## Search found 12 matches

Sun Nov 27, 2016 11:58 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Change in molarity
Replies: 2
Views: 388

### Change in molarity

Why is it that for one example on the course reader we had to calculate the change in concentration but for two other examples we assigned the change an concentration an unknown value, "x"?
Do we always say it's "x" or do we calculate in certain instances and if so, what instances?
Wed Nov 16, 2016 11:40 pm
Forum: Hybridization
Topic: Polar/nonpolar [ENDORSED]
Replies: 14
Views: 1629

### Polar/nonpolar[ENDORSED]

can someone review the difference between polar and nonpolar molecules?
Mon Nov 07, 2016 12:43 am
Forum: Ionic & Covalent Bonds
Topic: ionic vs. covalent bonds
Replies: 2
Views: 450

### ionic vs. covalent bonds

what is meant when is said "heteronuclear atoms with an electronegativity difference >2 considered mainly ionic bonds" and "<1.5 considered mainly covalent bonds"?
Mon Oct 31, 2016 8:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar/nonpolar molecules
Replies: 3
Views: 490

### Polar/nonpolar molecules

What is a difference between polar and nonpolar? What does it mean for dipole moments to "cancel" depending on whether they are polar or nonpolar?
Thu Oct 27, 2016 10:08 pm
Forum: Sigma & Pi Bonds
Topic: sigma/pi bonds [ENDORSED]
Replies: 1
Views: 353

### sigma/pi bonds[ENDORSED]

on the quiz 2 prep, how is the answer 12 sigma and 1 pi?
can someone explain how to arrive at that answer because i'm not understanding the concept, is it mathematical and if so, how?
Wed Oct 26, 2016 1:14 am
Forum: Ionic & Covalent Bonds
Topic: Double Bonds
Replies: 1
Views: 272

### Double Bonds

What are the restrictions on creating double bonds?
I know some lone electrons can't turn into double bonds because the formal charge will change but how would we know that? We have to actually calculate every time?
Tue Oct 18, 2016 7:21 pm
Forum: Resonance Structures
Topic: Formal Charge [ENDORSED]
Replies: 3
Views: 547

### Formal Charge[ENDORSED]

1) I don't get how turning the electron dots into dashes (one dash represents an electron pair) makes a bond "more stable". 2) Also what does "formal charge" mean? For example, one sulfur atom in the middle (it's in the middle because ionization energy is lower than oxygen's ioni...
Fri Oct 14, 2016 10:29 am
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 5
Views: 750

### Re: Photoelectric Effect

But how does multiplying nm times nm cancel out nm to become meters??? wouldn't it have to be divided (m/nm) ?
Thu Oct 13, 2016 11:47 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 5
Views: 750

### Photoelectric Effect

When plugging into E=hc/lambda, and a incoming wavelength is given, do you take that wavelength and plug it into the denominator? Because in an example from my discussion section the given wavelength was plugged in but was also multiplied by (10^-9) and I have no idea why... I know 1 m is 10^9 nm, d...
Fri Oct 07, 2016 12:29 am
Forum: Photoelectric Effect
Topic: photoelectric effect post assessment #17: work function
Replies: 2
Views: 457

### Re: photoelectric effect post assessment #17: work function

During my discussion section (4L), the class was solving for velocity of E given threshold energy and wavelength of E. For some reason we multiplied the given threshold energy by 1 electron voltage (1.602x10^-19). Why would we need to do that?? Follow up question: what are the units of electron volt...
Fri Sep 30, 2016 7:29 pm
Forum: Properties of Light
Topic: Wavelength, Frequency, Amplitude, & Intensity
Replies: 4
Views: 3846

### Re: Wavelength, Frequency, Amplitude, & Intensity

Energy of a photon is directly proportional to frequency

When you increase intensity of light, you increase number of photons. However increasing intensity of light doesn't mean electrons will be emitted.
Fri Sep 30, 2016 7:22 pm
Forum: Significant Figures
Topic: Basic Sig Figs
Replies: 13
Views: 1228

### Re: Basic Sig Figs

I don't understand why trailing zeros are not counted as sig figs.. can someone explain?