Search found 31 matches

by Celeste Martinez 1K
Thu Jun 07, 2018 6:39 pm
Forum: Lewis Acids & Bases
Topic: HW J9
Replies: 2
Views: 190

HW J9

In order to identify a strong acidic solution (hydrochloric acid), can we apply the "strong, short bonds are less acidic" and "weak, long bonds are more acidic."

Would image b be correct since the atoms are all over the place?
by Celeste Martinez 1K
Thu Jun 07, 2018 6:09 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs Lewis acids
Replies: 3
Views: 320

Re: Bronsted vs Lewis acids

A Bronsted acid is a proton donor while a Lewis acid accepts an electron pair.
A Bronsted base is a proton acceptor while a Lewis base donates an electron pair.

Hope this helped!
by Celeste Martinez 1K
Thu Jun 07, 2018 5:50 pm
Forum: Administrative Questions and Class Announcements
Topic: Award Pictures [ENDORSED]
Replies: 5
Views: 253

Re: Award Pictures [ENDORSED]

Award Recipient!
by Celeste Martinez 1K
Thu Jun 07, 2018 5:44 pm
Forum: General Science Questions
Topic: Final [ENDORSED]
Replies: 10
Views: 521

Re: Final [ENDORSED]

I believe the final is cumulative so I'm sure there will be a balance between pre-midterm and post-midterm material. This is what I heard from my UA. Correct me if I'm wrong.
by Celeste Martinez 1K
Thu May 31, 2018 9:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: HW 4.13 part c
Replies: 4
Views: 126

Re: HW 4.13 part c

The solutions manual states that there are other possible resonance forms so yours is right and the solutions manual's as well. It's just about which one is more stable but I don't think that matters when it comes to the shape of the molecule and bond angles.
by Celeste Martinez 1K
Thu May 31, 2018 9:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR AXE
Replies: 4
Views: 157

Re: VSEPR AXE

E in the VSEPR Formula is always referred to as 'PAIRED' lone electrons so I doubt you would put anything if there was a radical.

Hope this helped!
by Celeste Martinez 1K
Thu May 31, 2018 9:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 4.3 Homework
Replies: 3
Views: 140

Re: 4.3 Homework

Since the lone pair is on nitrogen and not the central atom (carbon), then the shape is linear for HCN. CH2N2 is tetrahedral because carbon (center atom) is bonded with 4 atoms. If it was trigonal planar, carbon would've been bonded with three atoms.
by Celeste Martinez 1K
Wed May 23, 2018 10:28 pm
Forum: Lewis Structures
Topic: H Formal Charge
Replies: 4
Views: 152

Re: H Formal Charge

I understand the formal charge would be zero. However, why don't we label it as such? When other atoms in the Lewis structure have a formal charge of zero we indicate it. Would it be wrong to include it? I don't think it'll be wrong to include it. If you feel like you have to include it, go for it!...
by Celeste Martinez 1K
Wed May 23, 2018 10:02 pm
Forum: Lewis Structures
Topic: Homework 3.39 part b
Replies: 2
Views: 128

Re: Homework 3.39 part b

Find the valence electrons for each atom and add them together. This will be the amount of electrons that should be present in the lewis structure of the molecule. Follow the octet rule (although there are some exceptions such as radicals), check formal charge, and go about making single, double, or...
by Celeste Martinez 1K
Wed May 23, 2018 9:54 pm
Forum: Ionic & Covalent Bonds
Topic: negative charges and lewis structures
Replies: 3
Views: 124

Re: negative charges and lewis structures

The outside charge is the charge of the whole molecule. This charge can be found by calculating the formal charge of every atom in the molecule and adding them together.

Hope this helped!
by Celeste Martinez 1K
Thu May 17, 2018 7:31 pm
Forum: Lewis Structures
Topic: Finding a Lewis Structure with the Lowest Energy
Replies: 5
Views: 182

Re: Finding a Lewis Structure with the Lowest Energy

What I do is make sure that every atom satisfies the octet rule and then calculate the formal charge, so I guess you can say it's mostly trial and error.

Hope this helped!
by Celeste Martinez 1K
Thu May 17, 2018 7:06 pm
Forum: Lewis Structures
Topic: HW 3.49 Part E
Replies: 1
Views: 75

HW 3.49 Part E

How do we know which atom receives the extra electron when a molecule has a negative charge. For example, on the homework problem 3.49 part e, we need to draw the lewis structure for CN- How do we know if carbon or nitrogen will receive that added electron? Does this have to do anything with electro...
by Celeste Martinez 1K
Thu May 17, 2018 6:53 pm
Forum: Electronegativity
Topic: Relationship between Electronegativity and Ionization Energy
Replies: 4
Views: 844

Re: Relationship between Electronegativity and Ionization Energy

I agree with Nandhini 1G. I believe that if an element has low ionization energy, it should also have low electronegativity since those trends are the same on the periodic table.
by Celeste Martinez 1K
Wed May 09, 2018 9:52 pm
Forum: Molarity, Solutions, Dilutions
Topic: question 8 week 5
Replies: 1
Views: 185

Re: question 8 week 5

a) Divide the 4.00 g of salt by the molar mass of CaCl2 (110.98 g/mol) = 0.036 mol of CaCl2. Since we only want the concentration of chloride ions, we multiply 0.036 mol of CaCl2 by the 2 moles of chloride ions which gives us 0.072 mol Cl/1 L. Concentration of chloride ions is 0.072 M. b) The total ...
by Celeste Martinez 1K
Wed May 09, 2018 9:18 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ni3+
Replies: 3
Views: 1477

Re: Ni3+

I'll still explain it, just in case someone else is confused: Nickel's (Ni) electron configuration is: [Ar] 3d^8 4s^2 Ni3+ means removing 3 electrons and when we do this, we have to take the electrons off from the highest energy, in this case, 4s. Since you can only take 2 electrons away from 4s, we...
by Celeste Martinez 1K
Wed May 09, 2018 9:05 pm
Forum: Molarity, Solutions, Dilutions
Topic: Question 7 week 5
Replies: 1
Views: 178

Re: Question 7 week 5

Molarity=moles of solute/volume of solution, so 0.30 M = 0.30 mol/1L. Since there are 5 liters after the nurse dilutes 1 L of the solution by adding 4 L of water, the equation becomes 0.30 mol/5 L= a concentration of 0.06 M. We then multiply this (0.06 mol/L) by 0.10 L (100 mL=0.10 L). The answer sh...
by Celeste Martinez 1K
Thu May 03, 2018 3:28 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Explanation to the answer of the question 2.31
Replies: 4
Views: 135

Re: Explanation to the answer of the question 2.31

I had the same question as to why 2d does not exist if 2s and 2p exist. Why does it stop at 2p and not continue?
by Celeste Martinez 1K
Thu May 03, 2018 3:18 pm
Forum: Quantum Numbers and The H-Atom
Topic: Clarification on Spin Quantum Number
Replies: 4
Views: 180

Clarification on Spin Quantum Number

I'm a bit confused about the spin quantum number in the sense of when we have to use it or state it? Does the up or down arrow affect the electrons in any way?
by Celeste Martinez 1K
Thu May 03, 2018 3:00 pm
Forum: Quantum Numbers and The H-Atom
Topic: 2.29
Replies: 9
Views: 390

Re: 2.29

Can someone explain part d from problem 2.29. since n=3 and l=2, I know that it is in the 3d shell. It then gives you the magnetic quantum number which is +1. The answer is 2 electrons, but I don't understand why it is 2 electrons. I thought the d sub shell could hold up to 10 electrons.
by Celeste Martinez 1K
Wed Apr 25, 2018 10:45 pm
Forum: DeBroglie Equation
Topic: When to use DeBroglie or Ek equation
Replies: 7
Views: 301

Re: When to use DeBroglie or Ek equation

On my notes, I have written that the DeBroglie equation does not apply to light since light doesn't contain mass.
by Celeste Martinez 1K
Wed Apr 25, 2018 10:33 pm
Forum: Einstein Equation
Topic: HW Problem 1.27
Replies: 1
Views: 169

Re: HW Problem 1.27

Since 1 W= 1 J/s and there are 32 W then you basically have 32 J/s. The problem is asking us for how many photons can be generated in 2 seconds. Therefore, we get 32*2= 64 J. In this case we will use the equation E=h*c/Lambda since we already have the wavelength (420 x 10^-9 m). Multiply Planck's co...
by Celeste Martinez 1K
Wed Apr 25, 2018 10:08 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Homework Questions for Week IV
Replies: 3
Views: 117

Re: Homework Questions for Week IV

The homework problems Dr. Lavelle sent us are to prepare us for test 2 and the topics that will show up on the test. However, you can still choose homework problems from another chapter (as long as we covered it in class).
by Celeste Martinez 1K
Thu Apr 19, 2018 9:17 pm
Forum: Properties of Light
Topic: Test 2 [ENDORSED]
Replies: 4
Views: 230

Test 2 [ENDORSED]

For test 2 and future tests/exams, are we suppose to memorize constants, conversions, or any formulas? Also for wavelength, which units are preferable, m or nm?
by Celeste Martinez 1K
Thu Apr 19, 2018 9:08 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Lyman and Balmer Series
Replies: 3
Views: 156

Re: Lyman and Balmer Series

I have the same question. Also, is there anyone that can explain problem 1.11 which asks "what is common to the lines within a series that makes grouping them together logical?"
by Celeste Martinez 1K
Thu Apr 19, 2018 9:00 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: work example in class from April 16
Replies: 2
Views: 83

Re: work example in class from April 16

The 1/16 comes from 1/4^2 which equal 1/16. This is done because the formula is E[n] = -hR/n^2 in order to not have that division sign, we can write it as E[n] = -1/n^2 * hR

Hope this helps!
by Celeste Martinez 1K
Thu Apr 12, 2018 3:00 am
Forum: Properties of Light
Topic: HW 1.5 [ENDORSED]
Replies: 7
Views: 295

HW 1.5 [ENDORSED]

The homework problem asks us to "arrange the following types of photons of electromagnetic radiation in order of increasing energy: y-rays, visible light, ultraviolet radiation, microwaves, x-rays" Are we suppose to look at an image/chart in order to figure this out or are we suppose to ca...
by Celeste Martinez 1K
Thu Apr 12, 2018 2:50 am
Forum: Properties of Light
Topic: HW 1.3 [ENDORSED]
Replies: 12
Views: 458

Re: HW 1.3 [ENDORSED]

C is correct because the lower the frequency, the longer the wavelength; therefore, causing it to have a decrease in the slope (extent of the change).
by Celeste Martinez 1K
Thu Apr 12, 2018 2:06 am
Forum: Properties of Light
Topic: HW 1.7 (speed of light) clarification
Replies: 4
Views: 135

HW 1.7 (speed of light) clarification

In lecture, I know that Dr. Lavelle mentioned that the speed of light was 3.0 x 10^8 but on the solutions manual, it says 2.998 x 10^8
Does it matter which one we use? Would the latter one be more accurate or preferable?
by Celeste Martinez 1K
Fri Apr 06, 2018 4:59 pm
Forum: Empirical & Molecular Formulas
Topic: Periodic Table Memorization [ENDORSED]
Replies: 8
Views: 400

Re: Periodic Table Memorization [ENDORSED]

No, we don't have to memorize the periodic table. I'm sure they will provide us with one or maybe put it on screen so the whole class can see it. If you need one, the UCLA Bookstore sells some. It is very nice to have your own copy for homework or tests!
by Celeste Martinez 1K
Fri Apr 06, 2018 4:32 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Which mass of oxygen should be used? [ENDORSED]
Replies: 23
Views: 961

Re: Which mass of oxygen should be used? [ENDORSED]

I'm sure you can use 16 grams/mol since Dr. Lavelle has used that in lectures. There's not much difference between 15.99 grams/mol and 16 grams/mol so I would go for the 16 since I'm sure rounding is preferred.
by Celeste Martinez 1K
Fri Apr 06, 2018 1:08 pm
Forum: SI Units, Unit Conversions
Topic: Confusion about Significant Figures (F.5)
Replies: 2
Views: 168

Re: Confusion about Significant Figures (F.5)

I also did problem F. 5 and what I did was round to the hundredths place. My answer at the end came out to be 100.2% so I'm guessing that's not a problem. Just disregard the extra significant figures and just round, in my opinion. The answer will be close to 100% anyways.

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