CHEMISTRY COMMUNITY

Alicia Beebe

Sarai Ventura 1L wrote:Yes I think it would be helpful to know the charges to save time and I think you should know the common ones.

What are the common ones?

Alicia Beebe

Can someone walk through the process for figuring out composition? Like where each part of the final answer comes from?

Alicia Beebe

I understand how to calculate hybridization, but I don't understand what it means. Can anyone help?

Alicia Beebe

I struggled with this one because I wasn't sure how to convert the work function. I just had to remember that it was in kJ/mol, and needed to be in J/ atom. This was confusing for me because it is normally just written as J. So I had to multiply it by 1000 and divide by 6.022*10^23

Alicia Beebe

My TA said that we should memorize some of the common ligands for the final, does anyone know which ones?

Alicia Beebe

From my understanding, pi bonds are easier to break, so they're the "first to go." This also makes sense along with what others were saying because each bond is at least one sigma bond, sigma bonds form first and break last. But, in each bond there can only be one sigma bond, so a double b...

Alicia Beebe

From my understanding, naming isn't part of this course. I would say it's safe to assume we have to know all of the structures he went over in class, which i believe goes up to octahedral. I'm not sure about hybridization and polarity, though.

Alicia Beebe

I noticed when doing some of the homework problems that sometimes the angles were listed as exactly 120 degrees, but sometimes it was listed as "slightly less than" 120 degrees. I'm just using 120 as an example, but what determines whether its just 120 or slightly less than?

Alicia Beebe

For four regions of electron density, it could even be angular if there were two lone pairs and two bonding pairs. I think of it as with four regions of electron density, your starting point is tetrahedral. If there's one lone pair, you "remove" it from the structure, but don't move any of...

Alicia Beebe

Can someone explain to me this naming convention? I know it has to do with bonding and lone pairs, but am confused about what it actually means and how to construct it, as well as what it's used for. Thanks!

Alicia Beebe

The way I think of it is that trigonal planar has three regions of electron density, or three "attachments" to it. Trigonal pyramidal, however, has four. If you were looking at an atom with three bonds and a lone pair, you would see that it has four "attachments" which can give y...

Alicia Beebe

In discussion last week, we were working through problems of determining molecular shape. I think I understand the concepts and process well, but got confused on the wording. It seems to me that there are two different answers for molecular shape based on if you include the lone pairs in the naming,...

Alicia Beebe

Additionally, part of the question was a comparison of two double bonds, each with two lone pairs. In this scenario, how would you discover which of the two bond lengths was longer? * Also, is it correct in thinking the lone pairs stretch out the bond length? I struggled thinking through this quest...

Alicia Beebe

I don't use the equation given at all. My way may make no sense to you, but heres a try. When looking at a lewis structure i determine formal charge by looking at two things. 1. I see how many times a line or dot is "touching the atom" in the Lewis structure, so a lone pair of 2 electrons ...

Alicia Beebe

Would this make them more reactive since they desire to fill the octet rule? or is the point that them being a radical shows they aren't reactive?

Alicia Beebe

So every ionic bond has some covalent character. The bigger difference in electronegativity will always result in more ionic character, because the one with greater electronegativity will pull on the electrons so much that they will hardly be shared at all. As far as finding electronegativity, it in...

Alicia Beebe

What I understood was that an element with higher electronegativity pulls the shared electron unequally. Highly distorted electrons are highly polarizable, which results in more covalent character. More covalent character also comes from ions causing distortion having high polarizing character. What...

Alicia Beebe

To clarify, this means that electronegativity and electron affinity are expressing the same idea, or a similar idea, but electronegativity is a relative scale whereas electron affinity is quantitative?

Alicia Beebe

Hi! Two questions 1. Can someone summarize the difference between electronegativity and electron affinity? 2. What was the rule comparing electronegativity and placement within a lewis structure? Was is that in general the highest electronegativity goes in the middle, or the lowest? Or what was the ...

Alicia Beebe

I am also confused because, if these elements disobey the octet rule, aren't there several possible ways to write the structure? how do we know which one would be correct?

Alicia Beebe

No, there is ONE way to distinguishably orient it when l=0, meaning the s orbital, so there would be one value of ml, making only one orbital. the one value of ml is that ml=0.

Alicia Beebe

One way to think about it that helped me is that ml describes the orientation of different subshells. The s-orbital is shaped like just a sphere, so there is only one distinguishable way to orient it, indicating that there is only one ml, which is true. The p- orbital is like a three-dimensional inf...

Alicia Beebe

if n=1, meaning the principle quantum number = 1, the letter you are talking about is l. l can only equal whole numbers up to the value of n-1, so if n=1, then the only l there could be is 0. When l=0, that's indicative of the s orbital. l has to be 1 to get the p orbital, 2 for the d orbital, and 3...

Alicia Beebe

Although there are ways to memorize it, i find it helpful to just think through it with the rules in mind. For example, if it was 1s, we know the principle quantum number is 1 and the subshell is s, meaning that l=0. Becuase l=0, m must also be 0. And then we know that there can be spin up or spin d...

Alicia Beebe

I'm confused about the concept of photons versus energy. are photons the energy unit and therefore the more photons present the more electrons released? or are photons different from energy?

Alicia Beebe

going off of these ideas can someone clarify me which other electrons could exist? if the given electron is n=4, l=2, m=1, ms=+1/2 there could be a n=4 l=2 ml=1 ms = -1/2? and these would be paired? and there could be a n=4 l=2 ml=-1 ms=1/2 and this would be parallel to the original? want to make su...

Alicia Beebe

l is the subshell and describes shape, also known as the angular quantum number. m is the orientation which labels different orbitals of a subshell, also known as the magnetic quantity number

Alicia Beebe

I also struggled with different periodic tables having different values present, but I just asked my TA if I could keep the periodic table from the quiz week 2 and have been using that one and it corresponds well.

Alicia Beebe

I am also very confused if it matters the way they are connected. Is it just counting up the atoms and that's it? It seemed like some where bound differently, making different structures, so I thought that would result in a different formula.

Alicia Beebe

I would like to know this as well. I am also wondering if anyone knows which formulas / values we will need to know for the test? I know some were listed on the first one, but wanted to see which would be good to memorize.

Alicia Beebe

What I did was converted the 25.13 g of Fe2O3 into moles by dividing by its molar mass (159.69) to get that .157 moles of Fe2O3 were consumed. When looking at the stoichiometric coefficients, we can see that for every 1 mole of Fe2O3, there needs to be 3 moles of CO. Thus I multiplied the .157 moles...

Alicia Beebe

What I did is found the equation, and then I found out the moles of each of the products produced, using the given masses. From that, I found the number of atoms of carbon and hydrogen that were produced by looking at the molar ratios and the definition of a mole. Once I knew the quantity (in atoms)...

Alicia Beebe

I used a different method, but wanted to see if I got the same answer. I got 1.541 mol ethanol, did anyone get the same thing or am I off track?

Alicia Beebe

What volume of a 0.2089M Kl solution contains enough KI to exactly react with the Cu(NO3)2 in 43.88 mL of a 0.3842 M solution of Cu(NO3)2? The equation is: 2Cu(NO3)2 + 4KI -> 2CuI + I2 + 4KNO3 I set up this equation based on (molarity initial)(volume initial) = (molarity final) (volume final) to get...

Alicia Beebe

No, you can balance just as you normally would. All these symbols do it keep the integrity of the equation. If these equations were applied in a real lab example, the delta indicates that heat must be added for the reaction to proceed. The idea of these equations is that they can occur in real life,...

Alicia Beebe

You would multiply by three, because you would get a more precise answer by doing so. If you multiply 2.66 by three you get 7.98, which is a lot closer to 8 than 2.66 is to 3. Overall, these normally require a judgement call, but it is safe to say (in at least every problem that I've encountered) th...

Alicia Beebe

Since there is no longer a course reader, where would one suggest to find more practice problems to prepare for the first test? The module questions are helpful, but they are different than both the homework problems and the problems received in discussion section.

CHEMISTRY COMMUNITY

Search found 37 matches

Re: Charge of ligands

Composition

Re: basics of hybridization

Re: 4b practice midterm

Ligands to Memorize for the Final

Re: Differences Between Pi and Sigma bonds

Re: Molecular Shapes On the Final

Angles between bonds

Re: Regions of e- density: Tetrahedral vs. trigonal pyramidal

Ax?e?

Re: Trigonal Planar vs Trigonal Pyramidal

Wording of Questions Regarding Molecular Shape

Re: Test 3 bond length question

Re: formal charge

Re: Radicals

Re: ionic character

Re: Polarization

Re: Electronegativity vs. Electron affinity

Electronegativity vs. Electron affinity

Re: Octet Exceptions

Re: Clarification on magnetic quantum number

Re: Clarification on magnetic quantum number

Re: Confusion about why there is no 1p, 1d, or 1f orbital? [ENDORSED]

Re: energy with s,p,d,f

Re: Test 2 final question [ENDORSED]

Re: Amount of Electrons [ENDORSED]

Re: What do l and m represent? [ENDORSED]

Re: Rounding atomic weight (general question) [ENDORSED]

Re: Test #1 Question

Re: Test 2 and Wavelengths/ Frequencies Table

Re: Review worksheet week 1: question 9 [ENDORSED]

Re: Empirical Formula

Re: Review Worksheet [ENDORSED]

Review Worksheet from Lab Week 1 Question 1 [ENDORSED]

Re: Balancing Chemical Equations

Re: Homework Question

Re: Rusty on High School Chem [ENDORSED]