are 3 lone pairs instead of 2 occupying the equatorial position allows for the maximum distance between the lone pairs. I think the lone pairs just go wherever they can be furthest from each other, and in this case, since there are 3 pairs It is the equatorial po...

Emma Ide 2E

For now, I believe these are the only two types of bonds we need to know unless he mentions more. As for single, double, and triple bonds, I believe it is always just a sigma bond or a sigma and pi bond(s) for double and triple bonds unless he gives us any exceptions to know in the future.

Emma Ide 2E

The repulsion of two lone pairs>lone pair-bonding pair>bonding pair-bonding pair, so the angles between bonding pairs shrink when a lone pair is introduced, as its higher repulsion pushed the bonding pairs further away from the lone pair, or closer to each other.

Emma Ide 2E

I just saw another post about this and I'm having the same problem. He said that he's making 9 additional sections and not to worry.

Emma Ide 2E

Hi, I'm confused about when an atom can have an expanded valence shell. I was adding up the number of valence electrons and then drawing a Lewis structure, but I had 2 electrons left over and was wondering if this was a case of expanded valence?

Emma Ide 2E

You are just redrawing the molecule in each possible different structure. Start by moving around different atoms and adding or taking away double bonds and exchanging their places, as long as you keep the same amount of single and double bonds as before. As long as all the atoms are there and the mo...

Emma Ide 2E

Hi, I'm trying to draw the Lewis structure for CO3 2- but I keep getting it wrong. Which atoms in the structure hold the negative charge?

Emma Ide 2E

London interactions are always present because electrons are always fluctuating, even in a neutrally charged molecule, there will still be a little bit of electron repulsion when two molecules are near each other.

Emma Ide 2E

Hi, I also was unable to take AP Chemistry and most of the topics are completely new or I just have no recollection of learning some of the topics, but I would recommend the organic chemistry tutor on youtube, he explains everything in much simpler terms.

Emma Ide 2E

I believe Lavelle let everyone from the waitlist into 14A, so I think as long as you at least get a waitlist spot you will be okay. Also, with the asynchronous format, more students are probably given a spot in the class.

Emma Ide 2E

Since the d-block is always 1 "n" value behind the "n" value for the s and p blocks in an electron configuration, once you get to elements in the s block of the p block that surrounds each d block, you only count the electrons coming from the s and p orbitals and disregard the d ...

Emma Ide 2E

So far, we do not need to memorize them yet. In the lecture, he said he had looked them up when he gave us the values, so I think we will either be given the lengths or later be told to memorize them.

Emma Ide 2E

I think partial credit can be given on those certain questions that had two parts and two answers that were selected under the same letter choice. As far as the other ones with only one part, I'm not sure if partial credit can be given on those.

Emma Ide 2E

Hydrogen is an exception to the octet rule where it can only have 2 valence electrons, or up to the 1s state, filled.

Emma Ide 2E

You can determine if something is a radical by drawing out the Lewis structure and looking for an unpaired electron. Radicals are very unstable and usually result from a more stable molecule's bond being broken, and each half of the newly made molecules taking one electron from the previous bond.

Emma Ide 2E

As long as you now up to Wednesday's lecture and the first part of section 1D in the book you should be good.

Emma Ide 2E

yes, you can return to previous questions and review your choices before submitting the test.

Emma Ide 2E

The midterm is during your assigned discussion time. It is through lockdown browser, but we will need to be on zoom with our discussion group as well. Also, it is about 50 minutes so probably 10-15 questions

Emma Ide 2E

3.289x10^15 is the only value that we will need to use for the midterm. This is in Hz or s^-1, which works for all the calculations we are doing right now.

Emma Ide 2E

regular v is velocity, and the 'fancy' v is for frequency. when I write the v for the frequency I just make it have a tail at the beginning and end to try and make it stand out

Emma Ide 2E

DeBroglie's equation can be rearranged in many ways to find other values.
wavelength=h/p
p= mv and
E=pc, so
pc=h(c/wavelength)
which gives the wavelength equation
these equations can all be derived from each other

Emma Ide 2E

Einstein's equation represents the total energy of an object and uses c, the constant for the speed of light, whereas kinetic energy refers to something in motion.

Emma Ide 2E

I thought we could only write on the two papers we are supposed to print out, but I'm sure each TA has their own policy.

Emma Ide 2E

No, not unless specified in the question.

Emma Ide 2E

Hi, can anyone help me with the wavelength portion of #6. I think I've used the equation correctly but am not completely sure.

Emma Ide 2E

No, you can use hints as well as multiple attempts I believe, as long as you get the correct answer in the end.

Emma Ide 2E

Yes I agree we need music!!

Emma Ide 2E

I just got to the following problem in the Sapling work: When a metal was exposed to photons at a frequency of 1.46×1015 s−1, electrons were emitted with a maximum kinetic energy of 4.00×10−19 J. Calculate the work function, Φ, of this metal. I understand the E=hv and to use Plank's constant, but I ...

Emma Ide 2E

The frequency and wavelength are what has to be increased since photons and electrons have a 1:1 ratio. If the frequency is not high enough to release electrons, no intensity at that frequency will ever work, therefore it is the frequeuncy that must be changed.

Emma Ide 2E

It statds for millimole. 1 mmol=0.001 mol

Emma Ide 2E

Start by covering the grams to moles, and then take the element mass/ molar mass of the compound to find the molar ratio.

Emma Ide 2E

Mine was a little bit back-ordered but finally came. I have the free trial right now but I'm not sure where to put the code to get the online book.

Emma Ide 2E

First, covert the CuNO3 to moles, and then use the formula M=moles/L. Use the given amount of M on the problem and plug that in (0.590 M) and plug in the value of moles calculated previously. Then, rearrange the equation as to solve for liters. Last, covert liters to milliliters by moving the devima...

Emma Ide 2E

I ended up with the same answer but never got 72.1 g/mol for 2 butanone and am not sure where everyone is getting that calculation? Is that just from getting the molecular formula and then determining the molar mass?

Emma Ide 2E

I just had to look up the molar mass of 2 butanone and use m=dv because I also could not figure out how to calculate it.

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