## Search found 117 matches

Sun Oct 28, 2018 6:05 pm
Forum: Ionic & Covalent Bonds
Topic: Topic 2A.1 (valence electrons) 7th edition
Replies: 3
Views: 129

### Re: Topic 2A.1 (valence electrons) 7th edition

There can only be 8 valence electrons tops so 15 would be invalid, but Sb has 5 because going from left to right in its period it's 5th, meaning it has 5 valence electrons (you skip d-block when counting the valence electrons). There is probably a more in depth, scientific way of calculating it usin...
Sun Oct 28, 2018 3:48 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: when 4s goes after 3d??
Replies: 2
Views: 92

### when 4s goes after 3d??

Hello, I'm still a little confused as to when you put 4s after 3d orbitals and why in the electron configuration, if you could explain it in simplest terms possible that would be great, thank you!
Tue Oct 23, 2018 6:05 pm
Forum: Properties of Light
Topic: Electron energy levels??
Replies: 1
Views: 111

### Electron energy levels??

This question was on the atomic spectra post module assessment: An excited hydrogen atom emits light with a frequency of 1.14 x 1014 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin? The way I tried solving it is using v=(delta)E/h where I first do v*h=(delt...
Tue Oct 23, 2018 4:14 pm
Forum: Properties of Light
Topic: Atomic Spectra
Replies: 2
Views: 97

### Atomic Spectra

For test 2, should we know about atomic spectra? It was one of the video modules for us to watch but I don't really remember us going over it that much in class, thanks!
Sun Oct 21, 2018 12:09 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron configurations
Replies: 2
Views: 69

### Electron configurations

So I understand that for the electron configurations you put the noble gas and then continue but are you just supposed to already know the electron configuration of each noble gas?? How do you know that the noble gas Kr went up to 4p^6 without looking/memorization? I feel like there has to be some w...
Thu Oct 18, 2018 7:09 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Video Modules
Replies: 7
Views: 171

### Re: Video Modules

There are no more video modules past that one, it was just for those topics. At least as of now, of course who knows maybe new ones will be created but you're good for now!
Mon Oct 15, 2018 10:41 pm
Forum: Einstein Equation
Topic: Question regarding wavelength
Replies: 5
Views: 107

### Re: Question regarding wavelength

the first equation requires you to know the frequency (v) so depending if you have that or not given to you, you would use that equation. It is also used for most calculations; the second equation you mention is more specific to find the wavelength of a photon with a certain energy. In the end both ...
Mon Oct 15, 2018 9:16 pm
Forum: *Particle in a Box
Topic: Hw assignment?
Replies: 7
Views: 450

### Hw assignment?

For week 3, are we still on the Quantum World part of the syllabus? I thought it was one topic for each week but theres only 6 topics and 10 weeks so do you just go by what we talked about in class? Does that mean we can still do quantum world hw problems for this week (3) or should we move onto che...
Tue Oct 09, 2018 6:10 pm
Forum: Photoelectric Effect
Replies: 2
Views: 78

### Re: Frequency vs. Wavelength adn energy of electronmagnetic radiation HW question

C would be correct because EM radiation is kind of like light since its a type of EM wave; the energy per photon of light equation tells us that the energy per photon is proportional to frequency so if frequency decreases then energy does as well within the field, and extent of change can be interpr...
Tue Oct 09, 2018 6:00 pm
Forum: Photoelectric Effect
Topic: Vacuum
Replies: 4
Views: 129

### Re: Vacuum

Molecules of air are made of atoms which have their own electrons therefore if not in a vacuum electrons in the experiment could interact with the air molecule electrons and the data would be changed, also considering things in a vacuum makes calculations much easier because you can disregard air re...
Tue Oct 09, 2018 5:55 pm
Forum: SI Units, Unit Conversions
Topic: Scientific Notation
Replies: 7
Views: 214

### Re: Scientific Notation

Scientific notation is most likely used in that sense if they are paying attention to significant figures in the calculations. Depending on the least amount of sig figs in one of ur numbers for calculation, you might put your answer into scientific notation to match the number of sig figs.
Thu Oct 04, 2018 1:40 pm
Forum: SI Units, Unit Conversions
Topic: Grams to atom Conversions [ENDORSED]
Replies: 1
Views: 68

### Re: Grams to atom Conversions[ENDORSED]

a formula unit is technically a molecule with an ionic bond, but the TA said we dont really have to know that right now. When computing the number of moles of atoms/molecules/formula units you kind of just consider them all the same. I just use the formula: # of objects= # of moles * Avo's Number , ...
Thu Oct 04, 2018 1:35 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Ed. 7 E.23D Equation
Replies: 3
Views: 73

### Re: Ed. 7 E.23D Equation

The dot is used in formulas where water molecules can only be bound with intermolecular interactions like hydrogen bonds, but they still exist in the structure in a stoichiometric ratio, hence the stoichiometric coefficient before the H20
Thu Oct 04, 2018 1:25 pm
Forum: Limiting Reactant Calculations
Topic: chemical formula regarding M.9
Replies: 2
Views: 93

### Re: chemical formula regarding M.9

The roman numerals stand for the charge on the atom, so copper (ll) Nitrate means that the copper has to have a +2 charge so the net charge would be zero on the molecule. Cu(NO3)2 would be written out Copper (ll) Nitrate. The rule is that for cations that can have multiple charges, you use roman num...
Fri Sep 28, 2018 8:33 pm
Forum: SI Units, Unit Conversions
Topic: Standard SI Unit, Question E1
Replies: 3
Views: 170

### Re: Standard SI Unit, Question E1

You are correct, meters are the SI unit for length. The TA chose to convert to km right away instead of meters when going from pm to km, you should ask him next week because I am still not completely sure why as well.
Fri Sep 28, 2018 8:24 pm
Forum: SI Units, Unit Conversions
Topic: How does grading for discussion posts work?
Replies: 80
Views: 2690

### Re: How does grading for discussion posts work?

I also had a question on this, by what day/time is the cut off for each week??
Fri Sep 28, 2018 8:19 pm
Forum: Empirical & Molecular Formulas
Topic: Percent Composition
Replies: 5
Views: 224

### Re: Percent Composition

Yes, I think so because the subscript gives either the exact number of that atom (molecular formula) or a ratio (empirical). So depending on which formula it is, oxygen would be the most either way. I'd say you could simply do 3/5 (total atoms) and get about 60 %