CHEMISTRY COMMUNITY

Jasraj Parmar 3H

Yes they are, just like the same format as the 2 midterms.

Jasraj Parmar 3H

You have to go to your TA's office hours. I don't think you can get access to them any other way.

Jasraj Parmar 3H

It is because if you have single bonds, it would not be the most stable lewis structure.If you double bond the SE and O together, you are able to get the most stable lewis structure. I was confused at first also.

Jasraj Parmar 3H

I believe it is possible and PKa can actually be a small negative number.

Jasraj Parmar 3H

I believe it is confirmed. Material will be proportional to the amount of time that was spent on the topic in the lectures.

Jasraj Parmar 3H

Thank you! This helped a ton!

Jasraj Parmar 3H

The pH forumla is pH = - log [H3O+].

Jasraj Parmar 3H

Lewis acids are electron poor and can be positively charged. Lewis bases are electron rich and can be negatively charged.

Jasraj Parmar 3H

It feels so intense with finals coming up.

Jasraj Parmar 3H

I like what others have mentioned about using quizlet. I think it is a great tool with memorizing prefixes.

Jasraj Parmar 3H

You have to look at the shapes and see if the dipole force cancel each other out. If they cancel out each other than it is non-polar. If they don't cancel out they are polar.

Jasraj Parmar 3H

Sigma bonds are formed by the linear or overlapping of the atomic orbitals. Pi bonds are a covalent bond where the electrons connect to the nuclei of the joined atoms.

Jasraj Parmar 3H

If a molecule has greater ionic character than it has higher electronegativity. So, for NaBr or NaI, NaBr would be more ionic because it is has a higher electronegativity difference.

Jasraj Parmar 3H

This is because of lone pair electrons whose repulsions cause a bent structure. This causes the charges to be unequal throughout the molecule. If the charges had equal distribution, then it would be a nonpolar molecule. However, since it is not equally distributed it would be a polar molecule.

Jasraj Parmar 3H

Resonance is when more than one correct lewis structure can be drawn for a molecule. This can happen by rearranging single, double and triple atoms among atoms. It is possible to make one lewis structure representing all of the possible lewis structures by drawing a resonance hybrid. A resonance hyb...

Jasraj Parmar 3H

Phosphate is in period 3 so it can have an expanded octet and hold up to 18 electrons theoretically.

Jasraj Parmar 3H

Week 8 is still 5 points and you should post 5 times this week to make sure you get your points.

Jasraj Parmar 3H

Yes, elements in Period 3 can have up to 18 electrons compared to the octet rule which states up to 8 electrons per atom. The trend continues for periods 4 and below.

Jasraj Parmar 3H

A coordinate covalent bond is a bond formed between a Lewis base and a Lewis acid. A Lewis base donates electrons while a Lewis acid accepts an electron. A good example is BF3 since fluorine can not be double bonded Boron only has 6 valence electrons and it needs 8. However F- can attract to BF3 whi...

Jasraj Parmar 3H

H,He,Bi or Li don't have to follow the octet rule also if the element is in third row. The element can theoretically have a maximum of 18 electrons but its usually 10-12 electrons. The higher amount of electrons are an expanded octet.

Jasraj Parmar 3H

Dipole Dipole interactions occur when there are two polar molecules that interact with each other.

Jasraj Parmar 3H

Yes, 4s fills up before 3d. I was a little confused at first also. The trend also continues for 5s,4d and 6s,5d.

Jasraj Parmar 3H

Same, I am worried about this midterm a lot. Its good to see I am not alone which helps a bit.

Jasraj Parmar 3H

Yes, if a molecule has a permanent dipole moment, then the molecule would be considered polar covalent.

Jasraj Parmar 3H

They both follow the same trend which is that if you go diagonally across the periodic table then both will increase.

Jasraj Parmar 3H

Yes, you are right. All single bonds are sigma bonds and all double bonds are sigma and pi bonds.

Jasraj Parmar 3H

No, you don't have to worry about the F-Block. Its just the s, d and p blocks.

Jasraj Parmar 3H

Double bonds are shorter than single bonds because they have a stronger attractive force. This causes to come closer together which leads to shorter bond lengths.

Jasraj Parmar 3H

For radical stability, the order from least to greatest stability: Methyl < Primary < Secondary < Tertiary. This is due to the delocalization of the odd electrons.

Jasraj Parmar 3H

In order to find which atom to put in the center, you need to find the one that has the least electronegativity.

Jasraj Parmar 3H

Noble gases already have eight electrons in their outer shells (full octet). So, they won’t be able to attract any more electrons.

Jasraj Parmar 3H

If an atom or molecule has an unpaired valence electron, then it would be a radical. This is the same for ions also.

Jasraj Parmar 3H

Sigma bonds are stronger because they allow for electron density to be more concentrated between the two nuclei. A pi bond also has a weaker covalent bond than a sigma bond.

Jasraj Parmar 3H

There are subshells that are past f but you won’t have to worry about that for this class.

Jasraj Parmar 3H

The main difference really is ionic bonds are the transfer of electrons. While on the other hand, covalent bonds are the sharing of electrons.

Jasraj Parmar 3H

H and Hi are exceptions to the octet rule because a full shell for them is only 2 electrons which is the 1s shell. Li loses one electron because they are metals and likely to become cations they then only have 2 electrons. This makes Li an exception to the octet rule.

Jasraj Parmar 3H

Yes, De Brogile’s equation can be used for neutrons. It can also be used for protons in addition. Since you know the mass of protons and neutrons you can use the De Brogile’s equation.

Jasraj Parmar 3H

It is possible it could be. However, you only have to worry about the l = 0,1,2,3 values for this class.

Jasraj Parmar 3H

Yes, you can use your phone. You just have to have another device that has respondus.

Jasraj Parmar 3H

No, there isn't really a specific cutoff for empirical formulas. I think in most cases if you do the steps right you should be able to get a pretty good ratio. I wouldn't worry too much about it.

Jasraj Parmar 3H

Yes, having higher electron affinity correlates to electrons being able to easier accept ions. Also, they further up and more right of the periodic table you go the higher the electron affinity goes. This is because the electrons added to the energy levels are closer to nucleus which then leads to h...

Jasraj Parmar 3H

No, you can't calculate the atomic radius for one lone atom. You would need two other atoms that are close and then you just take half the distance between those two. They also have to be bonded together.

Jasraj Parmar 3H

You use standard SI units, So I would just stick to kg for the mass.

Jasraj Parmar 3H

I think you use 3.29 x 10^ 15 as the Rydberg Constant for Hz.

Jasraj Parmar 3H

The maximum number of electrons that are released would be the total amount of energy divided by the work function. The work function is the minimum amount of energy that is required to release an electron from the surface of a metal.

Jasraj Parmar 3H

I am pretty sure Dr. Lavelle said that we just need to understand the concept and not worry about the formulas . So, most likely the formulas will be provided on the exams.

Jasraj Parmar 3H

Delta E is negative because photons are being emitted which is an exothermic reaction. If photons were being absorbed then you would have an endothermic reaction. In this case Delta E would then be positive.

Jasraj Parmar 3H

I think the modules are instrumental in understanding the material. Those problems go well in-depth in the material and I think if you get those then you really understand the material. I was wondering also on more ways to study everyone has some great tips!

Jasraj Parmar 3H

You can use the De Broglie Equation to find the wavelength of any moving object. That is one the key concepts of what De Broglie Equation is used for. The equation uses mass (m) and Planck's Constant (h) and velocity (v) to find the wavelength.

Jasraj Parmar 3H

I try my best not to round too much because it will help get you more precise answers. I would use your sig figs to get your final answer.

Jasraj Parmar 3H

You can use an external device but I think it is recommended that you get a webcam. I think webcams are easier to show your work than an external device.

Jasraj Parmar 3H

Unless the problem states otherwise, I think both forms are acceptable. They just need to be the correct value. I would just make sure on the test to use the correct unit if it specifies in the problem.

Jasraj Parmar 3H

I just take the compound with the highest element and go from there. Also, you can count the amount of atoms in reactant and products and try to balance it that way. I agree with the other person who commented there are many ways but they should lead to one equation only.

Jasraj Parmar 3H

Mmol is millimole. Milli- means 1/1000th of. So, it would be 1/1000th of a mole. Also, another example of “milli” is milliliter which is one thousandth of a liter.

Jasraj Parmar 3H

I think that means that the energy of the photon must be greater than or equal the required energy to remove an electron( Threshold energy).Once the threshold energy is met, then electrons will be emitted.

Jasraj Parmar 3H

I think you just have to know that 400nm to roughly 700nm is visible radiation or visible light anything higher than 700nm would be the Infrared Radiation and anything lower than 400nm would be your Ultraviolet Radiation.

Jasraj Parmar 3H

He multiplied all of them by 3 because you can only have whole numbers when you write out your empirical formula.

Jasraj Parmar 3H

I think we are provided a periodic table for quizzes and exams. You aren’t required to memorize the periodic table only the very basic ones if anything.

Jasraj Parmar 3H

The textbook problems aren’t graded. They are highly recommended though because they will be very similar to what you will see on the exams.

Jasraj Parmar 3H

The unit is “milli” so mmol would be 1/1000th of a mole. Another example of “milli“ is millimeter which would be 1/1000th of millimeter.

Jasraj Parmar 3H

Yes, the empirical formula can be the same as the molecular formula. The molecular formula will never be less than the empirical formula. This is because the empirical formula is already the lowest possible ratio.

Jasraj Parmar 3H

You have to multiply to get a whole number if you have a fraction of atoms. For example, in the lecture, if you end up with 13/2 O2 then you must multiply the whole reaction by 2 to get a whole number. I think most likely you will have to do this on the test if you get a fraction of atoms.

Jasraj Parmar 3H

I honestly think it really doesn’t make too much of a difference. I personally use 15.999g just to be safe. However, since the difference between the numbers are extremely small. I doubt it would cause your answer to be significantly off if you used 16g instead of 15.999g.

Jasraj Parmar 3H

The moles of solute will always stay the same. If you add water that will only decrease the concentration of that solution but will not change the moles of solute. If you add the water the volume will increase also. In general, the volume and concentration( Molarity) can change but it is not possibl...

Jasraj Parmar 3H

Yes, M1V1 = M2V2 is typically used as a dilution equation. Concentration can be interchanged with Molarity to give C1V1 = C2V2.

Jasraj Parmar 3H

We cannot assume anything in Chemistry. If a problem has an equation, we should check and see if it is balanced. There will be instances where equations will not be balanced.

Jasraj Parmar 3H

No, it is not possible for empirical formulas to be greater than molecular formulas. Empirical formula is the simplest whole number ratio of atoms in a compound. On the other hand, molecular formula is exactly the whole number ratio of various types. It is possible for the molecular formula to be eq...

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