CHEMISTRY COMMUNITY

AryaG_4C

ashwathinair wrote:Which complexes should we know in terms of biological significance (and which formulas should we memorize)?

I believe EDTA is also important.

AryaG_4C

KNguyen_3G wrote:I know from lectures and the course outline we need to know about cisplatin, EDTA which is hexadentate, and porphyrin which is bidentate and involved in the heme complex, and what else?

I believe porphyrin is tetradentate from what I remember during the review session!

AryaG_4C

For part (b) of this question, I understand the lewis structure has one double bonded oxygen (2 lone pairs) and 2 single bonded oxygens (3 lone pairs). Why can only the single bonded oxygens bind to a metal center? I initially guessed that each oxygen could bind to a metal because they all have lon...

AryaG_4C

Alexa Hernandez 3k wrote:The ligand names worksheet???

The worksheet is on the Chemistry Class Website under "Naming Coordination Compounds"!

AryaG_4C

Hannah Romano 4D wrote:It looks like the review sessions begin at early quantum. Does this mean that fundamentals isn't on the final?

Fundamentals is included in the review session on Friday night (7:30-10)

AryaG_4C

It would be n=4 and l=1 as it follows the s,p,d,f pattern.

AryaG_4C

They are species that provide electrons.

AryaG_4C

a. Shape is T shaped as there are two lone pairs and 3 shared.
b. Expected bond angle: 180 and less than 90

AryaG_4C

1. VSEPR: AX2E3
Linear
180 Bond angles
2. AX4
Tetrahedral
109.5
3. AX3E
Trigonal Pyramidal
less then 109.5 due to lone pair

AryaG_4C

I think a good way would be to go through all concepts and then homework problems that may seem hard/tricky and review sheets that will be provided.

AryaG_4C

The 1 isn't compulsory but I believe it depends on your preference.

AryaG_4C

The factors such as the number and location of the lone pairs and bonded pairs help determine the shape following the idea that there should be max repulsion and also following the order of repulsion.

AryaG_4C

VSEPR essentially is important as it shows us where the lone pairs should be located with respect to the central atom to ensure max repulsion and gives the 3D shape of the molecule.

AryaG_4C

I think it has to do with the fact that they should be in a position to be maximally repelled from the under lone pairs present.

AryaG_4C

We were given this information during lecture and its also in chapter 3F in the Chemistry book assigned.

AryaG_4C

What are all the factors that affect Intermolecular forces? For example, higher boiling point corresponds to greater force.

AryaG_4C

Yes and this knowledge also helps to determine the size of the angle made by the bonds.

AryaG_4C

VSEPR models takes in repulsion while determining the shape of the molecules and the subsequent angles that the bonds have. In general, repulsion strength follows the rule of:
lone-lone pair>lone-bonding pair>Bonding-Bonding pair

AryaG_4C

Sigma and pi bonds will also be included in the Test 2.

AryaG_4C

What exactly do we need to know about it for Test 2?

AryaG_4C

I believe we do need to know the different shapes (trigonal pyramid etc) and be able to recognize them. I think having a general idea of bond angles is imp to be able to comment on the relative size of the bond angles of the diff bonds.

AryaG_4C

We're not expected to know the exact bond angle, simply give an idea that it would be less than a certain value due to the repulsions acting on it.

AryaG_4C

An example of when atom positions influence the shape is for the sulfite ion (SO3)^2-. In this, there are three bonding pairs and one lone pair. Thus, although the molecular shape tetrahedral to reduce repulsion the name of the shape is trigonal pyramid.

AryaG_4C

I believe that you simply need to give an indication that it will be less than 109.5 and in case of other repulsions acting on it, you could mention that it could be lesser. For example, if its is already less than 109.5, then the lone-bonding pair interaction could also be acting on it reducing the...

AryaG_4C

For this question, why is BeBr2 not ionic?

AryaG_4C

Does anyone know any short method or trends that make it easier to know/calculate the formal charge of an atom? Like creating a double bond would help the formal charge to be more towards zero etc?

AryaG_4C

You know whether a molecule has resonance when after drawing the lewis structure you can move around the double/triple bonds or the electron pairs without changing the position of the atom. Some resonance structures may be more stable than others depending on the formal charge and may contribute mor...

AryaG_4C

I am not entirely sure if its just associated to this topic but how exactly are we supposed to know that in a compound for eg NH4Cl we have to dissociate NH4 and Cl as its a salt and then draw the specific Lewis Structures? Basically when do we know it's not a covalent i.e sharing of electrons betwe...

AryaG_4C

Yes, I believe you would use the negative energy to calculate the n value.

AryaG_4C

Usually it is put on the element thats more electronegative.

AryaG_4C

You have the frequency so using E=hv the energy can be found. Then we know its n final-n initial and n final is n=4. So, to find n initial we can plug this into (-hr/n final^2)-(-hr/n initial^2) = energy found above. Then solve for n.

AryaG_4C

In resonance, the single and double bond length is the same and is then the approx average of the two.

AryaG_4C

It is so because in the book it is h Bar which is essentially (h/2). Thus, it ends up being h/4*pi when h bar is divided by 2.

AryaG_4C

The idea of Octet Rule expansion definitely has an effect whist drawing of the Lewis Dot Structures as an element (P, S, Cl) can have more than 8 electrons shared when they are combined with another element. This is so as these elements are extremely engaged in contributing to the making of various ...

AryaG_4C

A formal charge of 0 is considered most stable and it is essentially another way to figure out how to make a lewis dot structure as you want the element that is more electronegative to have the negative charge and vice versa.

AryaG_4C

In lecture we were told that those molecules that have resonance have a bond length that is in between that of a single and double bond length. Moreover, the general rule is that single bonds are bigger than double bonds.

AryaG_4C

He mentioned that in lectures although he said it is not a part of our syllabus! It is essentially bodies that absorb/emit all frequencies therefore would be essentially invisible.

AryaG_4C

The quantum number ml is the magnetic quantum number thats useful to determine the orientation regarding the shape and can take values from -l to +l.

AryaG_4C

I think that you should essentially try and understand via the audio video lectures that are on the class website and then do the post module as well as the homework question to test yourself!

AryaG_4C

I think we can ask our TA to do that or simply just check the number of comments you have and whether there were five for each week.

AryaG_4C

They cover material relevant to the past topics studied during lectures. You can get involved in a discussion and definitely get help on any doubts you may have and you don't require to register.

AryaG_4C

Balmer series:
- release e- to n=2 from various energy levels
- in the visible light
Lyman series:
- release e- to n=1 from various energy levels
- UV Light

AryaG_4C

I think that you should use 15.999 for calculation purposes as that is more accurate and only round off numbers for the final answer.

AryaG_4C

In my understanding, the number of energy levels are infinite.

AryaG_4C

In lecture we were told that increasing the energy via increasing the no. of photons happens for light when it behaves like a particle however does the amount of energy per photon play a role?

AryaG_4C

Can someone let me know if I am right, wrong, or at least on the right track. Since light does not have only the properties of waves, only increasing the amplitude of the light won't increase the energy? Only increasing the frequency will increase the light's energy? My understanding is that this e...

AryaG_4C

During lecture, we were told that the we are to assume that the electron is outside the atom as our basis for calculation but not n=1 which is nearest to the nucleus. Why was that so?

AryaG_4C

I understood it until where the moles were calculated, but why exactly are we supposed to multiply by 1000?

AryaG_4C

What volume in ml of 18.0M $H_{2}SO_{4}$ is needed to contain 2.45g of $H_{2}SO_{4}$ ?

AryaG_4C

I feel a good way would be to go over the modules put on the chemistry website and after completing the post assessment to attempt questions from the same topic via the chemical principles book. This would strengthen your concepts and ability to answer various types of questions.
Hope it helps!

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