CHEMISTRY COMMUNITY

rachel liu 3k

For the scope of this class, K A is just a measure of the relative strength of an acid. The higher the K A , the stronger the acid. The pK A is the -log K A . The lower the pK A , the stronger the acid. There is also K B and pK B (the same definitions but for a base instead. Usually, you will be gi...

rachel liu 3k

For the scope of this class, K A is just a measure of the relative strength of an acid. The higher the K A , the stronger the acid. The pK A is the -log K A . The lower the pK A , the stronger the acid. There is also K B and pK B (the same definitions but for a base instead. Usually, you will be gi...

rachel liu 3k

For the scope of this class, K A is just a measure of the relative strength of an acid. The higher the K A , the stronger the acid. The pK A is the -log K A . The lower the pK A , the stronger the acid. There is also K B and pK B (the same definitions but for a base instead. Usually, you will be gi...

rachel liu 3k

Annie Ye wrote:How do we know if a chemical formula is more polyprotic? How do we determine the strength?

more than 1 ionizable H+, such as H2PO4. The titration curve will have two equilibrium points because there are two points in which the OH- and H+ concentration equal one another.

rachel liu 3k

please quote this question so i get a notification. thanks in advance!
what are some molecules that are amphoteric but not amphiprotic? do we need to know molecules that fall into one category but not the other?

rachel liu 3k

please quote my question so i get a notification, thanks in advance! i know there is something wrong with my thought process, but i cannot figure it out. my thought process is that if a base is weaker, less oh- will be dissociated out. taking the -log of that smaller number will result in a smaller...

rachel liu 3k

KeyaV3A wrote:When a ligand has a prefix (di-, tri-, tetra-) you need to use bis- and tris. Ex. [Pt(H2NCH2CH2NH2)2Cl2]Cl2 -> dichlorobis(ethylenediamine)platinum(IV) chloride

Do you know if for diethylenetriamine, would (nh2ch2ch2nhch2ch2nh2)2 be bisdiethylenetriamine? it sounds kinda funky.

rachel liu 3k

For this problem, the choice showing dipole-dipole interactions between the molecules has the strongest attraction. In choice II, the partial positive H are nearest to the partial negative Cl, giving these molecules the strongest intermolecular interaction. In addition, you know that different mole...

rachel liu 3k

Yes that's correct. Dipole moments occur within a molecule when its polar bonds do not cancel out (it will have a net dipole moment). Dipole-dipole interactions are between two polar molecules that both have net dipole moments. Induced dipole-induced dipole interactions occur when two nonpolar mole...

rachel liu 3k

please quote my question in your answer so i get a notification. thanks in advance! why does SO2 have resonance structures? Isn't the best case scenario o double bond s double bond o? Although you are correct that it is the best case scenario, the other resonance structures are still valid, though ...

rachel liu 3k

please quote my question so i get a notification, thanks in advance! i know there is something wrong with my thought process, but i cannot figure it out. my thought process is that if a base is weaker, less oh- will be dissociated out. taking the -log of that smaller number will result in a smaller...

rachel liu 3k

please quote my question in your answer so i get a notification. thanks in advance!

why does SO2 have resonance structures? Isn't the best case scenario o double bond s double bond o?

rachel liu 3k

please reply to this by quoting my question so i get a notification. thanks in advance! what is the difference between dipole moments and induced dipoles and dipole-dipole interactions? From what I understand dipole moments are permanent dipoles within a molecule, between atoms (like C-F). Induced ...

rachel liu 3k

For this problem, the choice showing dipole-dipole interactions between the molecules has the strongest attraction. In choice II, the partial positive H are nearest to the partial negative Cl, giving these molecules the strongest intermolecular interaction. In addition, you know that different mole...

rachel liu 3k

Hydrogens are most often bonded to carbons when drawing lewis structures. Other than this, you can figure it out by looking at the formal charge. If the 2 hydrogens are bonded to the oxygen, the oxygen would have a formal charge of 2 and the carbons at the end of the structure would have formal cha...

rachel liu 3k

please reply to this by quoting my question so i get a notification. thanks in advance! what is the difference between dipole moments and induced dipoles and dipole-dipole interactions? From what I understand dipole moments are permenant dipoles within a molecule, between atoms (like C-F). Induced ...

rachel liu 3k

please reply to this by quoting my question so i get a notification. thanks in advance! how do you know to draw C2H5OC2H5 like the diagram below and not with 2 H attached to the Oxgen? Because that would dramatically increase the melting and boiling points due to the fact that now there are two pot...

rachel liu 3k

205150314 wrote:
rachel liu 3k wrote:
rachel liu 3k wrote:Does someone want to help me figure out what I did wrong? Thanks!

Nevermind, turns out I forgot how to do basic algebra and wasn't supposed to take out the 1/2. Thanks anyways!

this is the wrong answer though, isnt it?

Yes, it was.

rachel liu 3k

What is the difference or what distinguishes a coordinate covalent bond from a regular bond? In a coordinate covalent bond both electrons come from the same atom while in a regular bond each atom provides an electron. Oh, got it! The only way you would know the type of bond (coordinate covalent vs ...

rachel liu 3k

605110118 wrote:Do we need to know how to draw the shape of different bonds?

Drawing out the 3-d molecule-based from the bonding seen in the Lewis structure helps greatly to determine the shape, so it is recommended to draw the shape of the bonds before naming it.

rachel liu 3k

Are we going to be touching on sigma and pi bonds later on (perhaps when we start the Shapes section)? Because it seems that so far we have stuck to the topics on this website pretty closely, but we've skipped this topic save for a brief mention once in lecture. Thank you! They will be covered next...

rachel liu 3k

405404782 Gabriel Rigole 4F wrote:Can someone explain hybridization and how to determine what the hybridization of a molecule is?

Just like what Eileen said, the hybridization of the molecule depends on the number of bonds around the atom in question. Dr. Lavelle will talk about it more after Test #2.

rachel liu 3k

First, I just set up the molecule as described in the problem. From there, I added all of the 22 other electrons onto the atoms to give them octets. At first I gave Cl 6 free electrons, Oxygen 4, Nitrogen 0 and each of the oxygens 6. However, with this setup, nitrogen didn't have an octet. So, I mo...

rachel liu 3k

Polarizability is referring to how easily displaced an atom's electrons are by neighboring atoms. In an ionic bond, ions which cause large distortions are referred to as having 'high polarizing power'. This distorts the electron density of an ion, so the electrons are being pulled into the bonding ...

rachel liu 3k

Polarizability is referring to how easily displaced an atom's electrons are by neighboring atoms. In an ionic bond, ions which cause large distortions are referred to as having 'high polarizing power'. This distorts the electron density of an ion, so the electrons are being pulled into the bonding ...

rachel liu 3k

8. B) A newly designed laser pointer with a certain frequency is pointed at a sodium at a sodium metal surface. An electron is ejected from the metal surface with wavelength 1.10nm. What is the frequency of the light from the laser pointer? The work function of sodium is 150.6 kJmol^1. I understand...

rachel liu 3k

8. B) A newly designed laser pointer with a certain frequency is pointed at a sodium at a sodium metal surface. An electron is ejected from the metal surface with wavelength 1.10nm. What is the frequency of the light from the laser pointer? The work function of sodium is 150.6 kJmol^1. I understand...

rachel liu 3k

Radha Patel 1A wrote:Polarizability -
- Generally for anions, are electrons that are further away from the nucleus
- more energy shells = more polarizability
Polarizing power- Generally for cations, are less electrons closer to the nucleus
- less electron shells = more polarizing power

Super helpful, thanks!!

rachel liu 3k

Will there every be a time when the formal charge is not 0 but it is the most stable structure for the atom? I agree with Zaynab, but know that there must be a mistake in your calculation of the individual formal charges of the atoms within the molecule (even if it is not the most stable), does not...

rachel liu 3k

I noticed that Nitrogen has a quite high electronegativity value of 3.04 but has a very low electron affinity of almost 0. I understand that Nitrogen has such a low electron affinity because adding an electron to its stable half-full 2p subshell is actually energetically unfavorable. But why does N...

rachel liu 3k

I noticed that Nitrogen has a quite high electronegativity value of 3.04 but has a very low electron affinity of almost 0. I understand that Nitrogen has such a low electron affinity because adding an electron to its stable half-full 2p subshell is actually energetically unfavorable. But why does N...

rachel liu 3k

how can we tell which molecules will have a greater dipole-dipole or London force? aka what factors contribute to the strength of dipole-dipole interactions? Addressing the second part of your question, dipole-dipole interactions increase as the polarity of atoms/molecules increase. Polarity is due...

rachel liu 3k

First, I just set up the molecule as described in the problem. From there, I added all of the 22 other electrons onto the atoms to give them octets. At first I gave Cl 6 free electrons, Oxygen 4, Nitrogen 0 and each of the oxygens 6. However, with this setup, nitrogen didn't have an octet. So, I mo...

rachel liu 3k

A single bond is a sigma bond, whereas a double bond is a sigma bond and a pi bond. A sigma bond is a basic covalent bond, with the bond in line with the bonding orbitals. Only one sigma bond can exist between any two atoms. A pi bond is a covalent bond between orbitals that are perpendicular to bo...

rachel liu 3k

I have a few questions regarding dissociation energy and bond length relationships 1. Do all bond types have the same dissociation energy (all C-H bonds = 412 kJ/mol?) 2. Since double bonds have an increased dissociation energy than single bonds, can we assume shorter bonds have larger dissociation...

rachel liu 3k

the answer key says c-o, but the explanation doesn't sound right. It says that since o is the smallest, but both n and c are smaller, so I really don't know. It C=O because the two ions have the greatest difference in electronegativity. Oxygen has a greater nuclear pull and will pull the shared ele...

rachel liu 3k

Kelvin Chung 1C wrote:
Jordan Young 3E wrote:Boron also is an exception at times

Boron typically has 6 valence electrons, forming 3 covalent bonds. Right?

Yup!

rachel liu 3k

On the basis of the expected charges on the monatomic ions, give the chemical formula of each of the following compounds: (a) magnesium arsenide; (b) indium(III) sulfide; (c) aluminum hydride; (d) hydrogen telluride; (e) bismuth(III) fluoride Can someone explain the roles of the roman numerals? The...

rachel liu 3k

When we put dots to represent valence electrons for elements, is there any rule on where (start putting dots on the left side, right side, etc.) to start drawing the dots? Like everyone else has said, there is no rule, but make sure to follow Hund's Rule. Put one valence electron in per orital firs...

rachel liu 3k

i thought it dosn't have to be bonded to the same element...as long as there is variance in the bond lengths according to the lewis diagram. am i misunderstanding?

rachel liu 3k

Are we expected to draw all the resonance structures of compounds various bond lengths (no3-) when asked for a lewis structure?

rachel liu 3k

Is the fastest thing in the world really light? like for sure for sure?

rachel liu 3k

In high school, I had to memorize all three of these rules (Pauli, Hund's and Aufbau), so I made weird mnemonics to help with it. Pauli Exclusion Principle: well this one you could remember that at PAULI Pavillion, every person has a different and unique seat, just like how no electron has the same ...

rachel liu 3k

I'm a little confused on the difference between the Aufbau Principle and Hund's Rule...don't they both pretty much mean you fill the lower energy levels first and then build your way up?

rachel liu 3k

Why is it that when we are dealing with energy levels, as the energy levels increase, they get closer together? Does this also affect our calculations with the Bohr frequency condition or the E=-hR/n^2 formula in any way? As of now, the Rydberg formula (E=-hR/n^2), and the concepts of Balmer and Ly...

rachel liu 3k

melinak1 wrote:we can still use a scientific calculator for the exam, right?

Yes, as long as it is non-graphing!

rachel liu 3k

Are black bodies related to black holes?

rachel liu 3k

In class, Professor Lavelle wrote the Rydberg equation with a negative sign on the right to show that energy was being lost. Unfortunately when I used the equation that way, my negatives got all messed up and my answer was wrong...Should I just forget that negative?

rachel liu 3k

Does anyone know if points will be taken off due to sig figs? My high school chem teacher was super specific on SFs.

rachel liu 3k

Is there somewhere on the website where the Equation Sheet given on the test is posted? I want to know exactly what conversions we are given so I know what to memorize...

rachel liu 3k

Are the variables "E" is E=hc/wavelength, and the E_k in the threshold energy equation the same?

rachel liu 3k

Hi Sophia! In my opinion, it is much better to keep as many S.F. as possible and then round at the end. In other classes that ask you to submit answers online, the websites (Pearson) get really nit-picky about getting exactly the right number and will mark answers wrong if you are even off by .01. H...

rachel liu 3k

Dear Dr. Lavelle,
I know the class has barely started but I just want to take a moment to appreciate the little dance you do to your presentation music before class begins. It is wholesome and precious and makes my day. Thank you.

rachel liu 3k

Dr. Lavelle said in class today...if hydrogen, carbon, and oxygen are present in the reactants, it is most likely a combustion reaction!

rachel liu 3k

Must the states of matter always be written in a chemical equation? (s,l,aq)

rachel liu 3k

This was such a great share.. emphasizing the importance of enjoying the present, whatever that may be. I know it's very early, but for the past few weeks, I have been struggling to decide whether I should go to med school, or even stay within a STEM-related major. I feel if I don't decide soon, it ...

Search found 56 matches