Search found 29 matches

by Myles Chang 1B
Wed Jun 13, 2018 12:16 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair=Polar?
Replies: 3
Views: 227

Re: Lone Pair=Polar?

This is not necessarily true. For example, XEF2 has two lone pairs, yet is still nonpolar and linear.
by Myles Chang 1B
Wed Jun 13, 2018 12:13 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Shapes [ENDORSED]
Replies: 1
Views: 166

Re: Determining Shapes [ENDORSED]

I think your confusion lies within the fact that in one explanation you are describing the general shape using regions of electron density whereas in the other you are referring to bonded atoms. For example, both bent and trigonal planar have three regions of electron density, however bent is called...
by Myles Chang 1B
Wed Jun 13, 2018 12:10 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs. Angular
Replies: 11
Views: 359

Re: Bent vs. Angular

Bent and angular describe the same shape. The VSEPR number would be AX2E
by Myles Chang 1B
Sun Jun 03, 2018 9:37 pm
Forum: Hybridization
Topic: Differences Between Pi and Sigma bonds
Replies: 7
Views: 223

Re: Differences Between Pi and Sigma bonds

I think Pi bonds differ from Sigma bonds in how they affect a molecule's structure. Pi bonds prevent a molecule from rotating, namely.
by Myles Chang 1B
Sun Jun 03, 2018 9:33 pm
Forum: Hybridization
Topic: Lone Pairs
Replies: 5
Views: 171

Re: Lone Pairs

I think the shape in general will stay the same just because of the areas of electron density, however the exact structure will not be identical. For example, the difference between a trigonal pyramidal and tetrahedral structure is the replacement of one lone pair of electrons with a bond. The bond ...
by Myles Chang 1B
Sun Jun 03, 2018 9:27 pm
Forum: Bond Lengths & Energies
Topic: HW question 4.1
Replies: 5
Views: 240

Re: HW question 4.1

The lone pair is above the central atom, not represented by any of the three circles in the diagram. The question is referring to the fact that the lone pairs above the central atom repelling the other electrons to create a bent shape.
by Myles Chang 1B
Sun Jun 03, 2018 9:24 pm
Forum: Hybridization
Topic: Textbook 4.37
Replies: 3
Views: 136

Re: Textbook 4.37

I think your confusion stems from the fact that the 2 lone electrons are found in one orbital, meaning that the P atom only has 4 regions of electron density.
by Myles Chang 1B
Sun Jun 03, 2018 9:21 pm
Forum: Bond Lengths & Energies
Topic: Test 3 Q 8 [ENDORSED]
Replies: 9
Views: 446

Re: Test 3 Q 8 [ENDORSED]

I think for this question it is important to note that resonance structures are not individualized possibilities of a structure, but rather are a blend of them. Looking at the Lewis dot diagram for the top image, you could put the two double bonds in various places, meaning that the actual length (a...
by Myles Chang 1B
Sun May 20, 2018 1:08 pm
Forum: Formal Charge and Oxidation Numbers
Topic: oxidation
Replies: 7
Views: 323

Re: oxidation

In general, elements closer to the left side of the periodic table (s-block and some of p-block) form cations because it is easier for them to lose, for example, 2 electrons in the case of Mg rather than gain 6. Likewise, it would require a lot of energy to pull 7 valence electrons away from a chlor...
by Myles Chang 1B
Sun May 20, 2018 1:02 pm
Forum: Octet Exceptions
Topic: 3.53 b
Replies: 1
Views: 94

Re: 3.53 b

I think the formal charges apply only to the atom, not the molecule. Otherwise, given that the two molecules have the same amount of electrons, wouldn't every single possible structure for a molecule have the same formal charge? The first structure's atoms all have formal charges of 0 whereas the se...
by Myles Chang 1B
Sun May 20, 2018 12:36 pm
Forum: Ionic & Covalent Bonds
Topic: Variable Valence
Replies: 1
Views: 74

Variable Valence

Hello!

I was wondering if there was any way to tell how many electrons in the d-block are lost in an ion. For example, is there any way to know whether a copper atom will go to 3+ or 2+; if there is not, will be be given the charge on the test?
by Myles Chang 1B
Sun May 13, 2018 9:31 pm
Forum: Lewis Structures
Topic: Ionic vs Covalent
Replies: 5
Views: 199

Re: Ionic vs Covalent

Covalent bonds form molecules and ionic bonds form ionic compounds. Ions are anything that have a net electric charge, which is why saying that ionic compounds are only made of metals and nonmetals is dangerous. For example, NH4+ and CO32- are both ions that can form an ionic bond with each other, b...
by Myles Chang 1B
Sun May 13, 2018 9:26 pm
Forum: Resonance Structures
Topic: How do Resonance Structures Work?
Replies: 4
Views: 204

How do Resonance Structures Work?

Hello!
I was a bit confused on how resonance structures work. Dr. Lavelle mentioned in class that the real structure of an element is not any of the resonance structures, but rather is an average of them. How does that work? How can one electron be spread across multiple, incomplete orbitals?
by Myles Chang 1B
Sun May 13, 2018 9:24 pm
Forum: Lewis Structures
Topic: Order of Dots
Replies: 11
Views: 407

Re: Order of Dots

There is no specific order that you need to fill in the dots. The only thing you need to be wary of is that Hund's rule needs to be applied. This means that you shouldn't have two electrons in one orbital (one side of the element), while another has zero.
by Myles Chang 1B
Mon May 07, 2018 12:48 am
Forum: Trends in The Periodic Table
Topic: Stability of Cl vs Cl-
Replies: 6
Views: 240

Re: Stability of Cl vs Cl-

Chlorine is very reactive because of how close it is to filling a full electron shell. Since it only needs only more to complete a shell as opposed to losing 7, Cl- is the most common form. This is also why we see Na+ a lot. The Na needs to lose an electron to have a full valence shell. Hence, NaCl.
by Myles Chang 1B
Mon May 07, 2018 12:45 am
Forum: Ionic & Covalent Bonds
Topic: Midterm Topics [ENDORSED]
Replies: 33
Views: 1916

Re: Midterm Topics [ENDORSED]

Will we need to be able to explain the existence of orbitals using the Heisenberg Uncertainity Principle or anything about the uncertainty principle for that matter?
by Myles Chang 1B
Mon May 07, 2018 12:43 am
Forum: Trends in The Periodic Table
Topic: Across vs Down Trend
Replies: 2
Views: 125

Across vs Down Trend

Hello! I had a question regarding whether an element's period or column had a larger influence on its atomic radius. For example, which would have a larger atomic radius: zinc or silver?
by Myles Chang 1B
Sun Apr 29, 2018 8:07 pm
Forum: *Shrodinger Equation
Topic: double derivative [ENDORSED]
Replies: 2
Views: 257

Re: double derivative [ENDORSED]

I believe that Dr. Lavelle said that we will not need to use the Schrodinger Equation on any tests, rather, his explanation provides some context as to how we know where electrons are.
by Myles Chang 1B
Sun Apr 29, 2018 8:04 pm
Forum: *Shrodinger Equation
Topic: ch.2.1
Replies: 5
Views: 253

Re: ch.2.1

Electrons are found in orbitals surrounding the nucleus. The positive charge of the protons in the nucleus attracts the negatively charged electrons.
by Myles Chang 1B
Sun Apr 29, 2018 8:02 pm
Forum: Properties of Light
Topic: Test #2: Q6 [ENDORSED]
Replies: 10
Views: 540

Re: Test #2: Q6 [ENDORSED]

I think this is most likely just a calculator error. You should get the same answer regardless of what equation you use.
by Myles Chang 1B
Sat Apr 21, 2018 12:26 pm
Forum: Photoelectric Effect
Topic: When to use Planck's Constant [ENDORSED]
Replies: 5
Views: 206

Re: When to use Planck's Constant [ENDORSED]

Use Planck's constant whenever you see the letter "h" in an equation you need to use on the sheet provided on top of the test.
by Myles Chang 1B
Sat Apr 21, 2018 12:17 pm
Forum: Properties of Electrons
Topic: electron mass
Replies: 15
Views: 574

Re: electron mass

It will make a difference on the test. I would guess at least a few of the calculations on the test will involve finding properties of an electron based on its momentum, which you need mass to find.
by Myles Chang 1B
Sat Apr 21, 2018 12:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Test Number 1
Replies: 10
Views: 460

Re: Test Number 1

I believe my TA said that the class could be curved but it wouldn't be until the end of the quarter.
by Myles Chang 1B
Mon Apr 16, 2018 1:15 pm
Forum: Properties of Light
Topic: Homework? [ENDORSED]
Replies: 10
Views: 370

Re: Homework? [ENDORSED]

I believe that if it has been covered in class, it is fair game to be chosen for hw. If you have a Tuesday discussion, you could also choose homework problems from Monday's lecture. Other than that, you should be able to do questions from Outline 1 as long as they are not repeated.
by Myles Chang 1B
Mon Apr 16, 2018 1:13 pm
Forum: Properties of Light
Topic: Photon units? [ENDORSED]
Replies: 4
Views: 129

Re: Photon units? [ENDORSED]

I think it's easiest to think of photons as little bundles of energy so therefore you would use joules to measure how much energy a photon has.
by Myles Chang 1B
Mon Apr 16, 2018 1:10 pm
Forum: Properties of Light
Topic: still don't uderrsatnd what a photon is [ENDORSED]
Replies: 20
Views: 411

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

A photon can also be a representation of a particle of light or other electromagnetic radiation.
by Myles Chang 1B
Sun Apr 08, 2018 1:58 pm
Forum: SI Units, Unit Conversions
Topic: writing out conversions in one long line vs. steps
Replies: 16
Views: 621

Re: writing out conversions in one long line vs. steps

I prefer to write out the expression in one long line to make sure my units line up, however, I do my calculations individually because I want to make sure that each of them make sense.
by Myles Chang 1B
Sat Apr 07, 2018 9:01 pm
Forum: Administrative Questions and Class Announcements
Topic: Test #1 [ENDORSED]
Replies: 4
Views: 208

Test #1 [ENDORSED]

Hi I'm not sure if this is where I should be asking this question or if this counts for one of our three posts but anyways I have some questions regarding the first exam this coming week. 1.) Will we have access to a periodic table or should we bring our own? 2.) For balancing equation problems, wil...
by Myles Chang 1B
Sat Apr 07, 2018 8:49 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.16 Part C
Replies: 2
Views: 111

G.16 Part C

For problem G.16 Part C, "Determine the mass of CuSO4 * 5H20 That must be used to prepare 250 mL of 0.20M CuSO4", does the water in the solute not show up as part of the final volume added to the 250 mL? The solution to the problem simply changes the molar mass of the solution when convert...

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