CHEMISTRY COMMUNITY

Ada Chung 1C

I've read online some conflicting things about Mg(OH)2. Some places say it is a strong base while other places say it is a weak base. Some tables include Mg(OH)2 as a strong base while other places don't include it. What would be the correct answer that Lavelle would accept?

Ada Chung 1C

Porphyrin is just the name of the ligand.

Ada Chung 1C

Coordination compounds need to be written in the right order. The right order is ligands first (in alphabetical order but not including the roman prefixes) then the metal comes after.

Ada Chung 1C

In class, we talked about how the acid is neutral or negatively charged and I was confused as to the whole Ph>Pkka and how the solution would be more Alkaline and is thus more negatively charged. I'd like to know the reasoning behind this.

Ada Chung 1C

Can someone explain why carbon monoxide is capable of binding stronger than O2 in the hemoglobin example that was talked about in Week 8's lecture?

Ada Chung 1C

In the past comments, I have seen that he does adjust the grades (the final grades) but not the tests or anything like that.

Ada Chung 1C

In order to find the concentration of H3O+ or H+ you can use the concentration formula: [H+][OH-]=10^-14. If you are given OH- concentration then you can find the H+ concentration.

Ada Chung 1C

He hasn't gone into depth on this topic yet so I feel like we would know more maybe next week. For now, I think he has mentioned strong acids like HCl as well as several weak acids. Knowing the strong acids would be important in knowing that they are completely ionized in an aqueous solution.

Ada Chung 1C

Jason Wu 1A wrote:May be off-topic, but I feel like I have used this compound before when dissociating cells and transferring them to a new culture. Now I am confused about what the purpose of EDTA is within Cell Passaging after learning that it is used to uptake metals?

^ I'm interested in knowing this too.

Ada Chung 1C

I believe that hybridization is just the mixing of orbitals so that they are all the same energy. VSEPR helps determine the geometry/shape of the molecule. I think the two are still related that in order to find the hybridization of a certain atom you would need to count the number of bonds surround...

Ada Chung 1C

Can someone explain chelates particularly in question 9.C.7: Which of the following isomers of diaminobenzene can form chelating complexes and to explain your reasoning (it gives a diagram). I'm just a little confused about what I'm supposed to be looking for in order to determine if it will form a ...

Ada Chung 1C

Ligands are electron donors that are generally attracted to the metal at the center of the complex.

Ada Chung 1C

Lone pairs can affect the bond angles because the repulsion caused by lone pairs can potentially decrease the estimated bond angle.

Ada Chung 1C

Will there be class next Wednesday before Thanksgiving?

Ada Chung 1C

In the textbook, it says "The valence electrons contribute to the electron arrangement about the central atom, but only bonded atoms are considered in the identification of the shape". I thought that the lone pairs also contributed to naming the molecular geometry.

Ada Chung 1C

I believe that is true because if the dipoles don't cancel then the molecule will be charged. In molecules where all the dipoles can cancel because of symmetry, they are considered nonpolar. An example where the dipoles cancel is CO2 which has a linear molecular shape.

Ada Chung 1C

In a trigonal bipyramidal shaped molecule, the polar bonds wouldn't cancel so this molecule would still be considered polar. If you look at the geometry you can see that it is not symmetrical in such a way that the dipole moments would cancel.

Ada Chung 1C

Dipole-dipole forces are much stronger when the molecules that are involved are close. If the molecules are closer together it will be harder to break them apart making them stronger.

Ada Chung 1C

I believe that higher electronegativity/size will cause more electron-electron repulsion thus decreasing certain bond angles.

Ada Chung 1C

Yes, you usually can tell if a molecule is polar or not depending on its geometry. If it is symmetrical than usually, the dipoles are able to cancel and will leave the overall molecule uncharged.

Ada Chung 1C

Yes, you are correct think about it in terms of the electron cloud and the polarizability of the molecule.

Ada Chung 1C

My UA said that if you draw out the 2p orbital of O and N you will see that N has 3 half-filled orbitals which are supposedly more stable than O which has 2 half-filled orbitals.

Ada Chung 1C

I don't think that Dr. Lavelle has talked about the shape of the molecule yet but I think we'll be going over that soon. But for the most part, it depends on the symmetry/shape as said above. CH4 is a tetrahedral molecule thus it is nonpolar.

Ada Chung 1C

There would not be a dipole difference between the same elements because there is zero dipole difference due to the fact that they both have the same electronegativity. However, molecules that are not diatomic like CO2 can have dipole moments despite being nonpolar.

Ada Chung 1C

I don't believe we've started covering Outline 4 (molecular shape and structure) yet so I'm assuming the homework that is due is from Outline 3 again?

Ada Chung 1C

Yes, certain polar molecules can be more polar than others depending on the electronegativity difference between the molecules. HF, for example, is a very polar molecule.

Ada Chung 1C

Will the mini dino nuggets answer key be posted as well?

Ada Chung 1C

Will diamagnetic and paramagnetic topics be covered on the midterm? It seemed to be in the textbook reading but was never mentioned in lectures.

Ada Chung 1C

The uncertainty in velocity would be 10 in this case because it is vfinal-vinitial. I'm assuming there's a typo in the solutions manual?

Ada Chung 1C

Ionic bonds can have covalent character because of their polarizability. This means that the electron cloud can be slightly distorted in a manner similar to that of a covalent bond.

Ada Chung 1C

Aside from the exceptions listed above some examples of elements that can have an expanded octet are Phosphorus, Sulfur, and Chlorine.

Ada Chung 1C

b) To answer your question for b, s orbitals are more effective in shielding because remember that s orbitals are a sphere and have a higher probability of being closer to the nucleus whereas the p orbital has a lower probability (there is a node at the center). This indicates that effective nuclear...

Ada Chung 1C

I think this is because He+ has a stronger nuclear attraction because it has a more positive nucleus making the orbital tighter and closer in He+ than in H.

Ada Chung 1C

In the lecture, Dr. Lavelle also mentioned that resonance is the blend or average of structures. It is simpler to write different versions of the Lewis structure but as mentioned by other people it is important to check the formal charge and make sure that it is as close to 0 to find the best fittin...

Ada Chung 1C

In general, we just need to know that double bonds and triple bonds are shorter than single bonds. Because the forces of double bonds and triple bonds are stronger as a result of more electrons atoms will be pulled closer together leading to shorter bond lengths. Overall, I think you wouldn't need t...

Ada Chung 1C

Does anyone know if the midterm will cover chemical bonds and molecular shape or just to chemical bonds?

Ada Chung 1C

a) p corresponds to three orbitals
b) d corresponds to five orbitals
c) s corresponds to one orbital
d) f corresponds to seven orbitals

Ada Chung 1C

Since we are still on the atomic spectra topic I'm assuming the homework due next week will still be any problems within the atomic spectra section. Please let me know if you know if that's the correct homework.

Ada Chung 1C

I'll explain my thought process of getting to the elements from the electron configuration. In these four examples, the textbook is using shorthand notation in which they are using noble gas core just to shorten up the electron configuration (otherwise you would have to write out every single orbita...

Ada Chung 1C

I know that Dr. Lavelle talked about copper, silver, and chromium having special cases in electron configurations but I was wondering if we needed to know any of the other special configurations that he did not mention like gold and palladium.

Ada Chung 1C

I don't think the positive + sign is necessary for the magnetic quantum number because if there's no positive sign it will be assumed that the number is positive. It definitely doesn't hurt to put a + sign though.

Ada Chung 1C

Here is how I would approach the problem and kind of my thought process 1. Because the problem tells you that this is in the UV spectrum you would be able to know that n1=1 (from the Lyman series) 2. Since you are given the wavelength you can use wavelength x frequency=speed of light to find the fre...

Ada Chung 1C

There are two models: In the wave model the intensity of radiation is proportional to the square of the amplitude of the wave and in the particle model intensity is proportional to the number of photons. Electrons and all matters have both particle and wavelike properties. This would be known as the...

Ada Chung 1C

Thomson found electrons through the cathode ray experiment because he was able to show that the cathode rays were negatively charged. In other words, cathode rays are basically electron beams and electrons are related to the photoelectric effect because in the photoelectric effect electrons are ejec...

Ada Chung 1C

Here's a step by step walk through of the problem I hope it helps. 1. Find total energy which is 32Wx2=64J 2. You are given wavelength is 420 nm so convert this to SI units m 3. Now using the formula E=hc/lambda plug in our wavelength and constants E=((6.626x10^-26)(3.0x10^8))/(4.2x10^-7m)= 4.7x10^-...

Ada Chung 1C

The speed of radiation is constant because that constant is the speed of light. The only two things that can be changing within the equation of wavelength x frequency=speed of light is either the wavelength or the frequency.

Ada Chung 1C

To clarify a little bit more on the Balmer series, the Balmer series of spectral emissions lines of hydrogen is the electron transitions going from a higher energy level back down to the principal quantum number of 2. To better visualize or think about this n1 (principal quantum number)=2 and n2=3,4...

Ada Chung 1C

Hi I'd love to have a pdf copy of the 7th edition if anyone can pm that to me!

Ada Chung 1C

I know that mass and atoms are conserved in a chemical reaction but I'm wondering if electrons or protons are conserved.

Ada Chung 1C

I would assume that the Homework for week 2 would be due on your discussion day next Tuesday. My discussion section is next Tuesday as well so I plan on finishing my second homework. (I have my discussion section very soon so I will double-check with my TA on that and let you know the actual answer),

Ada Chung 1C

To clarify is the fundamentals section just sections E, F, G, H, L1-2, M or should we also be reading all the sections before that?

Ada Chung 1C

Say you have the compound C10H16O and you want to find the mass percentage. I know that you need to multiply 10x12.01 to get the mass of C. In this case, would I need to use 2 sig figs or can I just use 1.201 as the mass of carbon? (I don't need help finding mass percent composition after I've found...

Ada Chung 1C

Since you already calculated the number of moles of C6H9Cl3 and we can tell that C6H9Cl3 is the limiting reactant we would need to figure out the amount of AgCl. Steps I would take: 1) Convert grams to moles of C6H9Cl3 (which you already did) 2) Figure out the limiting reaction (in our case it is C6...

Ada Chung 1C

To convert from atoms to moles you will need to use Avogadro's number (6.022x10^23). We learned that I mole contains 6.022x10^23 atoms). In order to convert moles multiply the number of moles by 6.022 x10^23 and then you should be able to find the number of atoms. If you would like to convert the nu...

Ada Chung 1C

I'm not sure if naming compounds will be apart of the exam but it is really good to know how to name compounds especially in a Chemistry course since sometimes you won't always be given the formula and vice versa. It is likely you might see a problem where you will not be given the actual formula an...

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