CHEMISTRY COMMUNITY

Eunice_Castro_1G

Hi! Based on his email grades should be in by Saturday. Hope this helps!

Eunice_Castro_1G

Hi! I would say to memorize them, since we will only be given the periodic table and the formula sheet on the final.

Eunice_Castro_1G

Hi! All of the questions will be multiple choice. Hope this helps!

Eunice_Castro_1G

Hi! I would also take a look at Khan Academy.

Eunice_Castro_1G

Acid rain was just a real life example of CO2 interaction. As CO2 rises, acidic rain increases. Hope this helps!

Eunice_Castro_1G

Hi! ABC... were just data collected and are not the stoichiometric point. Hope this helps!

Eunice_Castro_1G

Ka is the acid constant, basically indicating the strength of the acid, and pKa is the -log of this acid constant, the lower the pKa the more acidic. Hope this helps!

Eunice_Castro_1G

Hi! Lecture 22 goes over this. I normally draw out the lewis structure and look at the dipole moments, and decide whether they cancel. If they cancel it is non polar.

Eunice_Castro_1G

Hi! I am having the same issue :(

Eunice_Castro_1G

Mauricio Maravilla 3C wrote:Will sig figs be important on the final?

Hi! They will be included in the final since it is cumulative and they take an important part on some of the calculations. I am not sure how prominent they will be on the final, but I would recommend going over it. Hope this helps!

Eunice_Castro_1G

Why are acids with short bonds weak acids while acids with long bonds strong acids, and not the other way around? This is because a strong acid is supposed to give off a proton quite easily, if the there is a strong bond (short bonds) then the electrons and all the rest will be held tightly. Strong...

Eunice_Castro_1G

Maddie Turk Disc 2C wrote:Why can Xe hold more than 8 electrons?

This is because as I said in my last post, the d-orbital can accommodate more than 8 electrons. Hope this helps!

Eunice_Castro_1G

Hi! The octet executions include group 13, which don't often complete the octet guideline, this is because they are basically in the middle and would need 5 electrons! Starting with period 3 and below, these elements can have an extended octet due to the d orbital. Hope this helps!

Eunice_Castro_1G

Hi! So first you will discard the part of the salt that you know will act neutral, for example group one and group 2. If you are left with the anion part of the salt it is more likely that it will act as a base, and if you have the cation part of the salt left it will more likely act like an acid. H...

Eunice_Castro_1G

Thank you! I find this very helpful!

Eunice_Castro_1G

Hi! Bond strength and bond length are related, the stronger the bond length the shorter it is. So when considering bond length you are also considering the strength. But as said in the post above, we are also considering the stability of the anion, so resonance and electronegativity. Hope this helps!

Eunice_Castro_1G

Resonance structures are more stable because of the delocalization. Hope this helps!

Eunice_Castro_1G

Hi! Coordination number is the number of bonds that central atom has. Hope this helps!

Eunice_Castro_1G

Hi! I am not sure what you learned in high school about acids and bases, but you can look at it in two ways:
1.Acids-accept pair of electrons
Bases-Donate pair of electrons

2. Acids-donate protons
Bases-accept protons

Hope this helps!

Eunice_Castro_1G

Hi! So you find the charge the of the Na ion by looking at its position in the periodic table. Remember that all the elements want to reach the a stable state, which is the position of the noble gasses. Na is closer to the Neon noble gas then it is to the Argon noble gas, so to reach the position of...

Eunice_Castro_1G

Hi! I don't think we are supposed to memorize them, they are often given. Hope this helps!

Eunice_Castro_1G

Hi! Oxidation state is the charge. Hope this helps!

Eunice_Castro_1G

Hi! So the charge outside the brackets indicates the overall charge, so the the inside charges should equal 2-. Hope this helps!

Eunice_Castro_1G

I think we are expected to memorize them. Hope this helps!

Eunice_Castro_1G · Re: Homework due date Hello! It is due on Sunday at 11:59pm. Hope this helps!

Hello! It is due on Sunday at 11:59pm. Hope this helps!

Eunice_Castro_1G

Hello! So Dr.Lavelle got an oxidation number 2 for cobalt because we know NH3 is neutral, H20 is neutral, but cl has a negative charge of 1. There are 2 Cl so we know there is currently a -2 charge, however we know there is an overall charge of 0 so Co has to be 2+to get rid of the 2- charge. Hope t...

Eunice_Castro_1G

Hi! It is the ligand where you add the Bis-, Tris...etc but you still leave the greek prefixes. Hope this helps!

Eunice_Castro_1G

LDF and van der Waals forces are the same thing, and any compound can undergo LDF because of their fluctuating property. Hope this helps!

Eunice_Castro_1G

Hi! Hemoglobin is the transfer of oxygen in the blood and myoglobin is the transfer of oxygen in muscle. Like Dr.Lavelle mentioned there will be more oxygen transported in the blood since hemoglobin is made up of myoglobin.

Eunice_Castro_1G

Hi! I like to go over my notes and just do the problems from the textbook.

Eunice_Castro_1G

Hi! The shape of which you described is called angular or bent.

Eunice_Castro_1G

Lakshmi Davuluri 3K wrote:
Aliya 2J wrote:If we stacked up with 40 from before, do we need to do more to have them be from this week?

I think so. I think we need to have at least five posts per week

Hi! This is right, it is 5 points per week. So you are supposed to have a total of 40 points by the end of the week.

Eunice_Castro_1G

Hi! We will have to memorize the shapes, we will only be given the periodic table and the formula sheet.

Eunice_Castro_1G

BoparaiAdeshsurjit2I wrote:Does anybody know the grading scheme. If 50% is needed to pass how much do you need to get an A?

Hello! So there are a total of 500 points and to get an A you can only miss 5 points. Hope this helps!

Eunice_Castro_1G

Hello! Dr.Lavelle mentioned in lecture that both of these notations work. Hope this works!

Eunice_Castro_1G

Hi! So sigma and pi bonds are both covalent bonds. When there exists one single bond we know it is sigma, and when there is a double bond, one of the bonds will be sigma and the other pi. Hope this helps!

Eunice_Castro_1G

Hi! So you will just know that rotation won't happen if there is a pi bond, because as you just said pi bond when rotated will break its bond. Hope this helps!

Eunice_Castro_1G

Hello! Radicals do not last very long, because they are highly reactive. Radicals arise when a photon breaks a bond and leaves a molecule with an odd number of electrons. Hope this helps!

Eunice_Castro_1G

Hi! I am also confused on the first part of your question, but I think I can explain the second part. So because the the gap between the "regular" atomic orbital space between 2p and 2s is larger than the gap between the the hybridized and the 2p then there can be no paired electrons. Hope...

Eunice_Castro_1G

Hi! So all molecules experience LDF, since they are fluctuating. Hope this helps!

Eunice_Castro_1G

Hi! So molecules with higher boiling and melting points have stronger intermolecular forces. It takes more energy to break the bonds. Hope this helps!

Eunice_Castro_1G

Agree with last post, but I would like to add it is negative because attraction is happening (negative x negative =positive) and repulsion would be positive (positive x positive = positive or negative x negative= negative)

Eunice_Castro_1G

Hi! As professor Lavelle said you can still pass, you just need a 50% to pass. You can do it! I felt better on this midterm than the last.

Eunice_Castro_1G

I mainly focus on the textbook problems and the learning objectives.

Eunice_Castro_1G

We are not required to know the bond angles, but we are able to tell if the bond angle will be less. If there are lone pairs, it will "squish" the bond angles, making the angle smaller.

Eunice_Castro_1G

Hi! NaCl has ion-ion interaction which is stronger than dipole-dipole interactions of HCl, so it will take more heat to break NaCl. Hope this helps!

Eunice_Castro_1G

Hi! So I agree with the posts above. But I would like to clarify that that the resonance structures are already implied to have the most stable charge.

Eunice_Castro_1G

Hi! Nitrogen in fact has 5 valence electrons, but what he meant was that nitrogen will follow the octet guideline.

Eunice_Castro_1G

Hi! I don't think there are any exceptions.

Eunice_Castro_1G

Hello! I was Wondering whether all the question on the midterm are from the assigned problems, or is just some? Thank you!

Eunice_Castro_1G

Hi! I will mainly focus on the textbook problems, since they can appear in the test. But I will also review the sapling homework. All practice problems help! Hope this helps!

Eunice_Castro_1G

Hi! You can still assign a shape even if the atoms connected to the central atom are different. The shape depends on how many atoms are connected to the central atom. The fact that that the atoms are not identical only affects the angle we assign to them. Hope this helps!

Eunice_Castro_1G

Coordinate covalent bond is when one atom shares two electrons (the donor) and the accepting atom just takes them. This often occurs when the acceptor does not get the 8 electrons (octet guideline) from the bonds with the other atoms.

Eunice_Castro_1G

Dipole dipole have permanent dipole moments, while induced dipole induced dipole can only occur in a non polar reaction (e.g I^2 Cl^2...). Hope this helps!

Eunice_Castro_1G

Hello! An induced dipole induced dipole interaction only happens when there is a non polar interaction, meaning that the atoms are the same (e.g I^2, Cl^2...etc). A dipole -dipole interaction occurs when there is an unequal share of electrons (but it is not an ionic interaction). Hope this helps!

Eunice_Castro_1G

Hi! Hydrogen can only have 2 electrons, this is because it is in the first orbital 1s, and you can have two electrons in it. Hope this helps!

Eunice_Castro_1G

I would say Dipole means an unequal sharing of electrons, which would imply that partial charge exists. Hope this helps!

Eunice_Castro_1G

Hi! I would recommend drawing out the Lewis Structure. Lewis acids accept electrons and Lewis bases donate electrons. Hope this helps!

Eunice_Castro_1G

Bond lengths are sometimes also determined by size. For example, the bigger the atom, the larger the distance, so the longer the bond length. Hope this helps!

Eunice_Castro_1G

Hi! Water molecules do have a dipole moment so an interaction between water molecules are in fact dipole dipole interactions. Yet, the interaction between water molecules is big that they start to form a strong bond (hydrogen bond), although not as strong as covalent bonds. Hope this helps!

Eunice_Castro_1G

The formal charge you want to get is 0, since the molecules will be more stable in this state. So perhaps that is what simplifying formal charge may imply. Hope this helps!

Eunice_Castro_1G

Hi! If you need any sort of clarification I can help!

Eunice_Castro_1G

Hello! It is all of group 13 elements that are an exception to the octet rule. Hope this helps!

Eunice_Castro_1G

Could someone explain a bit more on why atoms with high electron affinities would be more stable with a negative formal charge and vice versa? Thanks! I can try to explain. See, if an atom has high electron affinity (meaning it wants another electron "very badly") then it is unstable with...

Eunice_Castro_1G

Wavelength should be written in meters, since it that is the correct si units. It just happens that sometimes we get an answer like with x10^-9 meters, and that is the same thing as nanometers. So, it may just be easier to refer to our answer in nanometers. And visible light is mainly all x10^-9 so ...

Eunice_Castro_1G

Hello! There are subshells past f, but we do not need to know them for this class. Hope this answers your question!

Eunice_Castro_1G

Our midterm, chemistry community, and homework points will all be release tomorrow (Thursday) afternoon. Hope this helps!

Eunice_Castro_1G

Hi! Noble gasses don't just have a low affinity, they have 0 affinity. Hope this helps!

Eunice_Castro_1G

The scores will be released on Thursday. Hope this helps!

Eunice_Castro_1G

I believe the last eight bulletin points will be tested on the second midterm. The second midterm is supposed be on week 7. Hope this helps!

Eunice_Castro_1G

I often watch my favorite shows and play with my dog.

Eunice_Castro_1G

I can confirm that's the correct password to the website.

Eunice_Castro_1G

Hello! So we take the midterm during discussion section. It will be multiple choice and must be completed in 50 min (with an extra 6 min given to us. Hope this helps!

Eunice_Castro_1G

When the problem is asking for the energy to remove it is talking about the threshold energy. Hope this helps!

Eunice_Castro_1G

Increasing intensity of light does not increase energy, it increases the photons per energy. I always remember this concept by thinking about the cross country analogy. Hope this helps!

Eunice_Castro_1G

Hi! I usually round at the end. Hope this helps!

Eunice_Castro_1G

Hi! So Professor Lavelle said that the detectable wavelength is x10^-15 or greater. Hope this helps!

Eunice_Castro_1G

Hi! Based on the email we received today, we will be able to use a scientific calculator, and we should print the periodic table before the exam to have it at hand. Hope this helps!

Eunice_Castro_1G

Hi! I am not very sure if we are expected to memorize compound names, but just to be safe I would say to memorize the common ones. Hope this helps!

Eunice_Castro_1G

Hi! Wavelengths are supposed to be measured in meters (because of SI units), but Dr. Lavelle often writes it out in nm since it is just "easier" to say it than having to write x10-^9 m every time. Hope this helps!

Eunice_Castro_1G

You will not lose points if you use the hints

Eunice_Castro_1G

Hi! Increasing the intensity of light increases the number of photons, but does not increase the energy per photons, meaning the frequency will not increase. Hope this helps!

Eunice_Castro_1G

Hi! There are different approaches to balancing an equation, but there should only be one answer. Hope this helps!

Eunice_Castro_1G

There are rules to determine how many significant figures you should be using. It will always depend on the problem. There are rules available on his website. Hope this helps!

Eunice_Castro_1G

Hi! It is possible if they are isomers, meaning they have same number of atoms but are arranged differently.

Eunice_Castro_1G

The purpose of scientific figures is to help you get a more precise answer. Hope this helps!

Eunice_Castro_1G

No, the state of matter shouldn’t affect the way you balance the chemical equations. But you should note the state of matter to get full credit.

Eunice_Castro_1G

Hi! I believe the periodic table will be given to us during tests. Hope this helps!

Eunice_Castro_1G

Hello! I think it is preferred to have stoichiometric coefficients as whole numbers, since Dr. Lavelle mentioned how to do it.

Eunice_Castro_1G

Empirical formulas are never larger than their molecular formulas since empirical formulas are the smallest ratio (simplification) of the molecular formulas. For example, imagine 5/10 being the molecular formula and its simplification would be 1/2 (suppose this is the empirical formula), the simplif...

Eunice_Castro_1G

You should use Litters because molarity's units are in fact mol.L^-1.

Search found 91 matches