Search found 45 matches

by Emil Velasco 3I
Sun Nov 17, 2019 6:02 pm
Forum: Ionic & Covalent Bonds
Topic: Character of Bonds
Replies: 7
Views: 36

Re: Character of Bonds

Maddie wrote:Will he give us the actual electronegativity values on the tests though?


We won't be getting electronegativity values, so we have to know the trend on the periodic table.
by Emil Velasco 3I
Sun Nov 17, 2019 6:01 pm
Forum: Ionic & Covalent Bonds
Topic: London Dispersion
Replies: 13
Views: 52

Re: London Dispersion

Anokhi Patel 4G wrote:what exactly is london dispersion?


London dispersion is another name for Van der Waals forces, which is essentially really weak and temporary polarizations occurring due to the random movement of electrons in a molecule. It is the weakest intermolecular force and may occur on all molecules.
by Emil Velasco 3I
Sun Nov 17, 2019 5:59 pm
Forum: Lewis Structures
Topic: Carbon Monoxide
Replies: 4
Views: 17

Re: Carbon Monoxide

Having a triple bond in CO fulfills the octet rule for Carbon has Carbon would want to have an octet.

Satisfying the octet rule precedes Formal charges
by Emil Velasco 3I
Sun Nov 17, 2019 5:56 pm
Forum: Bond Lengths & Energies
Topic: Strongest Bonds
Replies: 9
Views: 35

Re: Strongest Bonds

Intermolecular strengths are: Ion-dipole, H-bond, Dipole-Dipole, Ion-induced dipole, Dipole-induced dipole, and London Forces
by Emil Velasco 3I
Sun Nov 17, 2019 5:54 pm
Forum: Octet Exceptions
Topic: Octet expansion
Replies: 6
Views: 17

Re: Octet expansion

Elements after the 3rd period may have expanded octets due to their access to the 3d subshell.
by Emil Velasco 3I
Sun Nov 17, 2019 5:52 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Calculating formal charge
Replies: 6
Views: 16

Re: Calculating formal charge

Doesn't matter where you start as long as the overall FC of the molecule matches what is given or is at the most favorable FC which is 0.
by Emil Velasco 3I
Sat Nov 09, 2019 10:17 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 9
Views: 53

Re: Formal Charge

You try to make the formal charge 0 where possible as long as the octet rule is satisfied. If not, you aim for the lowest energy structure possible that satisfies the octet rule, which involves having the lowest number of formal charges, especially with the central atom.
by Emil Velasco 3I
Sat Nov 09, 2019 10:16 pm
Forum: Octet Exceptions
Topic: octet exceptions
Replies: 11
Views: 72

Re: octet exceptions

Usually any element under the 3rd period may have an expanded octet due to having the whole of the d-block possible in their electron configuration
by Emil Velasco 3I
Sat Nov 09, 2019 10:14 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 17
Views: 60

Re: Resonance Structures

Resonance structures essentially combine into a resonance hybrid. Each resonance structure describes how possible delocalized electrons may form bonds.
by Emil Velasco 3I
Sat Nov 09, 2019 10:11 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 18
Views: 55

Re: Drawing Lewis Structures

When you draw Lewis structures, you just try to get the lowest energy structure possible, typically with a 0 formal charge where possible. If not, I think you just make the entire charge of the atom match what is given.
by Emil Velasco 3I
Sat Nov 09, 2019 10:09 pm
Forum: Ionic & Covalent Bonds
Topic: C, N, O, and F
Replies: 13
Views: 82

Re: C, N, O, and F

These four elements C, N, O, F follow the Octet guideline as they do not have access to the expanded octets found with the d block
by Emil Velasco 3I
Sun Nov 03, 2019 11:23 pm
Forum: DeBroglie Equation
Topic: When to use the DeBroglie equation?
Replies: 6
Views: 40

Re: When to use the DeBroglie equation?

I think you use De Broglie's for any time you are given any values toward the variables for conversions between them.
by Emil Velasco 3I
Sun Nov 03, 2019 11:21 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Order of removing electrons
Replies: 4
Views: 23

Re: Order of removing electrons

Once 4s is filled, it has a higher energy than the 3d orbital, so the electrons removed are from 4s, the outermost shell.
by Emil Velasco 3I
Sun Nov 03, 2019 11:20 pm
Forum: Trends in The Periodic Table
Topic: Midterm Question Regarding Metals, Nonmetals, etc
Replies: 2
Views: 16

Re: Midterm Question Regarding Metals, Nonmetals, etc

I think we just need to know how the concept relates to whatever question is being asked as opposed to actually naming them.
by Emil Velasco 3I
Sun Nov 03, 2019 11:17 pm
Forum: Trends in The Periodic Table
Topic: Does H have the highest ionization energy?
Replies: 4
Views: 29

Re: Does H have the highest ionization energy?

Flourine has the highest ionization energy, as it requires the most energy in order to lose an electron.

I believe Noble gases are excluded in this case but I'm not too sure.
by Emil Velasco 3I
Sun Nov 03, 2019 11:14 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Degenerate orbitals
Replies: 4
Views: 29

Re: Degenerate orbitals

"Degenerate" is just a term used to describe the spdf orbitals having the same energy; This applies to a single-electron atom like Hydrogen.

I'm not sure if this was mentioned in lecture but I know for sure that it was mentioned at a review session
by Emil Velasco 3I
Sun Nov 03, 2019 11:11 pm
Forum: Properties of Electrons
Topic: Photoelectric effect
Replies: 5
Views: 43

Re: Photoelectric effect

Khan Academy and the module were extremely helpful in understanding the topic!
by Emil Velasco 3I
Sun Oct 27, 2019 9:05 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Useful YouTube videos?
Replies: 6
Views: 29

Re: Useful YouTube videos?

Khan Academy's article was really helpful in explaining the building-up principle.
by Emil Velasco 3I
Sun Oct 27, 2019 9:03 pm
Forum: Trends in The Periodic Table
Topic: Ionization energy
Replies: 12
Views: 63

Re: Ionization energy

I don't think we have to know the actual equation but rather just the general trend of Ionization Energy in the periodic table.
by Emil Velasco 3I
Sun Oct 27, 2019 12:21 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: HW 1D.23
Replies: 4
Views: 53

Re: HW 1D.23

For part c, when n=2, it has 2s and 2p are valid orbitals

in which 2s contains 1 subshell orbital (mL=0) and 2p contains 3 subshell orbitals (mL=-1,0,+1)
by Emil Velasco 3I
Sun Oct 20, 2019 11:06 pm
Forum: Einstein Equation
Topic: When do we use the Einstein Equation?
Replies: 12
Views: 91

Re: When do we use the Einstein Equation?

E = hv is used to solve for the energy of an electron.

Sometimes you are not given v (frequency) therefore you must use c = λν, substituting the v in E=hv for v = c/ λ:

so E = hc/ λ
by Emil Velasco 3I
Sun Oct 20, 2019 11:04 pm
Forum: Photoelectric Effect
Topic: Speed of Light
Replies: 29
Views: 121

Re: Speed of Light

The speed of light is constant at 2.998x10^8 m.s^-1
by Emil Velasco 3I
Sun Oct 20, 2019 11:03 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: What does the H mean?
Replies: 9
Views: 43

Re: What does the H mean?

h is Planck's constant but h-bar is h/2pi
by Emil Velasco 3I
Sun Oct 20, 2019 4:23 pm
Forum: Properties of Light
Topic: N levels
Replies: 8
Views: 45

Re: N levels

n levels are just the levels of energy for an electron in which n is a quantum number (n=1,2,3, etc.). When electrons increase in energy, the n increases.
by Emil Velasco 3I
Sun Oct 20, 2019 4:20 pm
Forum: Properties of Electrons
Topic: Equations for Test
Replies: 9
Views: 54

Re: Equations for Test

I think all the equations are given to us, but we just have to know when to use them.
by Emil Velasco 3I
Sun Oct 20, 2019 4:19 pm
Forum: DeBroglie Equation
Topic: De Broglie's Equation
Replies: 17
Views: 76

Re: De Broglie's Equation

Photons do not have mass, only momentum.
by Emil Velasco 3I
Sat Oct 19, 2019 6:30 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Homework Problem 1B.27
Replies: 6
Views: 59

Re: Homework Problem 1B.27

We use 10 for delta V
by Emil Velasco 3I
Sat Oct 19, 2019 6:26 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: HW 1B #27
Replies: 2
Views: 18

Re: HW 1B #27

I used 5.00 value for delta v

Edit: Do not use 5.00 value for delta V:

Lavelle addressed this in his solution manual so we use 10 as delta v
https://lavelle.chem.ucla.edu/wp-conten ... rs_7Ed.pdf
by Emil Velasco 3I
Wed Oct 16, 2019 9:19 am
Forum: Properties of Light
Topic: Next test
Replies: 23
Views: 151

Re: Next test

I think we get an equation sheet
by Emil Velasco 3I
Sat Oct 12, 2019 9:18 pm
Forum: Einstein Equation
Topic: Numbers to memorize [ENDORSED]
Replies: 37
Views: 997

Re: Numbers to memorize [ENDORSED]

Helps a lot to memorize when you're doing practice problems but if you forget, there's always a cheat sheet he puts on the test for us to look at with all the constants!
by Emil Velasco 3I
Sat Oct 12, 2019 9:17 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7610
Views: 1020390

Re: Post All Chemistry Jokes Here

Studying chem has shown me a lot of funny jokes

He He He
by Emil Velasco 3I
Sat Oct 12, 2019 9:15 pm
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 166
Views: 100983

Re: Rusty on High School Chem [ENDORSED]

I'm also really rusty but so far I think doing the practice problems he has on his Course Outlines (from the 14A website) have been extremely helpful in getting exposed to practice problems. His modules have also helped me a ton in understanding some things I haven't touched up on since 4 years ago!
by Emil Velasco 3I
Sat Oct 12, 2019 9:12 pm
Forum: Properties of Light
Topic: Quantum Levels
Replies: 9
Views: 56

Re: Quantum Levels

I think there's a limit to how far an atom can be from the nucleus before it is lost as a "free electron."
I'm honestly not entirely sure though.
by Emil Velasco 3I
Sat Oct 12, 2019 9:10 pm
Forum: Photoelectric Effect
Topic: Planck's Constant
Replies: 4
Views: 58

Re: Planck's Constant

Online it says that he was able to derive this constant from experimental measurements from black-body radiation.
by Emil Velasco 3I
Sat Oct 12, 2019 9:05 pm
Forum: Einstein Equation
Topic: E=hv
Replies: 8
Views: 58

Re: E=hv

h = Planck's constant (6.626*10^-34 J*s)

It'll be given to us on the front sheet of a test with all the constants, I think
by Emil Velasco 3I
Sat Oct 12, 2019 9:00 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 41
Views: 796

Re: Speed of Light

The speed of light (3. 10^8 m/s) will always be a constant.
by Emil Velasco 3I
Sat Oct 12, 2019 8:59 pm
Forum: Properties of Electrons
Topic: wavelike properties of an electron
Replies: 4
Views: 40

Re: wavelike properties of an electron

The detectors sense that the electrons had shifted to other points as opposed to a single point due to diffraction, which is demonstrated through the electron's wave-like properties.
by Emil Velasco 3I
Sat Oct 12, 2019 8:56 pm
Forum: DeBroglie Equation
Topic: Concept of a wave
Replies: 7
Views: 57

Re: Concept of a wave

Also I believe wavelike properties are only demonstrated by objects that are extremely small.

While light does exhibit wavelike properties, the equation cannot be applied towards it.
by Emil Velasco 3I
Sat Oct 12, 2019 8:53 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 1896

Re: Test 1 [ENDORSED]

My TA said the test would be graded the same day so the grades might be up on ccle?
by Emil Velasco 3I
Thu Oct 10, 2019 12:01 am
Forum: Molarity, Solutions, Dilutions
Topic: L37
Replies: 3
Views: 50

L37

(a) How would you prepare 1.00 L of 0.50 M HNO3 (aq) from “concentrated” (16 M) HNO3 (aq)?

(b) How many milliliters of 0.20 M NaOH(aq) could be neutralized by 100. mL of the diluted solution?

I'm not entirely sure how to begin solving this problem
by Emil Velasco 3I
Thu Oct 03, 2019 11:27 pm
Forum: SI Units, Unit Conversions
Topic: Sig Fig Mistakes
Replies: 17
Views: 127

Re: Sig Fig Mistakes

I think you round the answer's sig fig to the smallest number at the calculation
by Emil Velasco 3I
Thu Oct 03, 2019 11:23 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's Number?
Replies: 16
Views: 118

Re: Avogadro's Number?

Do you think we will have to memorize the Avogadro's Number for test? I am wondering if I will be given the Avogadro's Number when I get the questions that ask for atoms' number. I don't think we need to memorize the number for the test, I think Lavelle mentioned having a front sheet on tests with ...
by Emil Velasco 3I
Thu Oct 03, 2019 11:19 pm
Forum: Empirical & Molecular Formulas
Topic: What decimal place to round to when taking masses from the Periodic Table?
Replies: 19
Views: 120

Re: What decimal place to round to when taking masses from the Periodic Table?

Personally I use two to three decimal places but I feel like in test, we should use all of the decimals for extra accuracy in our calculation
by Emil Velasco 3I
Thu Oct 03, 2019 11:17 pm
Forum: Significant Figures
Topic: How would sig figs be used in a problem?
Replies: 7
Views: 29

How would sig figs be used in a problem?

Would they ask "How many significant figures are in this number?"

I think I'm just confused about how this would be used practically in a problem?
by Emil Velasco 3I
Thu Oct 03, 2019 11:13 pm
Forum: SI Units, Unit Conversions
Topic: which unit to use
Replies: 9
Views: 99

Re: which unit to use

I think we just use the ones called for by the problem

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