CHEMISTRY COMMUNITY

Celeste Martinez 1K

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?

Celeste Martinez 1K

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!

Celeste Martinez 1K

Award Recipient!

Celeste Martinez 1K

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.

Celeste Martinez 1K

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.

Celeste Martinez 1K

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!

Celeste Martinez 1K

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.

Celeste Martinez 1K

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!...

Celeste Martinez 1K

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...

Celeste Martinez 1K

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!

Celeste Martinez 1K

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!

Celeste Martinez 1K

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...

Celeste Martinez 1K

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.

Celeste Martinez 1K

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 ...

Celeste Martinez 1K

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...

Celeste Martinez 1K

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...

Celeste Martinez 1K

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?

Celeste Martinez 1K

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?

Celeste Martinez 1K

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.

Celeste Martinez 1K

On my notes, I have written that the DeBroglie equation does not apply to light since light doesn't contain mass.

Celeste Martinez 1K

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...

Celeste Martinez 1K

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).

Celeste Martinez 1K

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?

Celeste Martinez 1K

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?"

Celeste Martinez 1K

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!

Celeste Martinez 1K

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...

Celeste Martinez 1K

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).

Celeste Martinez 1K

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?

Celeste Martinez 1K

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!

Celeste Martinez 1K

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.

Celeste Martinez 1K

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.

CHEMISTRY COMMUNITY

Search found 31 matches

HW J9

Re: Bronsted vs Lewis acids

Re: Award Pictures [ENDORSED]

Re: Final [ENDORSED]

Re: HW 4.13 part c

Re: VSEPR AXE

Re: 4.3 Homework

Re: H Formal Charge

Re: Homework 3.39 part b

Re: negative charges and lewis structures

Re: Finding a Lewis Structure with the Lowest Energy

HW 3.49 Part E

Re: Relationship between Electronegativity and Ionization Energy

Re: question 8 week 5

Re: Ni3+

Re: Question 7 week 5

Re: Explanation to the answer of the question 2.31

Clarification on Spin Quantum Number

Re: 2.29

Re: When to use DeBroglie or Ek equation

Re: HW Problem 1.27

Re: Homework Questions for Week IV

Test 2 [ENDORSED]

Re: Lyman and Balmer Series

Re: work example in class from April 16

HW 1.5 [ENDORSED]

Re: HW 1.3 [ENDORSED]

HW 1.7 (speed of light) clarification

Re: Periodic Table Memorization [ENDORSED]

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

Re: Confusion about Significant Figures (F.5)