CHEMISTRY COMMUNITY

Mario Reyes 1C

On the homework problem 6.1 d) hydrogen bonding was not an answer. Why wouldn't SO2 be able to form hydrogen bonds, even though it has an oxygen with an available lone pair?

Mario Reyes 1C

Is it safe to say that London dispersion forces are present in every molecule? Are these forces within the molecule, or between neighboring molecules?

Mario Reyes 1C

Does it matter which way you write a hybridization with 5 regions of electron density? Is either way of writing it correct?

Mario Reyes 1C

Professor Lavelle stressed that the number of bonds equals the coordination number, but what makes the coordination number significant?

Mario Reyes 1C

I am a little confused on what a chelate is. Can someone explain?

Mario Reyes 1C

Why is I3- linear and not bent? Would the 3 lone pairs on the central atom not cause the molecule to have a bent shape?

Mario Reyes 1C

I understand that a sigma bond correlates to a single bond, and a double bond contains one sigma and one pi bond, but why is this?

Mario Reyes 1C

Lone pairs have the greatest repulsion strength because they occupy the most volume, but how do they occupy more volume than a bonding pair?

Mario Reyes 1C

When we finish completing a lewis structure and find that the formal charges of all atoms are not 0 in a neutral molecule (even though all the charges add up to 0), should we always try to make something a double/triple bond and try to make all the formal charges zero. It seems like a very tedious p...

Mario Reyes 1C

Chem_Mod wrote:H only has 1 bond and always you have formal charge of 0 for this case.

What about when making chemical formulas for compounds. Is formal charge different from expected charges?

Mario Reyes 1C

This may have a simple answer, but why don't we find the formal charge of hydrogen in molecules?

Mario Reyes 1C

Hydrogen can either have a charge of positive or negative 1 but since Aluminum already assumes the positive charge, you use the Hydrogen charge of 1- to construct your formula :) Thank you! Do you know why it can be +1 or -1? I feel it is because it can add 1 electron to fill its outermost shell, b...

Mario Reyes 1C

I thought you put the molecule with the lowest electronegativity in the center, are ionization energy and electronegativity the same thing? My TA also said to put the least electronegative in the center, but professor Lavelle said in lecture to put the lowest ionization energy in the center. I'm no...

Mario Reyes 1C

Using periodic trends this is true, but from what I remember those are only general trends and there are exceptions. Nitrogen has a half full shell which makes it more stable than Oxygen. This results in a slightly higher ionization energy for Nitrogen, because the Nitrogen wants to keep it's half f...

Mario Reyes 1C

We actually choose the atom with the lowest ionization energy for the central atom. Even with that, part c) is still confusing since O has a lower ionization energy than N does. Anybody understand why?

Mario Reyes 1C

When writing lewis structures we put the atom with the lowest ionization energy in the center. For 3.33, part c asks for ONF. The answer shows that N is in the center, but doesn't O have a lower ionization energy? Can someone explain this.

Mario Reyes 1C

On the basis of the expected charges on the monatomic ions, give the chemical formula of each of the following compounds: (c) aluminum hydride.

Al has a 3+ charge, and I think Hydride is referring to Hydrogen. I am confused on what charge Hydrogen would have.

Mario Reyes 1C

In my notes I have both these examples with H-F H-F for dipole-dipole and H-Cl N-N(triple bond) for dipole-induced dipole. What is the difference between these two?

Mario Reyes 1C

In class Professor Lavelle said these are all similar, so is there really no difference to these forces besides the name?

Mario Reyes 1C

In regards to the example of CH4 and CCl4, CCl4 has a higher boiling point. This is because it has more electrons and is more polarizable, so does this mean being more polarizable means being stronger? Also, F2 and Cl2 being gases at room temp, while Br2 is a liquid and I2 is a solid. Does this foll...

Mario Reyes 1C

Also, if you do draw all resonance structures be sure to include the double headed arrow between each of them. Maybe it's not that big of a deal but he explicitly mentioned that in class.

Mario Reyes 1C

I'm pretty sure it depends on which has a lower formal charge. This may also have to deal with vsepr which we haven't got to yet.

Mario Reyes 1C

Be sure to skip the transition metals when trying to count the number of valence electrons from left to right.

Mario Reyes 1C

Using the trends it would seem like Sulfur would have a larger ionization energy, but just like oxygen and nitrogen, the phosphorus is half filled. Does this mean Phosphorus has a larger ionization energy?

Mario Reyes 1C

When drawing a lewis structure, why do we choose the atom with the lowest ionization energy as the central atom?

Mario Reyes 1C

I'm confused by the reasoning. I thought electron affinity was dealing with adding electrons, not taking them away.

Mario Reyes 1C

I understand why Chromium and Copper are exceptions using the symmetry argument. However, why isn't Vanadium an exception as well? The configuration for Vanadium is [Ar]3d^3 4s^2. Why don't the 2 electrons from 4s go to 3d to fill the d orbital?

Mario Reyes 1C

When writing electron configurations where you need to include the f block, why is the principal quantum number 2 behind the row. For example, for Tungsten the electron configuration is [Xe]4f^14 5d^4 6s^2. I understand the d block is 1 less, but why is the f block 2 less?

Mario Reyes 1C

From what I know ground state means the electron configuration follows the Pauli Exclusion Principle and the Hunds Rule. Is there anything else to this?

Mario Reyes 1C

l CAN equal 0, 1, 2 ,3 ,and 4. However, this doesn't mean that l will equal all of those values. In this case they tell us l=2 which indicates that electrons are in the p orbital.

Mario Reyes 1C

When using short hand, when can you only use preceding inner gases? Why can't you use any other element before it?

Mario Reyes 1C

When saying two electrons spin in opposite directions, what is that really saying?

Mario Reyes 1C

If I heard correctly in class, the 4s orbital comes before 3d only for elements with 20 electrons or less. Can somebody explain why?

Mario Reyes 1C

Maya Khoury wrote:I attached a picture below of me trying to find the speed for this problem but for some reason i always end up with a ridiculously large number. Can someone tell me what I'm doing wrong? I'm sure it's a stupid mistake lol

thank you !

The denominator should be 10^-39, not 10^-49

Mario Reyes 1C

So rearranged, the equation for velocity would be plancks constant / (wavelength)(mass) correct? I used this equation for #34 solving for speed and did not get the correct answer, which was the reason I was unsure if speed and velocity were the same.

Mario Reyes 1C

I do not understand how to calculate speed using the De Broglie equation? Is it the same as calculating the velocity? If so, how do you calculate the velocity?

Mario Reyes 1C

Since it is Efinal- Einitial, shouldn't it be E4-Ex?

Also, I am confused on these steps. How did you get -6.06x10^-20?

Ex = (-hr)/x^2 = -6.06 X 10^-20

x^2 = 35.9

x = n = 6

Mario Reyes 1C

The question asks 'An excited hydrogen atom emits light with a frequency of 1.14 x 10^14 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?' A. n = 5 B. n = 6 C. n = 4 D. n = 7 I am not sure how to approach this problem. Would we have to plug in every quantum...

Mario Reyes 1C

To add on to this, does light intensity matter for the photoelectric effect? It does matter in terms of how many electrons are emitted. If the energy of the photon is above the threshold, then increasing the intensity would cause more electrons to be emitted since intensity can be thought of as num...

Mario Reyes 1C

If you are given the energy of the photon and the excess energy, you can solve for the threshold energy by adding them together.

Mario Reyes 1C

If we used the wave model increasing the intensity of the light should eject electrons from the metal surface, because increasing intensity of the light means increasing the energy since that increases the amplitude of the wave. However, this was not the case and electrons were not ejected even when...

Mario Reyes 1C

I know short wavelengths (high frequency) have more energy than longer wavelengths, but I really don't know why. I partially understand why using the E=hc/lambda equation, but I do not understand the logic behind it.

Mario Reyes 1C

I typically see the textbook use "mols" but I'm sure either way works. As long as you don't leave it as "M" which is molarity, you're fine.

Mario Reyes 1C

I think I remember in class professor Lavelle saying that he didn't expect us to know the names of complicated molecules, but we still got some homework problems asking us to name them. Will we need to know the names of molecules and know their molecular formula for this class, or will they be provi...

Mario Reyes 1C

I like the car analogy that he used in class. You have to use the limiting reactant to find out how much product can be made, because that is the reactant that limits how much is produced. In other words, that is the maximum amount you can possibly get. In his analogy, he said that tires were the li...

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