Search found 32 matches

by David He
Wed Nov 18, 2020 4:15 am
Forum: Lewis Structures
Topic: Sampling #3
Replies: 2
Views: 19

Sampling #3

When drawing nitrate ion, I assume the Lewis structure with two O=N and one O-N is more stable than a structure with one O=N and two O-N, but only the latter one is assessed as correct. Why is that?
by David He
Sun Nov 15, 2020 11:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Find Periodic Table and Equation Sheet [ENDORSED]
Replies: 2
Views: 36

Find Periodic Table and Equation Sheet [ENDORSED]

Just want to know, where can we find the periodic table and equation sheet for midterm 2?
by David He
Sun Nov 15, 2020 11:21 am
Forum: Formal Charge and Oxidation Numbers
Topic: Clarification
Replies: 8
Views: 28

Re: Clarification

That is correct
by David He
Sun Nov 15, 2020 11:19 am
Forum: Lewis Structures
Topic: Lewis acid and Lewis bases
Replies: 8
Views: 43

Re: Lewis acid and Lewis bases

Lewis acid takes electron and Lewis base provides electron
by David He
Sun Nov 15, 2020 11:18 am
Forum: Lewis Structures
Topic: Oxidation Number
Replies: 4
Views: 24

Re: Oxidation Number

In the sampling question you can click "hint" on the top then you will get a link to explanation!
by David He
Sun Nov 15, 2020 11:16 am
Forum: Lewis Structures
Topic: Nitrite vs Nitrate
Replies: 17
Views: 78

Re: Nitrite vs Nitrate

I recommend you just google the formula of the element. I don't think we are required to infer structure by its name
by David He
Sun Nov 15, 2020 11:05 am
Forum: Lewis Structures
Topic: how to draw lewis structures w double bonds
Replies: 3
Views: 16

Re: how to draw lewis structures w double bonds

In short, it's better not to leave lone pair in the central atom because it will imply unstableness
by David He
Sun Nov 15, 2020 11:00 am
Forum: Lewis Structures
Topic: Sapling HW Q4
Replies: 9
Views: 67

Re: Sapling HW Q4

I am still having trouble understanding the difference between the terms "ample" and "overwhelmingly" bond character. I know that real structures are a blend of resonance structures, but I am unsure about how to connect this idea to the bond character. Any kind of clarification ...
by David He
Sun Nov 15, 2020 10:56 am
Forum: Lewis Structures
Topic: Drawing Lewis Structures on Midterm
Replies: 31
Views: 114

Re: Drawing Lewis Structures on Midterm

I suppose the exam will be multiple choice only, so you will not actually draw the structure.
by David He
Sun Nov 15, 2020 10:53 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Really helpful videos!
Replies: 4
Views: 122

Re: Really helpful videos!

Great video! I really appreciate that.
by David He
Sun Nov 15, 2020 10:53 am
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles
Replies: 16
Views: 219

Re: bond angles

bonding angle is determined by the number of atoms in a molecule and the arrangement of atoms
by David He
Sun Nov 15, 2020 10:46 am
Forum: Determining Molecular Shape (VSEPR)
Topic: The shape
Replies: 5
Views: 37

Re: The shape

There should not be any rigid rules for drawing atoms, because in reality, the site of atoms in a molecule can change slightly.
by David He
Sun Nov 15, 2020 10:40 am
Forum: Determining Molecular Shape (VSEPR)
Topic: lone pairs
Replies: 6
Views: 38

Re: lone pairs

First, we should know that lone pair makes an atom bigger, because electrons repel each other. If one pair of electron forms bonding, that means the electrons are attracted by other electrons, so they would no longer repel each other, making the size smaller. If you apply this idea, you will notice ...
by David He
Sun Nov 15, 2020 10:37 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion
Replies: 9
Views: 45

Re: Repulsion

Bonding pairs are attracted by two nuclei, which stabilizes the repelsion force.
by David He
Sun Nov 15, 2020 10:34 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone-Lone Pair vs Lone Bonding Pair vs Bonding-Bonding Pair?
Replies: 5
Views: 34

Re: Lone-Lone Pair vs Lone Bonding Pair vs Bonding-Bonding Pair?

First, we should know that lone pair makes an atom bigger, because electrons repel each other. If one pair of electron forms bonding, that means the electrons are attracted by other electrons, so they would no longer repel each other, making the size smaller. If you apply this idea, you will notice ...
by David He
Sun Nov 15, 2020 10:20 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling HW Q17
Replies: 5
Views: 41

Re: Sapling HW Q17

Hi, it confuses me too. Can anyone tell me how to determine the electronegativity of atoms?
by David He
Sun Nov 15, 2020 10:13 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Content of the final
Replies: 11
Views: 490

Re: Content of the final

What is bond order? when did we learn that?
by David He
Wed Nov 04, 2020 5:32 pm
Forum: Administrative Questions and Class Announcements
Topic: Accessing the E-textbook [ENDORSED]
Replies: 58
Views: 6210

Re: Accessing the E-textbook [ENDORSED]

I have purchased sampling access for 60 dollars or so, I believe that would be enough
by David He
Wed Nov 04, 2020 5:27 pm
Forum: Administrative Questions and Class Announcements
Topic: How to find my posts
Replies: 75
Views: 48910

Re: How to find my posts

You can scroll down to the bottom of the topic that you have replied, and there it is!
by David He
Wed Nov 04, 2020 5:25 pm
Forum: Administrative Questions and Class Announcements
Topic: Fall 2020 Midterm 1 Instructions
Replies: 20
Views: 1021

Re: Fall 2020 Midterm 1 Instructions

When will the score released, and where can we see them?
by David He
Wed Nov 04, 2020 5:23 pm
Forum: Administrative Questions and Class Announcements
Topic: Participation Points [ENDORSED]
Replies: 62
Views: 885

Re: Participation Points [ENDORSED]

Just want to be sure, do we have to post five posts each week, or it would be fine as long as we have 50 posts at the end of the quarter?
by David He
Sat Oct 24, 2020 9:04 am
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 196
Views: 821

Re: How are you studying?

Hi, I have made a schedule about when and for how long I should study each subject; it does help me to keep on track. Good luck to you!
by David He
Sat Oct 24, 2020 8:56 am
Forum: *Shrodinger Equation
Topic: Sapling week 2/3
Replies: 12
Views: 122

Re: Sapling week 2/3

Should we be able to answer this question already? If so does anyone know the steps to solve it? Any help would be great. Thanks! What is the minimum uncertainty in an electron's velocity (Δvmin) if the position is known within 15 Å. What is the minimum uncertainty in a helium atom's velocity (Δvmi...
by David He
Sat Oct 24, 2020 8:32 am
Forum: Administrative Questions and Class Announcements
Topic: Excellence in Chemistry Award!
Replies: 27
Views: 6839

Re: Excellence in Chemistry Award!

Congratulations!!!
by David He
Sat Oct 24, 2020 8:25 am
Forum: Administrative Questions and Class Announcements
Topic: Where can I buy a webcam for a reasonable price?
Replies: 60
Views: 916

Re: Where can I buy a webcam for a reasonable price?

Great question. I did not realize we need a webcam until I see this post. Sadly I don't know where to by a reasonably cheap webcam, but maybe I can sponsor you for $10 if you really like that $35 cam.
by David He
Sat Oct 10, 2020 8:55 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Names of Organic Compounds [ENDORSED]
Replies: 2
Views: 29

Re: Names of Organic Compounds [ENDORSED]

Hi, I don't know the equation of the compound either, but I was able to do the question, so I suppose knowing the exact equation of the compound is not necessary.
by David He
Sat Oct 10, 2020 8:53 am
Forum: Significant Figures
Topic: Sapling Question 2
Replies: 14
Views: 99

Re: Sapling Question 2

It should be positive, because 2.917 * 100 = 291,7
by David He
Sat Oct 10, 2020 8:51 am
Forum: Significant Figures
Topic: Significant Figures
Replies: 4
Views: 39

Re: Significant Figures

Hi, I think you are right. We don't do rounding during the calculation process; we only round the number when giving the result
by David He
Sat Oct 10, 2020 8:48 am
Forum: Administrative Questions and Class Announcements
Topic: Saying Thank You to Dr. Lavelle
Replies: 291
Views: 135756

Re: Saying Thank You to Dr. Lavelle

Thank you Dr. Lavelle for always doing your best to make chemistry fun. I'm glad I had the privilege to take your class. We appreciate all your hard work and thank you for everything you've provided us with throughout this quarter.

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