## Search found 31 matches

Mon Jun 11, 2018 6:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T-Shape
Replies: 6
Views: 336

### Re: T-Shape

You need to consider that a T shape has different bond angles within it, they are not all identical.
Mon Jun 11, 2018 6:54 pm
Forum: DeBroglie Equation
Topic: DeBroglie
Replies: 5
Views: 419

### Re: DeBroglie

given the mass and the velocity you can use the DeBroglie equation to figure out the object in motion's wavelength. This is useful when you are attempting to figure out the wavelength of a particle or a body of mass.
Mon Jun 11, 2018 6:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal bipyramidal and octahedral family [ENDORSED]
Replies: 2
Views: 248

### Re: Trigonal bipyramidal and octahedral family[ENDORSED]

I think that we should know how to do all the VSEPR shapes that were showcased and worked through in class, and in the homework problems. Good luck (:
Mon Jun 11, 2018 6:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Atom vs lone pair
Replies: 3
Views: 194

### Re: Atom vs lone pair

lone pairs each have a negative charge, and they also have to respond to the charges of the atoms, making them push in the directions that they do push in. Think of it as a bunch of magnets of identical charges.
Tue May 29, 2018 10:50 am
Forum: Ionic & Covalent Bonds
Topic: Double/Triple Bonds
Replies: 8
Views: 476

### Re: Double/Triple Bonds

All atoms have the capacity but it depends on the whole molecule. You want to make it as stable as possible.
Tue May 29, 2018 10:47 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angle
Replies: 9
Views: 416

### Re: Bond angle

Think of the electron charge, because electron pairs are negatively charged they repel other negatively charged particles, like other electron pairs. They also repel molecules but not with the same force that they do lone pairs.
Tue May 29, 2018 10:43 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Cancelling out dipole moments
Replies: 3
Views: 406

### Re: Cancelling out dipole moments

I would draw the direction of the arrows, if you look like they are positioned in obvious opposite directions, they cancel out. If it is not obvious I would draw vector diagrams like in high school physics, determine the x and y components and figure out whether or not the directions cancel the magn...
Sun May 20, 2018 5:34 pm
Forum: Ionic & Covalent Bonds
Topic: Octet rule
Replies: 17
Views: 890

### Re: Octet rule

How do you know when atoms can break the octet rule? or which atoms can break the octet rule? These are just exceptions that need to be memorized, but I don't think we need to worry too much about them. just be familiar in general with the idea that there are atoms that do not agree with the octet ...
Sun May 20, 2018 5:31 pm
Forum: Ionic & Covalent Bonds
Topic: Which is more Ionic
Replies: 2
Views: 155

### Re: Which is more Ionic

I googled your question and came across someone who had the same question as you back in 2011:
viewtopic.php?t=4306
I hope the replies help :)
Sun May 20, 2018 5:26 pm
Forum: Ionic & Covalent Bonds
Topic: 3.25 c)
Replies: 4
Views: 279

### 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 :)
Mon May 14, 2018 11:19 am
Forum: Photoelectric Effect
Topic: Incoming Light [ENDORSED]
Replies: 4
Views: 387

### Re: Incoming Light[ENDORSED]

It is definitely UV light as proven by the Ultraviolet catastrophe.
Mon May 14, 2018 11:15 am
Forum: Ionic & Covalent Bonds
Topic: VALENCE ELECTRONS [ENDORSED]
Replies: 16
Views: 917

### Re: VALENCE ELECTRONS[ENDORSED]

I like to use the group numbers and subtract 10 as we approach the non-metals.
Mon May 14, 2018 11:14 am
Forum: Lewis Structures
Topic: Dots or lines [ENDORSED]
Replies: 5
Views: 297

### Re: Dots or lines[ENDORSED]

I believe that it's fine to use lines since Dr. Lavelle uses dots simply to erase confusion before delving into the concept. I think moving forward we will be using the system of lines in class.
Mon May 14, 2018 11:11 am
Forum: Electronegativity
Topic: Trends? [ENDORSED]
Replies: 10
Views: 842

### Re: Trends?[ENDORSED]

We went over atomic radius, ionic radius, ionic energy and electron affinity in class.
Mon May 14, 2018 11:09 am
Forum: General Science Questions
Topic: Conceptual Questions
Replies: 4
Views: 356

### Re: Conceptual Questions

I find it really helpful to watch videos on the concept, I like Crash Course Chemistry. I watch the video and take notes on it. It's also helpful to explain the concept to other people. If you can explain the concept without using notes you have a full understanding of the concept.
Sun May 13, 2018 8:19 pm
Forum: Lewis Structures
Topic: Valence shell on Noble gases
Replies: 4
Views: 274

### Re: Valence shell on Noble gases

No, Noble gasses have a full valence shell and do not need any electrons to become stable.
Sun May 13, 2018 8:18 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent vs Metallic Bonds
Replies: 6
Views: 468

### Re: Ionic vs Covalent vs Metallic Bonds

An ionic bond is the transfer of electrons from an non-metal to a metal, a covalent bond is when two non-metals share electrons and metallic bond is when a metal exists within a mass of electrons.
Sun May 13, 2018 8:11 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Equation
Replies: 3
Views: 230

### Re: Equation

I would use the one we learnt in class to get my answer and use the high school one to check my answer.
Sun May 13, 2018 8:05 pm
Forum: Administrative Questions and Class Announcements
Topic: Returned midterms
Replies: 1
Views: 195

### Re: Returned midterms

I believe they will be handed back in discussions either way but if you can't make it, go to either your TA's office hours or Dr. Lavelle's :)
Wed Apr 25, 2018 8:38 am
Forum: Properties of Light
Topic: test 2
Replies: 18
Views: 859

### Re: test 2

I would put extra effort into having a full understanding of the concepts. Once you've got calculations down and have done the practice, focus more on the concept behind that calculation. There is no point in practicing redundantly if you don't understand what your calculations mean or what the foun...
Wed Apr 25, 2018 8:33 am
Forum: Photoelectric Effect
Topic: Difference between photon and particle?
Replies: 2
Views: 186

### Re: Difference between photon and particle?

A photon is a packet of energy or light whereas a particle is a subatomic unit such as electron, neutrons and protons. Also, traditionally photons do not have masses whereas particles do.
Wed Apr 25, 2018 8:29 am
Forum: Photoelectric Effect
Topic: Frequency on Photoelectric Effect
Replies: 5
Views: 298

### Re: Frequency on Photoelectric Effect

Since it's a one photon to one atom to one electron interaction increasing the number of photons (increasing the intensity) should increase the number of electrons ejected, this answers your second question. However, you need to keep in mind that different metals have different work functions and th...
Sun Apr 22, 2018 11:40 am
Forum: Properties of Light
Topic: still don't uderrsatnd what a photon is [ENDORSED]
Replies: 20
Views: 594

### Re: still don't uderrsatnd what a photon is[ENDORSED]

I like to think of a photon as a packet of light/energy.
Sun Apr 22, 2018 11:38 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 1J=1kg.m^2.s^-2
Replies: 3
Views: 140

### Re: 1J=1kg.m^2.s^-2

If you think about the equation for kinetic energy you see that Ek=(1/2)mv^2. (1/2) is a constant and has no units. Mass has units in Kg and velocity is measured in m/s. The equation asks you to square velocity and if you think about your exponent laws (m/s)^2 comes out to be m^2/s^2. This equation ...
Sun Apr 22, 2018 11:25 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Calculating energy [ENDORSED]
Replies: 3
Views: 215

### Re: Calculating energy[ENDORSED]

I suggest using unit cancellation or dimensional analysis to solve questions like these. You have all the equations you need and the givens required to use simple cancellation and number crunching :)
Thu Apr 12, 2018 9:50 am
Forum: Limiting Reactant Calculations
Topic: Knowing if it's Limiting Reactions
Replies: 6
Views: 362

### Re: Knowing if it's Limiting Reactions

I would just be prepared in general with a founded understanding. Also I suggest that you do all the limiting reactant questions that were "assigned" for homework :)
Thu Apr 12, 2018 9:47 am
Forum: Properties of Light
Topic: HW 1.7 (speed of light) clarification
Replies: 4
Views: 170

### Re: HW 1.7 (speed of light) clarification

I believe that the speed of light with the exact number of sig-digs preferred by Dr Lavelle is on the formula sheet given to us in tests :)
Thu Apr 12, 2018 9:45 am
Forum: Properties of Light
Topic: HW 1.5 [ENDORSED]
Replies: 7
Views: 442

### Re: HW 1.5[ENDORSED]

To calculate anything about frequency or energy you would need to be given wavelength. This question is testing general knowledge of electromagnetic radiation. The question assumes that you know the order.
Sun Apr 08, 2018 5:38 pm
Forum: Administrative Questions and Class Announcements
Topic: Lecture Outlines [ENDORSED]
Replies: 2
Views: 151

### Re: Lecture Outlines[ENDORSED]

I am sure that Dr. Lavelle will make it clear when he switched from one to the other :)
Sun Apr 08, 2018 5:36 pm
Forum: Limiting Reactant Calculations
Topic: Actual Yield [ENDORSED]
Replies: 3
Views: 230

### Re: Actual Yield[ENDORSED]

Because actual yield depends on side reactions, human error, and other experimental mishaps, it is hard with our level of understanding of chemistry to measure actual yield. As of now we have been calculating chemical problems within a very theoretical and almost perfect sphere, where reactions are ...
Sun Apr 08, 2018 5:30 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding atomic weight (general question) [ENDORSED]
Replies: 8
Views: 595

### Re: Rounding atomic weight (general question)[ENDORSED]

In the test we will be given a periodic table and I would assume that we are meant to use whatever version of the atomic mass that the table specifies :)

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