CHEMISTRY COMMUNITY

Andre-1H

I hope this comparison table helps! Sigma bonds have a head on overlap compared to pi bonds which overlap sideways. Pi bonds also restrict rotation while sigma bonds allow free rotation around the bond. Could you talk about how to understand sp2 and sp3 hybridization? I'm still confused on this sub...

Andre-1H

It's always the molar mass multiplied by the subscript attached to that element and/or compound. for example (PO2)2 would require you to find the molar mass of PO2 and then multiply it by two because in whatever molecule there are two PO2 molecules bound.

Andre-1H

I think something we are expected to do is understand what the molecular formula is based on a more simple type of name. for example compounds in the form YtetraX, where that molecule would be the element Y surrounded by four X elements.

Andre-1H

Jade Corpus-Sapida 1G wrote:I would imagine from our lecture notes, that Bronsted refers to protons either being donated (acid) or accepted (base). While lewis refers to electrons.

I think bronsted comes from the name of the guy who came up with the idea. kind of like schrodinger's equation. I could be mistaken though

Andre-1H

The answer is titanium connected to 4 chlorines by a single bond. The question tells you that the molecule must be neutral (sum of formal charges is 0), which means that it is highly likely that all chlorine atoms have 3 lone pairs and one bond. 4 chlorines with 7 valence electrons and 1 titanium wi...

Andre-1H

I think about ionic and covalent character as how much they share electrons or how much they keep them to themselves. Bonds where elements share electrons more (less difference in electronegativity) have more covalent character, whereas a higher difference in electronegativity yields a bond with mor...

Andre-1H

If you're ever confused about shape I think the best way is to start by drawing the lewis structure. For N3- the lewis structure has only 2 regions of electron density and no lone pairs, so it is linear. (Using this website : https://chemstuff.co.uk/academic-work/a-level/unit-1/shapes-of-molecules/ ...

Andre-1H

What do we need to know about the properties of sigma and pi bonds? I remember in class it had something to do with rotation, and that would break the pi bond, why would the rotation then not affect the sigma bond?

Andre-1H

I'm pretty sure determining this revolves around electronegativity. For ionic bonds the covalent character can be determined by polarizing power and polarizability but even then those originate from the atom's electronegativity in the first place so I'm not too sure if there is anything but knowing ...

Andre-1H

I don't think there will be a question where there is a need to know the exact value to get the answer, just the trend is important. And we don't need to know how to calculate it.

Andre-1H

Im having trouble understanding this topic so I was wondering if anyone can explain the difference between polarizing power and polarizability and provide a quick example. Polarizing power and polarizability refer to cations and anions respectively and helps determine the covalent character of ioni...

Andre-1H

I think this is just an exercise to help understand why the one with oxygen in the middle is the correct one. The question asks to select the more likely structure based on formal charges etc. So it's likely that the lewis structure drawn with oxygen in the middle will minimize formal charges more e...

Andre-1H

I'm pretty sure the answer relates to formal charge. The correct lewis structure is the one that minimizes formal charge while at the same time maintaining the octet rule for elements that cannot break it. Using your example of oxygen, if we calculate the formal charge for an oxygen with 3 lone pair...

Andre-1H

In 3.53 the question asks us to find the formal charges of the two different lewis structures and then asks which structure has lower energy. The answer is that the lewis structure with a minimized formal charge distribution has a lower energy. Can someone explain conceptually why this is true?

Andre-1H

When you do the lewis structure for CO with 2 double bonds you end up not having enough electrons to satisfy carbon's octet. Carbon has 4 valence electrons and oxygen has 6. So we have 10 valence electrons to work with. a double bonded CO has 6 electrons left but oxygen and carbon both need 4 more e...

Andre-1H

No, I think we will just need to know general trends about how atoms interact during bonding (ionic and covalent) and how this interaction correlates to the strength of the bond.

Andre-1H

I think that just because an element has a complete octet does not make bonding impossible. You're right in the sense that it makes it a lot harder and an element like Xenon won't want to bond with anything. I looked it up and it said that when Xenon and Fluorine are heated at 400 degrees celsius, t...

Andre-1H

The question says that chlorine can exist in both positive and negative oxidation states. You're probably right in that most chlorine is in an oxidation state of -1.

Andre-1H

Even though drawing them can be painstaking, I'm pretty sure it's a solid way to figure it out. Maybe it wouldn't necessarily be the best way to do it on a test but I think getting comfortable with drawing structures is good practice to save time on tests.

Andre-1H

I'm guessing you're talking about on a test/midterm where time is an issue. An easy way to do it is to look at the question and first, determine how many sig figs your answer will have. Let's say for instance your answer has 2 sig figs. When doing a calculation, there really is no need to multiply 1...

Andre-1H

I believe oxidation state refers to the number of electrons gained or lost. So that seems to line up with the answer you gave, meaning that chlorine at most would lose 7 electrons because it has 7 valence electrons. At most chlorine is going to gain 1 electron. Both of these numbers take the element...

Andre-1H

You're correct, higher frequency corresponds to greater energy. In this case 10^-8 is smaller than10^-7 so that would correspond to a larger frequency for the photon with wavelength 1*10^-8 m, therefore greater energy.

Andre-1H

thank you!

Andre-1H

I think also that because as you go across a period there are more valence electrons, this also attracts it towards the increasing amount of protons. More negative particles on the outermost part of the atom become attracted with a stronger force to the increased amount of positive protons in the nu...

Andre-1H

So, even though we are not responsible for the elements that occupy these orbitals, could we then apply this to the next row and say that 4d is lower in energy than 5s? Or would that be the only exception for this line of thinking?

Andre-1H

A way that makes it a lot easier for me is thinking about certain orbitals as a multiple of n and p. For example you said n=2 and l =1. From class we know that when l=1 we are talking about p orbitals. n*p in this case would give us the 2p orbital. from the periodic table there are six elements that...

Andre-1H

Hello, I have a question about the concept of an ion which is a topic that has come up on our tests but I guess I don't have the best understanding of it. When calculating the molar mass of an ion would you for example (Na+) get the molar mass of sodium (periodic table) and then subtract the mass of...

Andre-1H

I think another way to think about this is from the equation E(n)= -hR/n^2 As n increases the electron has more energy which means that if an electron were to drop down to a lower level it would emit energy. This would mean an input of energy is required to elevate an electrons level.

Andre-1H

I'm pretty sure that the only way to calculate it would be if the mass of the object with that wavelength is given because otherwise with the DeBroglie equation there would be two unknown variables.

Andre-1H

Yep just to add on it makes sense that the second equation is like that because for an object like a marble its speed can change, meaning that its momentum can change, leading to the delta symbol. However, its mass is constant, and cannot change.

Andre-1H

Like everyone has said, just because there is not a given equation for energy in terms of what is given doesn't mean that you can't rearrange two equations to obtain what you want. Combine the equations E=h(frequency) and c=v (frequency)

Andre-1H

Are you getting the wrong answer or is it because a car's mass influences its wavelength to be negligible that there is confusion. The unit for velocity in the equation is m/s so you did the right thing by converting it.

Andre-1H

It definitely wouldn't be a waste of time, it could even save some time on tests/midterms. Also by memorizing wavelengths you can easily find the frequency with the speed of light equation so memorizing one is like memorizing both.

Andre-1H

C6H9Cl3 + 3AgNO3 ---> AgCl + C6H9(NO3)3 You just use the reaction and the stoichiometric coefficients to determine how many moles can be produced. So you said you found C6H9Cl3 was the limiting reactant and by doing that you did the hardest part of the problem, now you use how many moles of that to ...

Andre-1H

I'm pretty sure the zero after the decimal point is not significant. So, for example the number 0.0000023 has two sig figs. (Sourcehttp://www.rpi.edu/dept/phys/Dept ... ode12.html)

Andre-1H

There's also a part on his website along the lines of "everything you need to know about sig figs" I'd recommend that (it helped me).

Andre-1H

That equation basically comes from the fact that in a dilution the amount of moles does not change. It's just a rewritten form of C(molarity)= moles/vol. There could be other questions asking to reorganize the formula to find a different unknown. But for most dilution problems the formula you gave i...

Andre-1H

I'm pretty sure the periodic table is used 99% of the time, you would only really use 1 for hydrogen if you did not have/were not allowed to use a calculator.

Andre-1H

Hey just to add on when it gives you a mass percentage the easiest way to interpret that is to assume that there is a 100g sample of whatever you are trying to analyze. So for this example you basically just find the molar ratios using a 100g sample. Let me know if you need anything else!

Search found 39 matches