CHEMISTRY COMMUNITY

Kendall 3H

I think we just need to know that its the ligand that finds with fe to make a heme complex and that it is tetradenate.

Kendall 3H

Yeah, if you memorize the strong acids you can assume all the other ones are weak acids.

Kendall 3H

I think Linden said in the review session that we can just write sp2

Kendall 3H

yes, I think so.
For en I think we should also know the formula which is NH2CH2CH2NH2

Kendall 3H

yes, for conjugate acids, add an H+ and for conjugate bases remove and H+

Kendall 3H

yes, for conjugate acids, add an H+ and for conjugate bases remove and H+

Kendall 3H

I think you are suppose to individually label the two bonds in the double bond, one as sigma and one as pi, rather than labeling them both at pi +sigma.

Kendall 3H

hexacyanoferrate(II) ion

hexa-cyano because cyano is the name of the ligand CN-
ferrate because this is the name of Fe with -ate added to the end to indicate that the entire ion is negative

Kendall 3H

I can confirm that the final is cumulative; however, I think it will focus more on the topics we have not been tested on yet.

Kendall 3H

aquapentacyanocolbaltate(III) ion

aqua because it is the name of H2O
penta-cyano because cyan is the same of CN- and there are 5 of them
cobaltate (III) because cobalt is the name of Co and it is a negative ion so you must add an -ate to the end of the metal

Kendall 3H

en means bidentate; edta means hexadentate.

Kendall 3H

They are used if the ligand you are naming already has a name with di-, tri-, tetra-, tetra-

Kendall 3H

I believe week 9 homework can be done on anything covered after the week 8 test we took.

Kendall 3H

sigma and pi bonds do not effect the lewis structure; however, they do effect how the molecule is shaped and how its shape can change because sigma bonds allow for more rotations and movement of the molecules whereas pi bonds do not allow for this full range of motion.

Kendall 3H

hybridization gives an explanation or at least helps to explain a molecules structure when the valance bond theory fails to predict the structure correctly.

Kendall 3H

All single bonds are sigma bonds. All double bonds have one pi bond and one sigma bond. All triple bonds have one sigma bond and two pi bonds and so on. Pi bonds do not allow the molecule to rotate as much as sigma bonds do.

Kendall 3H

I believe it is only dipole-dipole, london forces and hydrogen bonding because we have not had a lecture about dispersion and induced dipole yet; but, if lecture this Monday covers these topics and we may have to know it for the test. I would just make sure to know everything covered in lecture up t...

Kendall 3H

Xeon and other noble gases with 8 electrons in their valence shells can still form covalent bonds because of their expanded octet.

Kendall 3H

if there are two central atoms, you treat each central atom as its own thing

Kendall 3H

When drawing the Lewis Dot structures I think it is important to make sure you have placed the correct amount of double bonds and single bonds and lone pairs around all of the atoms; however, I don't think it is important to make sure your drawing is depicting the correct angles of the bonds because...

Kendall 3H

I think it will be around the same length at test #1 and it is worth 50 points

Kendall 3H

Yes, I can confirm hearing that we will get our midterms back on Wednesday but am not sure if this means we just get just the grade of our midterm or if we get our actual midterm. It would make the most sense to me if we just got our grades on Wednesday and then were returned the hard copy of our mi...

Kendall 3H

I am also confused on this concept and would love if anyone could help.

Kendall 3H

I am sure Lavelle and our TA's will cover this in class next week; however, as far as I know, we will get our midterms back before the final and be able to study them without a tutor.

Kendall 3H

I am not sure if we are going to have to do this for the upcoming test. I think it is best to email your TA and ask them but I also think doing the homework problems is the best way to study so if you have to calculate how polarizing an atom is using electronegativity in any of the homework problems...

Kendall 3H

Its all just based on attraction. They are not actually sharing electrons, it is just that they are attracted to each other because of their partial negative and partial positive charges.

Kendall 3H

If it is possible, we have not learned it. However, it is easy to infer the relative strength of the bond through the length of the bond. Short bonds are stronger than long bonds.

Kendall 3H

If it was never mentioned in lecture and there were no practice problems assigned for it, I am pretty sure we do not need to know it for the midterm.

Kendall 3H

Covalent molecules share electrons, this is shown by a line in between the atoms. Ionic molecules do not share electrons.

Kendall 3H

I think ions on their own generally are not bracketed, such as Cl-; however, ionic compounds are bracketed. So, when there are multiple atoms that make up a molecule that has a charge all together, there should be a bracket to show that it is the entire molecule that is charged, not just one atom in...

Kendall 3H

Yes, I agree, there is unfortunately no "formula" for knowing which values come first and second in the equation. You must just read the question carefully. Good Luck!

Kendall 3H

I agree with the earlier answers. I believe the main reason and the reason expressed most to us in Lecture was that the structure with 2 double bonds has a formal charger closer to 0 than the structure with 4 single bonds. When drawing Lewis Structures, you always want to option with the formal char...

Kendall 3H

When a molecule has resonance it means its structure is always switching or changing. It doesn't always have to be 3 shapes or bond lengths that it switches between; it can be 2 or 4 ect. And it is not that 3 different structures exist of the molecule, but rather that the molecule is constantly swit...

Kendall 3H

The d subshell of an atom has 5 orbital and can therefore fit 10 electrons, meaning there can be 10 valence electrons rather than only 8.

Kendall 3H

Ionization energy is defined as the minimum amount of energy required to remove the most loosely bound electron from an atom or molecule in gas state. The tighter a molecules radius, the harder to remove an electron from it. Thats how I like to think of it. So as atomic radius increases, ionization ...

Kendall 3H

Yes, that is one way to think about it. Electrons are constantly changing which atoms they are being shared between. It is important to remember that electrons are always moving, they are not stationary.

Kendall 3H

I can also confirm that week 4's homework is suppose to be from the quantum world section and therefore you can pick any of the problems from the quantum world section that you have not done for another homework yet.

Kendall 3H

All you have to do for this problem is use the equation "wavelength= h/ (mass x velocity)" You are trying to find the wavelength and you already have h and velocity and all you have to do is look up the mass of a proton and a neutron. The masses are very similar. Once you calculate the wav...

Kendall 3H

Thank you, this was very helpful!

Kendall 3H

The first step is to convert the energy units from keV to Joules. - 140x10^3 eV x (1.6022 x10^19 joules/ 1 eV) = 2.2513 x 10^-14 Joules Next you can use the formula wavelength= hc/E to find the wavelength - wavelength= (6.626x10^-34 X 2.9x10^8)/ (2.2513x10^-14) which equals 8.82 x 10^-12m or 8.82pm

Kendall 3H

First, you must recognize that the ultraviolet spectrum of atomic hydrogen is the lyman series and its n1 = 1. Then you use the equation v=c/lambda to calculate v. (v= 2.998 *10^8/ 102.6 * 10^8) Now, we can use the Rydberg equation to solve for n2. After plugging in all the numbers, you will get n2=3.

Kendall 3H

First, you must recognize that the ultraviolet spectrum of atomic hydrogen is the lyman series and its n1 = 1. Then you use the equation v=c/lambda to calculate v. (v= 2.998 *10^8/ 102.6 * 10^8) Now, we can use the Rydberg equation to solve for n2. After plugging in all the numbers, you will get n2=3.

Kendall 3H

I have heard from multiple sources the deadline for posting on chemistry community is Sunday! So you have all weekend to post as well rather than having to post on Friday.

Kendall 3H

I recommend doing all the homework problems and attempting to work them out on your own, then visiting a TA's office hours where you can ask specific questions you had on the homework. I think the more specific your questions are, the better off you are to succeed.

Kendall 3H

I was informed that the better you show your work on homework and test equations, the more points a TA can possibly give you on a problem you didn't get the final correct answer. If your work is very clear, they can see where you made your mistake and hopefully give you credit for the parts you did ...

Kendall 3H

You can use DeBroglie's equation to find the wavelength of anything but light because light does not have mass.

Kendall 3H

Thank you so much! I was very confused on this question and you explained it so well. I now see that you must first discover which reactant is the limiting reactant and then the problem becomes much more simple.

Kendall 3H

32,000,000 has two sig figs. However, if there were to be a decimal point placed at the end of the number (ex/ 32,000,000.) then there would be 8 sig figs 0.3200 has 4 sig figs because the leading zero is not significant. 3.0200 has 5 sig figs. any time there is a trailing zero of final zero after a...

Kendall 3H

Yes, when writing chemical formulas you are suppose to include all the states of matter!

Kendall 3H

A formula unit can be thought of as the empirical formula for an ionic compound. For example, NaCL is the formula unit for sodium chloride.

Kendall 3H

The limiting reactant is not necessary the reactant with the least amount of moles, but it could be. When thinking about limiting reactant problems, it has always helped me to compare it to baking cookies. For example, to make one batch of cookies, you need 1 cup of butter and 3 cups of flour. Now i...

Kendall 3H

I agree with what everyone else has answered. Sig figs should only be applied to your final answer, this way your final answer can be the most accurate. If you were to apply sig figs to every calculation, you would be doing a lot of unnecessary rounding that could change the final answer pretty sign...

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