## Search found 32 matches

- Thu Nov 07, 2019 7:13 pm
- Forum: Lewis Structures
- Topic: Expanded Octet
- Replies:
**9** - Views:
**41**

### Re: Expanded Octet

how can we know if they're likely to use the expanded octect though?

- Thu Nov 07, 2019 7:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: What homework to turn in per week
- Replies:
**7** - Views:
**43**

### Re: What homework to turn in per week

Jessica Tran_3K wrote:I also agree ^^ I think as long as the concept is still relevant, it should be fine.

So we're still good to do stuff from chemical bonds this week? I'm never sure about what we can do.

- Wed Nov 06, 2019 4:38 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing Power (Trends)
- Replies:
**3** - Views:
**39**

### Re: Polarizing Power (Trends)

As anions get larger and larger, their polarizability increases. This is due to the decreasing effective nuclear charge on their valence electrons. As charge increases on cations and as they get smaller, their polarizing power increases since they can get close to the nucleus of anions and exert a ...

- Mon Nov 04, 2019 6:38 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: initial and final variables
- Replies:
**4** - Views:
**36**

### Re: initial and final variables

Which ones are initial and which ones are final don't really matter, what matters is that the correct molarity is paired with the correct volume :)

- Mon Nov 04, 2019 6:37 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Textbook question
- Replies:
**3** - Views:
**52**

### Re: Textbook question

Chem_Mod wrote:I'm assuming c is concentration (ie Molarity), M is also molarity, n= number of moles, and v= volume. Can you elaborate on what "m" refers to?

I would assume that m is mass from the equation, since mass * molarity would result in n, the number of moles

- Thu Oct 31, 2019 9:27 pm
- Forum: Resonance Structures
- Topic: Homework 2C 1
- Replies:
**3** - Views:
**19**

### Re: Homework 2C 1

a radical is if a compound has an unpaired lone pair electron. radicals tend to be very reactive (due to them being unstable, often one electron away from a full valence shell)

- Thu Oct 31, 2019 9:23 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charges on Atoms Summed in Ions?
- Replies:
**6** - Views:
**22**

### Re: Formal Charges on Atoms Summed in Ions?

Kelvin Chung 1C wrote:In an ion, generally the formal charges should add up to the charge of the ion. In a molecule, I believe the formal charges should add up to 0.

exactly. for example Na has a formal charge of +1 and Cl has a formal charge of -1. Their combined compound NaCl has a formal charge of zero.

- Thu Oct 31, 2019 7:06 pm
- Forum: Octet Exceptions
- Topic: Radicals: Homework Problem #2C1
- Replies:
**8** - Views:
**32**

### Re: Radicals: Homework Problem #2C1

Jorge Ramirez_4H wrote:Are radicals that important for the midterm?

I'd like to know this as well. Will we be expected to select what compounds are radicals or not? And does this knowledge have some other application?

- Thu Oct 31, 2019 7:03 pm
- Forum: Ionic & Covalent Bonds
- Topic: Chemical Formula by expected charges
- Replies:
**2** - Views:
**16**

### Re: Chemical Formula by expected charges

Megan Ngai- 3B wrote: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.

Oh, this is super useful! Do you know where the formal charge comes from?

- Thu Oct 31, 2019 6:36 pm
- Forum: Ionic & Covalent Bonds
- Topic: Chemical Formula by expected charges
- Replies:
**2** - Views:
**16**

### Chemical Formula by expected charges

for 2A.23, it asks to give the chemical formula based on the charges of the elements involved in the compounds. How do you know what the charge is in order to calculate this? In the problem, it asks to give the formula for magnesium arsenide, so if that can be used as an example, it'd be helpful.

- Wed Oct 23, 2019 2:27 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Self-test 1E.2B
- Replies:
**2** - Views:
**15**

### Re: Self-test 1E.2B

[Ar]3d

^{10}4s^{2}4p^{3}, remembering to write 3d10 before 4s even though it comes after, because 3d10 is a lower energy level.- Wed Oct 23, 2019 2:22 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 4s and 3d
- Replies:
**5** - Views:
**35**

### Re: 4s and 3d

Emma Popescu 3D wrote:The 4s is filled first because it is at a lower energy than 3d. However, Dr. Lavelle wants us to put them from lowest to highest energy level (3d and then 4s) because 4s is ionized first.

ok so, 4s is filled first, and 3d is written first? thanks.

- Wed Oct 23, 2019 1:21 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals 1D.19
- Replies:
**3** - Views:
**52**

### Re: Orbitals 1D.19

First of all, s-subshell is l=0, p-subshell is l=1, d-subshell is l=2, f-subshell is l=3 For (a), it is 4p-subshell, so l= 1. If l=1, ml can be -1, 0, 1. Therefore, 4p-subshell can have 3 orbitals. For (b), it is 3d-subshell, so l=2. If l=2, ml can be -2, -1, 0, 1, 2. Therefore, 3d-subshell can hav...

- Wed Oct 23, 2019 12:59 am
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy Across a Period
- Replies:
**3** - Views:
**14**

### Re: Ionization Energy Across a Period

it's easier to think about whether an elememt wants to gain or lose an electron to become stable. elements in group 1 and 2 want to lose their electrons to become stable so the ionization energy is low. elements in groups further along the period are closer to becoming stable (filling their electron...

- Wed Oct 23, 2019 12:43 am
- Forum: Quantum Numbers and The H-Atom
- Topic: 1D.1
- Replies:
**5** - Views:
**41**

### Re: 1D.1

Mariah wrote:Im kind of confused about this, what would cause an electron to transition into a higher energy level in the first place? Do they do this on their own or because of some outside force?

they can get excited by light, and the energy from the photon allows them to make the transition.

- Thu Oct 17, 2019 10:51 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Homework Problem 1B.27
- Replies:
**6** - Views:
**57**

### Re: Homework Problem 1B.27

When doing your calculation, the Δv you should use is 10m/s, which is your maximum uncertainty. Why do we have to use the maximum uncertainty velocity in the Heisenberg Indeterminacy equation? because the maximum uncertainty is the entire range that you are uncertain. when you say plus or minus fiv...

- Thu Oct 17, 2019 9:57 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Radius
- Replies:
**4** - Views:
**36**

### Re: Atomic Radius

To add on, atomic radius increases down a group with each new period because the outermost electrons occupy shells with increasing principal quantum number and therefore lie farther from the nucleus. Atomic radius decreases across a period because new electrons are in the same shell of the atom and...

- Wed Oct 16, 2019 2:44 am
- Forum: Properties of Electrons
- Topic: Question about diffraction patterns
- Replies:
**3** - Views:
**22**

### Re: Question about diffraction patterns

I would recommend checking out the crash course video "Light Is Waves: Crash Course Physics #39" . The entire video is very helpful.

https://www.youtube.com/watch?v=IRBfpBPELmE&t=

https://www.youtube.com/watch?v=IRBfpBPELmE&t=

- Wed Oct 16, 2019 2:39 am
- Forum: Properties of Electrons
- Topic: Equations and confused of when to use what
- Replies:
**3** - Views:
**24**

### Re: Equations and confused of when to use what

So primarily talking about the E= hv, c= λv, r = h/n^2, Ek = 1/2mv^2, λ = h/mv So in essence, ryberg equation, energy of a photon equation, speed of light equation, de broglies, etc. When do we use such equations? Which equations should I primarily memorize or understand the most? What are the spec...

- Wed Oct 16, 2019 2:19 am
- Forum: Properties of Light
- Topic: Defraction patters
- Replies:
**3** - Views:
**36**

### Re: Defraction patters

I am a bit confused about diffraction patters and wavelike properties. Do both light and electrons have wave like properties? If so, does that mean they both have Difraction patterns. Also, what are diffraction patters? ok so basically, light/electrons acting as waves means that there will be some ...

- Fri Oct 11, 2019 12:10 am
- Forum: DeBroglie Equation
- Topic: How to know which equation to use
- Replies:
**9** - Views:
**100**

### Re: How to know which equation to use

505106414 wrote:What is a real-world application of this equation?

the v for frequency is actually nu (fun fact), and this is used to calculate wavelength, where c=lambda*v.

- Fri Oct 11, 2019 12:02 am
- Forum: Properties of Light
- Topic: HW 1.A #11
- Replies:
**4** - Views:
**47**

### Re: HW 1.A #11

Doris Cho 1D wrote:Not sure what the question is even asking... I understand what the answer is saying but I don't understand the question (?) if anyone knows what I mean...

it's asking how the lines are related, in this case it's asking you to make a connection the the energy levels

- Thu Oct 10, 2019 11:50 pm
- Forum: Properties of Light
- Topic: HW 1.A #9
- Replies:
**3** - Views:
**42**

### Re: HW 1.A #9

I matched up the right radiation to each event but I only figured out the 3.3 x 10^-19 J to microwaves because of process of elimination... does it need to be converted to Hz or nm for me to see that it goes with microwaves? I've seen charts with Hz or m but never any with Joules, so that might be ...

- Thu Oct 10, 2019 5:05 pm
- Forum: Properties of Light
- Topic: "Work Function" (from Post-Assessment Module)
- Replies:
**4** - Views:
**41**

### Re: "Work Function" (from Post-Assessment Module)

Chem_Mod answered your question already but if you want the equation it's used in, here you go

The work function is the Φ in the equation that relates the kinetic energy of the ejected electron to the energy supplied by a photon and the work function.

The work function is the Φ in the equation that relates the kinetic energy of the ejected electron to the energy supplied by a photon and the work function.

- Thu Oct 10, 2019 12:06 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation
- Replies:
**3** - Views:
**328**

### Re: Rydberg Equation

Rydberg Equation: 1/λ=R(1/n(1)^2−1/n(2)^2) You can change n(1) and n(2), which refer to different energy levels in the Hydrogen atom. For example, you can use n(1)= 1 and n(2)=2 to find the wavelength of light emitted when an electron drops from the n=2 to the n=1 energy levIel (or the wavelength o...

- Fri Oct 04, 2019 9:49 am
- Forum: Limiting Reactant Calculations
- Topic: Problem From Limiting Reactant Module
- Replies:
**2** - Views:
**41**

### Re: Problem From Limiting Reactant Module

Hi, to solve this problem, first the equation needs to be fully balanced. There's already a stoichiometric coefficient in front of AgNO3, however there also needs to be a 3 in front of AgCl. So, the resulting equation should be: C6H9Cl3 + 3AgNO3 ---> 3AgCl + C6H9(NO3)3 Then, find the molar masses o...

- Thu Oct 03, 2019 3:18 pm
- Forum: Limiting Reactant Calculations
- Topic: Problem From Limiting Reactant Module
- Replies:
**2** - Views:
**41**

### Problem From Limiting Reactant Module

Hey all, I was hoping for help on one of the problems from the module that I simply wasn't able to get even a remotely close answer for. Any explanation would be very helpful. The problem is as follows: 22. According to the following equation, 0.750 g of C 6 H 9 Cl 3 is mixed with 1.000 kg of AgNO 3...

- Tue Oct 01, 2019 12:40 am
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Accuracy vs Precision
- Replies:
**10** - Views:
**89**

### Re: Accuracy vs Precision

Jesse H 3 wrote:precision is consistent results while accuracy is how close to the true value we can get.

this response is succinct and how I'm going to think of it from now on. thanks

- Tue Oct 01, 2019 12:36 am
- Forum: SI Units, Unit Conversions
- Topic: Significant 0’s [ENDORSED]
- Replies:
**8** - Views:
**351**

### Re: Significant 0’s [ENDORSED]

if it helps, think about how it would be written in scientific notation. for example .085 would be 8.5*10 -2 (meaning the 0 after the decimal is not significant) while .850 would be written as 8.50*10 -1 (so the zero is significant :). for a number like 100 or 200 the zeros aren't considered signifc...

- Tue Oct 01, 2019 12:25 am
- Forum: Empirical & Molecular Formulas
- Topic: No need to use 100g for calculating molecular/empirical formulas
- Replies:
**1** - Views:
**57**

### No need to use 100g for calculating molecular/empirical formulas

If you're looking for a shortcut, or think that it seems strange that we usually take the mass percentage compositions and pretend there's 100g of substance, well here's a way you can just skip the step altogether. (Note that this is if you're given mass percentage compositions, and the molar mass f...

- Mon Sep 30, 2019 11:50 pm
- Forum: Significant Figures
- Topic: Decimals After Whole Numbers
- Replies:
**6** - Views:
**195**

### Re: Decimals After Whole Numbers

Yes. 100 only has 1 sig fig while 100. has 3 sig figs. The decimal part is an important factor if you are dealing with 0's. Important too, .001 has 1 sig fig, while .100 has 3 sig figs for example. .00100 would have 3. Thanks for the inclusion of the zeroes after the decimal but before any nonzero ...

- Mon Sep 30, 2019 11:45 pm
- Forum: SI Units, Unit Conversions
- Topic: mol, g.mol and g.mol-1
- Replies:
**12** - Views:
**121**

### Re: mol, g.mol and g.mol-1

g*mol

^{-1}is a weird notation, it can be more simply read as g/mol grams PER mole (since taking a negative exponent means multiplying by the reciprocal). I'm not 100% sure why this is the notation is used, maybe to fit everything in one line.