Search found 33 matches

by Mariah
Tue Nov 12, 2019 12:30 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization of Nitrogen vs Oxygen
Replies: 11
Views: 37

Re: Ionization of Nitrogen vs Oxygen

Is this the only case that doesn't follow the ionization trend?
by Mariah
Tue Nov 12, 2019 12:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Week 7 Homework
Replies: 7
Views: 34

Re: Week 7 Homework

I was a bit confused about this too because of the midterm but I am assuming still Chemical Bonds.
by Mariah
Tue Nov 12, 2019 12:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: central atoms
Replies: 7
Views: 23

Re: central atoms

Tiffany Dong_4e wrote:The central atom is typically determined by whichever atom has the lowest electronegativity. Aside from this, the atom which is alone or has the lowest quantity is usually in the center.


This is probably the best rule to follow! Try not to over complicate it because it may confuse you more.
by Mariah
Tue Nov 12, 2019 12:26 pm
Forum: Dipole Moments
Topic: London forces
Replies: 4
Views: 12

Re: London forces

They occur with all molecules because all molecules have electrons floating around the cloud that sometimes create momentary charges. We learned about it in LS7A and they showed us a video about Geckos. I think if you look up Van der Waals Gecko it might help you understand the concept.
by Mariah
Tue Nov 12, 2019 12:13 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: HW 2D.3
Replies: 5
Views: 34

Re: HW 2D.3

BaBr2 is more ionic compare to BeBr2 and BBr3 because the electronegativity difference between Ba-Br is the greatest compares to electronegativity difference between Be-Br and B-Br. Electronegativity increases across the period and decreases down the group. Therefore the electronegativity differenc...
by Mariah
Fri Nov 08, 2019 5:10 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: DNA
Replies: 3
Views: 19

Re: DNA

You can also see how there is only a double bond between A and T which helps to remember there is only 2 hydrogen bonds, which makes it weaker than G and C pairs that have a triple bond.
by Mariah
Fri Nov 08, 2019 5:09 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Shortcut
Replies: 3
Views: 20

Re: Formal Charge Shortcut

Count the bonds around the atom as 1 electron and then count each lone pair as 2 electrons (count each dot you drew individually) and you want this to add up to the number of valence of electrons of the actual element. However if this is on a test then you should show the actual calculation. My TA ...
by Mariah
Fri Nov 08, 2019 5:08 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Electron configuration
Replies: 5
Views: 37

Re: Electron configuration

Anisha Chandra 4H wrote:Yes, the 4s orbital is lower energy than 3d, but once 4s is filled, it becomes higher energy than 3d, which is why electrons will be removed from 4s before 3d during ionization.


So to clarify, if we need to remove electrons we would go to 4s before 3d, because this confused me.
by Mariah
Fri Nov 08, 2019 5:07 pm
Forum: Electronegativity
Topic: Ionic or covalent?
Replies: 17
Views: 97

Re: Ionic or covalent?

Leila_4E wrote:Will we have to know the actual values of electronegativity to determine the minute differences? I assume probably not..


I was told that we do not, but it might help when trying to figure it out. I think it just depends on your understanding.
by Mariah
Fri Nov 08, 2019 5:05 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 17
Views: 44

Re: Drawing Lewis Structures

I think the only time you have to make sure the formal charges are zero is when it asks to draw the most stable version.
by Mariah
Tue Oct 29, 2019 1:24 pm
Forum: Trends in The Periodic Table
Topic: electronegativity table
Replies: 5
Views: 27

Re: electronegativity table

DarrenKim_3G wrote:I think we would just have to know that electronegativity increases bottom to top in groups and left to right across periods


Electronegativity becomes relevant in drawing lewis structures correct? Or is that a different trend?
by Mariah
Tue Oct 29, 2019 1:21 pm
Forum: Bond Lengths & Energies
Topic: bond lengths
Replies: 10
Views: 40

Re: bond lengths

Alexa Hernandez 3k wrote:The more Bonds means a stronger pull so consequently you also get a smaller length because of the increased attraction.


So the smaller the bond, the stronger it is?
by Mariah
Tue Oct 29, 2019 1:18 pm
Forum: Ionic & Covalent Bonds
Topic: Octet Rule
Replies: 8
Views: 40

Octet Rule

How do we know which elements have expanded octets? Do these need to be memorized?
by Mariah
Tue Oct 29, 2019 1:16 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron Configurations
Replies: 3
Views: 11

Re: Electron Configurations

Jamie Lee 1D wrote:Any electron configuration can be written in shorthand, so you can write ground-state or excited-state configurations using shorthand.


Thank you! This helps, what are the differences between ground-state and excited-state configurations?
by Mariah
Tue Oct 29, 2019 1:12 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2A.23
Replies: 2
Views: 15

HW 2A.23

This question confused me as it is asking for the chemical formula for Aluminum Hydride. Don't Aluminum and Hydrogen both have positive charges? Are they allowed to bond with each other?
by Mariah
Tue Oct 29, 2019 1:02 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron Configurations
Replies: 3
Views: 11

Electron Configurations

Are noble gas electron configurations, or shorthand, the same as ground-state configurations? If a homework problem asks for the ground-state configuration of an element, is a noble gas shorthand allowed to be used?
by Mariah
Tue Oct 22, 2019 12:48 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Atomic Radius
Replies: 18
Views: 79

Re: Atomic Radius

The atomic radius is half the distance between the nuclei of two identical atoms bonded together. For the purpose of this class I don't think we would be calculating the exact value of the radius. During the lecture, a picture was shown that said 2r from both nuclei of atoms bonded together. Do you...
by Mariah
Tue Oct 22, 2019 12:42 pm
Forum: Trends in The Periodic Table
Topic: Ionic radii
Replies: 11
Views: 57

Re: Ionic radii

I have a question regarding whether it's a cation or anion. Does that affect the ionic radius of the element? In my notes, I wrote "cations are smaller than their parent atoms and anions are larger" I wrote the same, I think they do have an effect on the radius of an element, but I don't ...
by Mariah
Tue Oct 22, 2019 12:39 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1E. 1
Replies: 4
Views: 35

Re: 1E. 1

All of these also increase for a hydrogen atom as well. I think the important part of the question is understanding why these increase in a hydrogen atom versus a lithium atom. For a, b, and c, (all properties that apply to single-electron systems), the reason for the increase is the same between h...
by Mariah
Tue Oct 22, 2019 12:36 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D.1
Replies: 5
Views: 42

Re: 1D.1

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?
by Mariah
Tue Oct 22, 2019 12:31 pm
Forum: DeBroglie Equation
Topic: HW 1.41
Replies: 6
Views: 67

Re: HW 1.41

So, can we reorganize this equation to find velocity? Would V=(h/wavelength*m) be correct?
by Mariah
Tue Oct 22, 2019 12:19 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Problem 1a.11
Replies: 3
Views: 23

Re: Problem 1a.11

I am also confused about this, are they grouped by which lower energy level they are moving towards?
by Mariah
Wed Oct 16, 2019 4:59 pm
Forum: Quantum Numbers and The H-Atom
Topic: X Y and Z
Replies: 7
Views: 48

Re: X Y and Z

Qiu Ya Wu 4F wrote:In his lecture today, Lavelle emphasized that the plane the electron is found in is arbitrary and different textbooks associate different l values with different x,y, and z planes.


So, because he said this we can assign the x,y,z variables to the values we have correct? That confused me as well.
by Mariah
Wed Oct 16, 2019 4:56 pm
Forum: Photoelectric Effect
Topic: Particle vs. Wave Model
Replies: 5
Views: 27

Re: Particle vs. Wave Model

I just watched a video that described it as wave-packets, which have both the properties of waves and particles. That concept helped me to understand the photoelectric effect, I hope it helps you too.
by Mariah
Wed Oct 16, 2019 4:53 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula Help [ENDORSED]
Replies: 7
Views: 87

Re: Empirical Formula Help [ENDORSED]

Thank you! This helps a lot. I did not know we could round if it was just a couple hundreths off.
by Mariah
Tue Oct 15, 2019 1:23 pm
Forum: Einstein Equation
Topic: 1B.9
Replies: 5
Views: 62

Re: 1B.9

Can anyone explain how the units should turn out? Or how they work throughout the problem because I am having trouble with that.
by Mariah
Tue Oct 08, 2019 11:36 am
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula Help [ENDORSED]
Replies: 7
Views: 87

Re: Empirical Formula Help [ENDORSED]

What if you cannot multiply to get a whole number? If I have 2.66 for example, could I just round to 3?
by Mariah
Thu Oct 03, 2019 8:45 pm
Forum: Significant Figures
Topic: Significant Figures
Replies: 6
Views: 34

Re: Significant Figures

Try to avoid rounding to how many significant figures you need until the very end or your final answer. If you do it throughout the problem, it makes your answer less accurate.
by Mariah
Thu Oct 03, 2019 8:44 pm
Forum: Balancing Chemical Reactions
Topic: Understanding how to get whole #s [ENDORSED]
Replies: 18
Views: 128

Re: Understanding how to get whole #s [ENDORSED]

If you are doing the empirical formula, I think that is when you have to worry about making things a whole number. Just remember you can manipulate numbers by multiplying, and dividing by the smallest if needed. Also whatever you do to one number, make sure to do to the others as well. If you fail t...
by Mariah
Thu Oct 03, 2019 8:40 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 115
Views: 10295

Re: All students read this sig fig post [ENDORSED]

When taking values from the periodic table (ex. for calculating molar mass), how many significant figures do you round to? Try to not round answers until the very last step. I usually use the entire given value from the periodic table then round to the smallest number of significant figures used in...
by Mariah
Thu Oct 03, 2019 8:39 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 115
Views: 10295

Re: All students read this sig fig post [ENDORSED]

Jordanmjones13 wrote:Do you know if the problems will specifically tell us how many significant figures to use?


I don't think it will tell us, you will be left to figure it out by referring to the information given. There is a lot of good crash courses on how to count sig figs online. I hope this helps!
by Mariah
Thu Oct 03, 2019 8:37 pm
Forum: Properties of Light
Topic: CHEM 1A
Replies: 2
Views: 34

Re: CHEM 1A

I think that although it's light, it's still being emitted in a way so thats why the energy changes. As they travel from energy level to energy level, they shed off energy in the form of light.
by Mariah
Thu Oct 03, 2019 8:33 pm
Forum: SI Units, Unit Conversions
Topic: Clarification for SI Units
Replies: 4
Views: 45

Re: Clarification for SI Units

You definitely wrote all of these correct! Although it might not be REQUIRED to have them memorized, I would advise it. They will come up in topics other than chem as well, and its good fundamental knowledge for STEM classes and such.

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