Search found 45 matches
- Fri Jun 08, 2018 6:33 pm
- Forum: Dipole Moments
- Topic: Why can't SO2 form Hydrogen bonds?
- Replies: 3
- Views: 2560
Why can't SO2 form Hydrogen bonds?
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?
- Fri Jun 08, 2018 6:15 pm
- Forum: Dipole Moments
- Topic: Are London dispersion forces present in every molecule?
- Replies: 2
- Views: 482
Are London dispersion forces present in every molecule?
Is it safe to say that London dispersion forces are present in every molecule? Are these forces within the molecule, or between neighboring molecules?
- Mon Jun 04, 2018 9:11 pm
- Forum: Hybridization
- Topic: sp^3d or dsp^3
- Replies: 6
- Views: 825
sp^3d or dsp^3
Does it matter which way you write a hybridization with 5 regions of electron density? Is either way of writing it correct?
- Sat Jun 02, 2018 9:48 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Significance of Coordination Number?
- Replies: 7
- Views: 2588
Significance of Coordination Number?
Professor Lavelle stressed that the number of bonds equals the coordination number, but what makes the coordination number significant?
- Sat Jun 02, 2018 9:37 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Chelate? [ENDORSED]
- Replies: 2
- Views: 409
Chelate? [ENDORSED]
I am a little confused on what a chelate is. Can someone explain?
- Mon May 28, 2018 2:07 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: I3- Molecular Shape
- Replies: 2
- Views: 1675
I3- Molecular Shape
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?
- Sun May 27, 2018 6:22 pm
- Forum: Sigma & Pi Bonds
- Topic: Logic behind Sigma and Pi bonds?
- Replies: 2
- Views: 522
Logic behind Sigma and Pi bonds?
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?
- Fri May 25, 2018 12:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Why do lone pairs occupy the most space? [ENDORSED]
- Replies: 3
- Views: 4369
Why do lone pairs occupy the most space? [ENDORSED]
Lone pairs have the greatest repulsion strength because they occupy the most volume, but how do they occupy more volume than a bonding pair?
- Mon May 21, 2018 5:56 pm
- Forum: Lewis Structures
- Topic: Lewis Structure tips?
- Replies: 2
- Views: 449
Lewis Structure tips?
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...
- Sun May 20, 2018 9:42 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Why don't we find the formal charge of Hydrogen?
- Replies: 3
- Views: 535
Re: Why don't we find the formal charge of Hydrogen?
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?
- Sun May 20, 2018 9:31 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Why don't we find the formal charge of Hydrogen?
- Replies: 3
- Views: 535
Why don't we find the formal charge of Hydrogen?
This may have a simple answer, but why don't we find the formal charge of hydrogen in molecules?
- Sun May 20, 2018 5:51 pm
- Forum: Ionic & Covalent Bonds
- Topic: 3.25 c)
- Replies: 4
- Views: 656
Re: 3.25 c)
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...
- Sun May 20, 2018 4:43 pm
- Forum: Lewis Structures
- Topic: 3.33 c). Ionization energy question.
- Replies: 4
- Views: 489
Re: 3.33 c). Ionization energy question.
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...
- Sun May 20, 2018 4:38 pm
- Forum: Lewis Structures
- Topic: 3.33 c). Ionization energy question.
- Replies: 4
- Views: 489
Re: 3.33 c). Ionization energy question.
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...
- Sun May 20, 2018 4:06 pm
- Forum: Lewis Structures
- Topic: 3.33 and ionization energy
- Replies: 3
- Views: 466
Re: 3.33 and ionization energy
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?
- Sun May 20, 2018 4:02 pm
- Forum: Lewis Structures
- Topic: 3.33 c). Ionization energy question.
- Replies: 4
- Views: 489
3.33 c). Ionization energy question.
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.
- Sun May 20, 2018 2:55 pm
- Forum: Ionic & Covalent Bonds
- Topic: 3.25 c)
- Replies: 4
- Views: 656
3.25 c)
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.
Al has a 3+ charge, and I think Hydride is referring to Hydrogen. I am confused on what charge Hydrogen would have.
- Sun May 20, 2018 2:07 pm
- Forum: Dipole Moments
- Topic: Difference between Dipole-Dipole and Dipole-Induced dipole?
- Replies: 2
- Views: 435
Difference between Dipole-Dipole and Dipole-Induced dipole?
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?
- Sun May 20, 2018 2:03 pm
- Forum: Dipole Moments
- Topic: London Dispersion, Induced dipole- Induced dipole, Van Der Waals
- Replies: 5
- Views: 622
London Dispersion, Induced dipole- Induced dipole, Van Der Waals
In class Professor Lavelle said these are all similar, so is there really no difference to these forces besides the name?
- Fri May 18, 2018 3:43 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Does being more polarizable= Being stronger?
- Replies: 5
- Views: 3245
Does being more polarizable= Being stronger?
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...
- Sun May 13, 2018 1:36 pm
- Forum: Resonance Structures
- Topic: Resonance Structures
- Replies: 5
- Views: 2731
Re: Resonance Structures
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.
- Sun May 13, 2018 1:31 pm
- Forum: Lewis Structures
- Topic: Lewis Structures
- Replies: 4
- Views: 591
Re: Lewis Structures
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.
- Sun May 13, 2018 1:26 pm
- Forum: Lewis Structures
- Topic: Ammonium Sulfate Example in Notes
- Replies: 2
- Views: 364
Re: Ammonium Sulfate Example in Notes
Be sure to skip the transition metals when trying to count the number of valence electrons from left to right.
- Tue May 08, 2018 1:13 pm
- Forum: Trends in The Periodic Table
- Topic: Does Sulfur or Phosphorus have a larger ionization energy?
- Replies: 3
- Views: 13927
Does Sulfur or Phosphorus have a larger ionization energy?
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?
- Mon May 07, 2018 3:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing Lewis Structures
- Replies: 5
- Views: 722
Drawing Lewis Structures
When drawing a lewis structure, why do we choose the atom with the lowest ionization energy as the central atom?
- Sun May 06, 2018 11:26 pm
- Forum: Trends in The Periodic Table
- Topic: 2.67 part c) and d) [ENDORSED]
- Replies: 5
- Views: 698
Re: 2.67 part c) and d) [ENDORSED]
I'm confused by the reasoning. I thought electron affinity was dealing with adding electrons, not taking them away.
- Sun May 06, 2018 9:23 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Why isn't Vanadium an exception?
- Replies: 2
- Views: 1827
Why isn't Vanadium an exception?
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?
- Sun May 06, 2018 9:07 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: f block elements
- Replies: 2
- Views: 445
f block elements
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?
- Wed May 02, 2018 1:29 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: What does ground state mean? [ENDORSED]
- Replies: 4
- Views: 935
What does ground state mean? [ENDORSED]
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?
- Wed May 02, 2018 12:43 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Principle quantum number and orbital angular momentum quantum number
- Replies: 2
- Views: 399
Re: Principle quantum number and orbital angular momentum quantum number
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.
- Sun Apr 29, 2018 1:19 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Short hand? [ENDORSED]
- Replies: 1
- Views: 355
Short hand? [ENDORSED]
When using short hand, when can you only use preceding inner gases? Why can't you use any other element before it?
- Sun Apr 29, 2018 1:17 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: What does electron spin actually mean? [ENDORSED]
- Replies: 9
- Views: 3422
What does electron spin actually mean? [ENDORSED]
When saying two electrons spin in opposite directions, what is that really saying?
- Fri Apr 27, 2018 3:33 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Why does the 4s orbital come before the 3d?
- Replies: 7
- Views: 1907
Why does the 4s orbital come before the 3d?
If I heard correctly in class, the 4s orbital comes before 3d only for elements with 20 electrons or less. Can somebody explain why?
- Sun Apr 22, 2018 10:58 pm
- Forum: DeBroglie Equation
- Topic: Post-Assessment #34 [ENDORSED]
- Replies: 5
- Views: 519
Re: Post-Assessment #34 [ENDORSED]
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
- Sun Apr 22, 2018 10:47 pm
- Forum: DeBroglie Equation
- Topic: How do you calculate speed using the De Broglie equation? [ENDORSED]
- Replies: 6
- Views: 4182
Re: How do you calculate speed using the De Broglie equation? [ENDORSED]
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.
- Sun Apr 22, 2018 10:24 pm
- Forum: DeBroglie Equation
- Topic: How do you calculate speed using the De Broglie equation? [ENDORSED]
- Replies: 6
- Views: 4182
How do you calculate speed using the De Broglie equation? [ENDORSED]
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?
- Mon Apr 16, 2018 8:46 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: #42 In Post-Module Assessment [ENDORSED]
- Replies: 5
- Views: 419
Re: #42 In Post-Module Assessment [ENDORSED]
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
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
- Mon Apr 16, 2018 6:43 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: #42 In Post-Module Assessment [ENDORSED]
- Replies: 5
- Views: 419
#42 In Post-Module Assessment [ENDORSED]
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...
- Sun Apr 15, 2018 4:20 pm
- Forum: Photoelectric Effect
- Topic: Intensity VS Energy Models? [ENDORSED]
- Replies: 4
- Views: 563
Re: Intensity VS Energy Models? [ENDORSED]
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...
- Sun Apr 15, 2018 12:36 pm
- Forum: Properties of Light
- Topic: Threshold Energy [ENDORSED]
- Replies: 3
- Views: 269
Re: Threshold Energy [ENDORSED]
If you are given the energy of the photon and the excess energy, you can solve for the threshold energy by adding them together.
- Sun Apr 15, 2018 12:32 pm
- Forum: Photoelectric Effect
- Topic: Intensity VS Energy Models? [ENDORSED]
- Replies: 4
- Views: 563
Re: Intensity VS Energy Models? [ENDORSED]
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...
- Thu Apr 12, 2018 5:09 pm
- Forum: Photoelectric Effect
- Topic: Why do shorter wavelengths have more energy than longer wavelengths?
- Replies: 4
- Views: 6821
Why do shorter wavelengths have more energy than longer wavelengths?
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.
- Sun Apr 08, 2018 10:59 pm
- Forum: SI Units, Unit Conversions
- Topic: Moles mols mol? [ENDORSED]
- Replies: 21
- Views: 9303
Re: Moles mols mol? [ENDORSED]
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.
- Sun Apr 08, 2018 10:56 pm
- Forum: Balancing Chemical Reactions
- Topic: Naming Molecules [ENDORSED]
- Replies: 1
- Views: 250
Naming Molecules [ENDORSED]
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...
- Sun Apr 08, 2018 10:51 pm
- Forum: Limiting Reactant Calculations
- Topic: Limiting Reagent and finding amount produced
- Replies: 2
- Views: 506
Re: Limiting Reagent and finding amount produced
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...