Search found 50 matches

by Megan Ngai- 3B
Sat Dec 07, 2019 3:23 pm
Forum: Naming
Topic: Transition Metal Latin Names
Replies: 3
Views: 52

Re: Transition Metal Latin Names

iron and copper
by Megan Ngai- 3B
Sun Dec 01, 2019 12:30 am
Forum: Student Social/Study Group
Topic: Test 2 and Final
Replies: 18
Views: 213

Re: Test 2 and Final

My TA gave me my test before thanksgiving and the final should be cumulative
by Megan Ngai- 3B
Sun Dec 01, 2019 12:28 am
Forum: Administrative Questions and Class Announcements
Topic: Difficulty
Replies: 14
Views: 153

Re: Difficulty

Despite taking AP chem, this call has still been difficult. It covers topics more in depth than what I learnt in high school.
by Megan Ngai- 3B
Sun Dec 01, 2019 12:27 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Sigma and Pi Bonds
Replies: 12
Views: 509

Re: Sigma and Pi Bonds

1 sigma and 2 pi bonds
by Megan Ngai- 3B
Sun Dec 01, 2019 12:25 am
Forum: Student Social/Study Group
Topic: Final Preparation
Replies: 2
Views: 44

Re: Final Preparation

It should be everything we’ve learnt this quarter
by Megan Ngai- 3B
Sun Dec 01, 2019 12:23 am
Forum: Administrative Questions and Class Announcements
Topic: Final Exam Content
Replies: 14
Views: 138

Re: Final Exam Content

Cumulative!
by Megan Ngai- 3B
Sun Dec 01, 2019 12:22 am
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Grades
Replies: 10
Views: 149

Re: Test 2 Grades

They’re on MyUcla and my TA gave them back during my discussion before thanksgiving
by Megan Ngai- 3B
Sun Dec 01, 2019 12:21 am
Forum: Student Social/Study Group
Topic: Preparing for the final
Replies: 25
Views: 269

Re: Preparing for the final

The TA review sessions and reading the textbook helped a lot for me!
by Megan Ngai- 3B
Sun Nov 24, 2019 10:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs linear
Replies: 56
Views: 733

Re: Bent vs linear

bent has a lone pair while linear does not
by Megan Ngai- 3B
Thu Nov 21, 2019 3:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: test 2
Replies: 3
Views: 59

Re: test 2

^ retweet
by Megan Ngai- 3B
Thu Nov 21, 2019 3:07 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs linear
Replies: 56
Views: 733

Re: Bent vs linear

Bent has a lone pair while linear does not.
by Megan Ngai- 3B
Thu Nov 21, 2019 3:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: tetrahedral vs. trigonal pyramidal
Replies: 4
Views: 38

Re: tetrahedral vs. trigonal pyramidal

They are not the same. They both have four regions of electron density. However, tetrahedral has zero lone pairs which tribal pyramidal has one lone pair.
by Megan Ngai- 3B
Thu Nov 21, 2019 3:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: electron-pair geometry vs molecular geometry
Replies: 3
Views: 40

Re: electron-pair geometry vs molecular geometry

Electron pair geometry: number of regions of electron density
Molecular geometry: includes bonding pairs and lone pairs.
by Megan Ngai- 3B
Sat Nov 16, 2019 3:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T Shape
Replies: 7
Views: 66

Re: T Shape

It'll be safe to memorize them all
by Megan Ngai- 3B
Sat Nov 16, 2019 3:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sulfite Ion example in class
Replies: 6
Views: 34

Re: Sulfite Ion example in class

The lone pair creates an electron electron repulsion. Therefore, it'll push the bonded atoms away from it but push them closer to each other.
by Megan Ngai- 3B
Sat Nov 16, 2019 3:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing Molecular Structures
Replies: 8
Views: 58

Re: Drawing Molecular Structures

Lavelle said to just know how to name them.
by Megan Ngai- 3B
Sat Nov 16, 2019 3:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 3
Views: 35

Re: VSEPR

I just follow this chart!
by Megan Ngai- 3B
Sun Nov 10, 2019 3:33 pm
Forum: Bond Lengths & Energies
Topic: Strongest Bond
Replies: 15
Views: 128

Re: Strongest Bond

strongest to weakest is: covalent, ionic, hydrogen, dipole-dipole, london dispersion forces.

Bonds are stronger when they are shorter and have a higher bond order too.
by Megan Ngai- 3B
Sun Nov 10, 2019 3:32 pm
Forum: Trends in The Periodic Table
Topic: atomic radius
Replies: 7
Views: 137

Re: atomic radius

It decreases across the periodic table because there are more protons so there’s a strong nuclear charge pull.
by Megan Ngai- 3B
Sun Nov 10, 2019 3:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 7
Views: 71

Re: Test 2

It should pick up from after 2D
by Megan Ngai- 3B
Sun Nov 10, 2019 3:30 pm
Forum: Electronegativity
Topic: Periodic Trend
Replies: 13
Views: 130

Re: Periodic Trend

Electronegativity increases up groups then across periods.
by Megan Ngai- 3B
Sun Nov 10, 2019 3:26 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum numbers
Replies: 12
Views: 265

Re: Quantum numbers

The angular momentum is the l.
by Megan Ngai- 3B
Thu Oct 31, 2019 6:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 16
Views: 155

Re: Midterm

Yes, everything up to 2D!
by Megan Ngai- 3B
Thu Oct 31, 2019 6:54 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 11
Views: 89

Re: Electronegativity

It is how strongly an atom will attract electrons. So as you go across the period increase and as you go down a group it decreases.
by Megan Ngai- 3B
Thu Oct 31, 2019 6:50 pm
Forum: DeBroglie Equation
Topic: When to use the de Broglie equation?
Replies: 5
Views: 93

Re: When to use the de Broglie equation?

Whenever there is a mass given.
The equation E=hv and c=(wavelength)v would be specifically for light since c is used.
by Megan Ngai- 3B
Thu Oct 31, 2019 6:47 pm
Forum: Ionic & Covalent Bonds
Topic: Chemical Formula by expected charges
Replies: 2
Views: 23

Re: Chemical Formula by expected charges

If you look up periodic table charges on Google images, it shows the charges per group (it's easy to remember). So Mg has a charge of +2 and As has a charge of -3. Therefore it would be Mg3As2.
by Megan Ngai- 3B
Thu Oct 31, 2019 6:41 pm
Forum: Properties of Electrons
Topic: Atomic Spectra
Replies: 2
Views: 53

Re: Atomic Spectra

During the midterm review session, she said we most likely don't need to memorize it but just to somewhat know visible light and gamma rays (if I remember correctly).
by Megan Ngai- 3B
Sun Oct 27, 2019 12:50 am
Forum: Trends in The Periodic Table
Topic: atomic Radii
Replies: 11
Views: 91

Re: atomic Radii

yes! the more electrons means a larger radii because there will essentially be more shells.
by Megan Ngai- 3B
Sun Oct 27, 2019 12:47 am
Forum: Ionic & Covalent Bonds
Topic: Resonance
Replies: 12
Views: 134

Re: Resonance

Resonance involves delocalized electrons. That means fewer repulsions and more stability with a larger volume.
by Megan Ngai- 3B
Sun Oct 27, 2019 12:46 am
Forum: Ionic & Covalent Bonds
Topic: How are lewis structures filled?
Replies: 6
Views: 57

Re: How are lewis structures filled?

The first thing is that the atoms must follow the octet rule. Distribute the electrons one by one
by Megan Ngai- 3B
Sun Oct 27, 2019 12:45 am
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 11
Views: 140

Re: Midterm

November 6th! As for the format it should be like the last test?
by Megan Ngai- 3B
Sun Oct 27, 2019 12:45 am
Forum: Ionic & Covalent Bonds
Topic: Cation
Replies: 23
Views: 318

Re: Cation

Cations are atoms lost an electron so it has a positive charge.Anions are atoms that have gained an electron so it has a negative charge.
They're important because some elements are more stable as ions because they can gain their octet by gaining or losing an electron.
by Megan Ngai- 3B
Thu Oct 17, 2019 2:28 pm
Forum: Molarity, Solutions, Dilutions
Topic: What is Molarity?
Replies: 11
Views: 348

Re: What is Molarity?

Molarity is moles per liters, referring to the concentration of atoms/molecules in a solvent.
by Megan Ngai- 3B
Thu Oct 17, 2019 2:27 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: how to express answer
Replies: 6
Views: 39

Re: how to express answer

In class, Prof Lavelle ended with a = sigg. I'm pretty sure he said it was just simpler than writing greater than or equal to.
by Megan Ngai- 3B
Thu Oct 17, 2019 2:23 pm
Forum: Properties of Light
Topic: Speed of light
Replies: 13
Views: 113

Re: Speed of light

Electromagnetic radiation moves at the speed of light

Because the calc is about a type of light, c= 3x10^-8 m/s is used.
by Megan Ngai- 3B
Thu Oct 17, 2019 2:19 pm
Forum: DeBroglie Equation
Topic: De Broglie's Equation
Replies: 17
Views: 198

Re: De Broglie's Equation

De Broglie's equation requires an object to have a mass
wavelength = h/mv
by Megan Ngai- 3B
Thu Oct 17, 2019 2:16 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Spin State
Replies: 17
Views: 122

Re: Spin State

Spinning up is positive (+1/2)
Spinning down is negative -1/2
by Megan Ngai- 3B
Fri Oct 11, 2019 2:47 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 58
Views: 1865

Re: Study Tips

I personally read the textbook and take notes before lectures so the ideas will be explained again in different rooms. Whenever I have other questions I come to chemistry community and there are usually people who are having the same questions!
by Megan Ngai- 3B
Fri Oct 11, 2019 2:45 pm
Forum: Significant Figures
Topic: Sig Figs in % Yield
Replies: 10
Views: 285

Re: Sig Figs in % Yield

It would round up toe 64%, the next whole number
by Megan Ngai- 3B
Fri Oct 11, 2019 2:42 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Accuracy and Precision
Replies: 8
Views: 217

Re: Accuracy and Precision

It will usually apply to when you do labs or collect data.
Accuracy is how close your data is to the true value while precision is how close your data is to each other. Your data can be precise but not accurate.
by Megan Ngai- 3B
Fri Oct 11, 2019 2:40 pm
Forum: Significant Figures
Topic: Sig Figs in Answer
Replies: 8
Views: 220

Re: Sig Figs in Answer

For calculating mass % I usually do four sig figs ex: 56.78%
For molar mass I would do four sig figs after the decimal points ex; 12.3456
by Megan Ngai- 3B
Tue Oct 01, 2019 11:08 pm
Forum: Molarity, Solutions, Dilutions
Topic: HW E9 Part B
Replies: 4
Views: 86

Re: HW E9 Part B

1. you need to find the amount of moles in 5.51g.
- you divide 5.51g by the molar mass of the compound, 24.48
2. multiply by Avogadro's constant (6.022 x 10^23)
- the units of moles will cancel out and you are left with formula units!
by Megan Ngai- 3B
Tue Oct 01, 2019 11:05 pm
Forum: Significant Figures
Topic: Rounding the elements
Replies: 12
Views: 150

Re: Rounding the elements

I typically use the exact numbers that are given on the periodic table. This can prevent your answer from being a little off.
by Megan Ngai- 3B
Tue Oct 01, 2019 11:01 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's Number [ENDORSED]
Replies: 12
Views: 224

Re: Avogadro's Number [ENDORSED]

When you want to convert from moles to atoms, you multiply the molar amount by Avogadro’s number.
When you want to convert from atoms to moles, divide the atom amount by Avogadro’s number.
by Megan Ngai- 3B
Tue Oct 01, 2019 10:54 pm
Forum: Significant Figures
Topic: E1 Sig Figs
Replies: 4
Views: 89

Re: E1 Sig Figs

When trying to figure out sig figs, you should always look at the original question to figure out how many sig figs will be in your answer. In your example, there were the numbers 1.00 mol Ag atoms and the number 144 pm. Both of those numbers have 3 sig figs. The answer would not be 2 x 10^14 becaus...
by Megan Ngai- 3B
Tue Oct 01, 2019 10:50 pm
Forum: Significant Figures
Topic: Sig Figs in homework problems
Replies: 4
Views: 81

Re: Sig Figs in homework problems

For example, the problem had the numbers 3.45g and 100.79 g.

You should base the number of sig figs on the original problem. Even if you used a the atomic mass of 1.008 for hydrogen in your calculations, the sig figs should be based on 3.45g (3 sig figs) not 100.79 or 1.008.

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