CHEMISTRY COMMUNITY

Emily_4B

Katherine Brenner 3H wrote:Does Dipole Moments indicate polarity also?

Yes if dipole moments do not cancel out then the molecule is polar

Emily_4B

It would be -1

Emily_4B

You would write the hybridization for the sigma bond and both pi bonds separately

Emily_4B

Can someone explain what cisplatin does?

Emily_4B

Both terms will be accepted on the final as they are simply different naming conventions as previously mentioned. Cyanido being the newer convention.

Emily_4B

Fiona Latifi 1B wrote:
Emily_4B wrote:would we need to know this on the final?

Yes, you should know it for the final.

Got it thanks

Emily_4B

Jorge Ramirez_4H wrote:How much points would we lose if we just didn't get the hydrogen bonding sites?

4 points

Emily_4B

Tests were handed back in discussion for those who had it Tuesday

Emily_4B

For this question, you had to be able to identify that all the single bonds had a sigma bond in it and that all the double bonds that a sigma bond and a pi bond in it. When counting the number of hydrogen bonding sites you need to include the H-bonds already present and the lone pairs on N,O, or F....

Emily_4B

All single bonds are sigma bonds and while double bonds have 1 pi bond and triple bonds have 2 pi bonds

Emily_4B

would we need to know this on the final?

Emily_4B

The step-up sessions are helpful as well as reading the textbook and doing the assigned hw problems!

Emily_4B

one or two lone pairs

Emily_4B

sarahsalama1G wrote:if something had hydrogen bonding, it would have a high boiling point correct?

Yes it’s the second strongest bond after ionic bonding

Emily_4B

sarahsalama1G wrote:What are the bond angles for T-shaped?

They have 90 and 180 degrees angles

Emily_4B

My friend who is currently taking Chem 14B and BL this quarter advised me to not take them at the same time for that reason, so I think it’s true.

Emily_4B

I find that if I’m taking too long to figure out a problem at the beginning it helps me to skip it and do an easier problem so by the time I go back to the harder question I’m more calm and ready to process it.

Emily_4B

lone pairs count towards molecular geometry not electron domain geometry. so in the case of 4 electron domains (3 bonding and one lone pair), the electron domain geometry would be tetrahedral while the molecular geometry would be trigonal pyramidal. So if asked in a question what shape a certain mo...

Emily_4B

Matt Sanruk 4F wrote:That's because you gotta convert it from kg to g

Wait bro it’s supposed to be in kg

Emily_4B

yikes thanks

Emily_4B

Matt Sanruk 4F wrote:I'm going to need to do well on those tests after that midterm!

Same, or miraculously get extra credit opportunities

Emily_4B

Does anyone know why on question 3A. The solutions use 9.109x10^-34 instead of 9.109x10^-31 as it states in the equation sheet for the mass of an electron

Emily_4B

AngieGarcia_4F wrote:
Emily_4B wrote:Do you guys know if we’ll get the midterm back or be able to look at it in office hours to review this question?

My TA went over the midterm during discussion so maybe yours will too.

That sounds really helpful, thanks!

Emily_4B

Do you guys know if we’ll get the midterm back or be able to look at it in office hours to review this question?

Emily_4B

Ionic bonds tend to be stonger than covalent bonds

Emily_4B

Many of the elements with n is greater or equal to 3 can have an expanded octet, for example, chlorine and iodine. In addition, Boron and Aluminum sometimes do not have a complete octet and instead only have 6 valence electrons as it minimizes formal charge (ie BF3). Why do Br and Al not need to ha...

Emily_4B

I would suggest the chemical bonds section because its the last thing we covered.

Emily_4B

It depends on your lecture time and last name. Go on the class website and click on midterm review sessions and rooms; it’s listed on there. I attached a screenshot of it for convenience

Emily_4B

Recall that ionic bonds form between molecules with a high difference in electronegativity, usually those with a electronegativity difference greater than 2. BaBr2 is the only molecule that primarily forms ionic bonds because the difference in electronegativity between Ba and Br is greater than 2. ...

Emily_4B

In Friday’s lecture Lavelle said that everything up until the last slide he showed that day would be on the midterm, the last slide was interactions between ions and molecules

Emily_4B

Would using the element with the lowest ionization energy be synonymous to the lowest electronegativity?

Emily_4B

we didn’t cover it so I don’t think it’ll be on the midterm

Emily_4B

I believe this is where finding the formal charges for each atom comes in and then placing the double bonds in a position that creates the lowest formal charge possible

Emily_4B

Dr.Lavelle also mentioned that resonance structures show the limitations of Lewis structures since the actual models tend to have an average of the different bond lengths!

Emily_4B

What other elements are not subject to the octet rule?

Emily_4B

I think you could do problems from either or both topics and be fine since the last topic we covered Monday was still under the Quantum world and today we started the new unit.

Emily_4B

Is there any case where the atoms lewis structure doesn’t have a full octet?

Emily_4B

Write the order of the electron configuration from increasing energy level (n=1, 2, 3, etc.). So that's why if you remember in class we put for element Sc's electron configuration the 3d shell before the 4s shell even though, if you read it based off the periodic table 3d comes after the 4s shell. ...

Emily_4B

Ali Polansky 1A wrote:Ψ means wavefunction.
the equation is E(wavefunction)= H (wavefunction)

where H= hamiltonian (double derivative)
E= energy of the electron

What does the Hamiltonian represent in terms of wavefunction?

Emily_4B

Can you post the whole question

Emily_4B

chari_maya 3B wrote:Wouldn't the total uncertainty be 10 m/s, because the uncertainty is 5.00 m/s +/- 5.0 m/s?

Do you always add the numbers to find the total uncertainty?

Emily_4B

how do you know which combinations are possible/not possible for the values?

Emily_4B

What do we need to apply psi and psi^2 to, in terms of equations?

Emily_4B

As long as the electron returns back to n=1, it is called the Lyman series (UV light) and for the Balmer series the electron returns to n=2 (visible light)

Emily_4B

Do the same steps you did for part (a) except now use the molar mass of CuSO4•5H20, which is 249.68. So you’d have to multiply (.2 M)(0.250 L)(249.68 g/mol)=12 g of CuSO4•5H20

Emily_4B

Yes, in the Lyman series an electron goes from n ≥ 2 to n = 1, while in the balmer series an electron goes from n ≥ 3 to n = 2.

Emily_4B

Energy is directly proportional to frequency according to the equation E = hν. So, the trend in increasing energy matches the trend in increasing frequency.

Emily_4B

so the constants will be given, but will the formulas that use the constants be given or do we have to memorize the different formulas?

Emily_4B

Does anyone know the energy of microwaves? Arrange the following types of photons of electromagnetic radiation in order of increasing energy: g -rays, visible light, ultraviolet radiation, microwaves, x-rays. Microwaves fall between radio waves and infrared, so from lowest to highest energy it woul...

Emily_4B

Do remember to take your own calculator though!

Emily_4B

Yes as the previous post mentioned you want to round off your number of significant figures to the same amount of sig figs that the question has :)

Emily_4B

Can't the theoretical yield also be higher than the actual yield? For example if you incorrectly weighed something or there were impurities in the final product, then the mass would increase and be greater. Yes the theoretical yield is higher than the actual yield since the theoretical yield repres...

Emily_4B

Sometimes I remember them by thinking that an (E)mpirical formula is an (E)asier simplification of the molecular formula’s ratios.

Emily_4B

The chloride is MCl, and to find the molar mass you would first find the molar mass of the M in M2O. 231.74 = 2(molar mass of M) + 16. Then by solving this you find that the molar mass of M = 107.87 g/mol. Now you can use this molar mass to find the molar mass of the chloride, MCl. The molar mass of...

Emily_4B

It might also help to examine the full equation and start with the elemnts or molecules taht appear the least amount of times on each side and work your way up. Yes I totally agree with this. One of the TA’s in the step up program recommended we balance equations this way and it’s actually been ver...

Emily_4B

Reading the textbook can sometimes intimidate me, especially when I look at certain homework problems and they incorporate elements we didn’t specifically learn about. If any of you could recommend YouTube channels or other online videos/websites you guys use to help better understand the course mat...

Emily_4B

Thank you for taking time out of your probably busy schedule to help all of us! I was wondering if you had any specific advice on time management and studying tips that you’ve learned over the years.

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