Search found 59 matches

by Mariah
Mon Jan 13, 2020 2:42 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: What is this?
Replies: 21
Views: 98

Re: What is this?

805097738 wrote:This principle tries to minimize the effect of change by shifting the direction of the reaction in order to maintain equilibrium


Just to clarify, it can shift either way right?
by Mariah
Mon Jan 13, 2020 2:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solid and Liquid
Replies: 5
Views: 19

Re: Solid and Liquid

Hannah Romeo 1J wrote:Solids and liquids are not included in the K expression as they do not change their concentrations in a reaction as they are pure substances. Essentially, their value is 1 resulting in the K expression only including aqueous solutions.


As well as gases!!
by Mariah
Mon Jan 13, 2020 2:41 pm
Forum: Ideal Gases
Topic: equilibrium constant purpose
Replies: 7
Views: 21

Re: equilibrium constant purpose

It helps us to know the ratio of products and reactants when a rx is at equilibrium.
by Mariah
Mon Jan 13, 2020 2:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw calcuation
Replies: 5
Views: 22

Re: Kw calcuation

Its basically omitted because it only changes slightly.
by Mariah
Mon Jan 13, 2020 2:39 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Practice Problems
Replies: 4
Views: 35

Re: Practice Problems

There is actually a Khan Academy section that has some video lessons and practice problems related to Le Chatlier's Principle https://www.khanacademy.org/science/chemistry/chemical-equilibrium/factors-that-affect-chemical-equilibrium/v/le-chatelier-s-principle This is actually a really good khan ac...
by Mariah
Mon Jan 13, 2020 2:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp and Kc
Replies: 4
Views: 14

Re: Kp and Kc

You use them when referring to what information is given or asked for. Yes, we use the ideal gas law to switch between the two if needed.
by Mariah
Sat Dec 07, 2019 2:19 pm
Forum: General Science Questions
Topic: Curve
Replies: 9
Views: 98

Re: Curve

He is not going to make it worth less, but he will curve the class at the end depending on how everyone does out of 500 points.
by Mariah
Sat Dec 07, 2019 2:17 pm
Forum: Properties of Electrons
Topic: Mass of an electron
Replies: 9
Views: 59

Re: Mass of an electron

Malia Shitabata 3H wrote:Do we have to memorize the mass of an electron since it's a constant or will it be given on the reference sheet?


Its on the reference sheet.
by Mariah
Sat Dec 07, 2019 2:16 pm
Forum: Lewis Acids & Bases
Topic: Water
Replies: 7
Views: 46

Re: Water

905174774 wrote:Is what considered a base or acid? Or does it just depends on what the problem is?


It is amphoteric which means it can act as both.
by Mariah
Sat Dec 07, 2019 2:15 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen bonds
Replies: 1
Views: 19

Re: Hydrogen bonds

An H-bond must be bonding to an NOF, but it would already be connected to an NOF within itself.
by Mariah
Sat Dec 07, 2019 2:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Disobeying the octect rule
Replies: 4
Views: 34

Re: Disobeying the octect rule

Yes, this is safe to say.
by Mariah
Sat Dec 07, 2019 2:12 pm
Forum: Bronsted Acids & Bases
Topic: Relative strength of acids
Replies: 1
Views: 17

Re: Relative strength of acids

You are supposed to compare the compound as is.
by Mariah
Sat Dec 07, 2019 1:34 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Number of bonding sites on a chelating ligand
Replies: 1
Views: 20

Re: Number of bonding sites on a chelating ligand

For the purpose of the chelating ligands, we are using you can see on Lavelles website that certain ligands have a set number of bonding sites. You have to memorize it.
by Mariah
Thu Dec 05, 2019 4:22 pm
Forum: Bronsted Acids & Bases
Topic: J.7
Replies: 8
Views: 70

Re: J.7

chari_maya 3B wrote:I don't understand part b... I know that N is more electronegative than Zn so Zn(OH) must be the bronsted base, but I don't understand why it is Zn(OH)2.


It has to be that because zinc has a +2 charge and OH has a -1 charge.
by Mariah
Thu Dec 05, 2019 3:52 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating Ligands and Coordination Numbers
Replies: 4
Views: 44

Chelating Ligands and Coordination Numbers

Would our coordination number be raised by just counting the chelating ligand, or how many times it is chelated to the metal?
by Mariah
Thu Dec 05, 2019 3:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Homework question 9C.7
Replies: 2
Views: 40

Re: Homework question 9C.7

Andrea_3F wrote:9C.7 Which of the following isomers of diaminobenzene can form chelating complexes? Explain your reasoning.

How do you know which isomers can form chelating complexes?


You can tell by remembering the main shapes of coordination compounds and which would fit without straining the bonds.
by Mariah
Sun Dec 01, 2019 3:47 pm
Forum: Biological Examples
Topic: Chemotherapy
Replies: 6
Views: 41

Re: Chemotherapy

Zoya Mulji 1F wrote:What are some examples of coordination compounds used as chemotherapy drugs?


I think we only need to know about cisplatin.
by Mariah
Sun Dec 01, 2019 3:45 pm
Forum: Sigma & Pi Bonds
Topic: Ionic bond --> sigma and pi bonds
Replies: 8
Views: 70

Re: Ionic bond --> sigma and pi bonds

Chloe Alviz 3F wrote:In the textbook, it says that all single covalent bonds are sigma bonds. If this is the case, how would we define the bond for an ionic compound such as NaCl?


Sigma and Pi bonds are only present in covalent bonds, as you said above.
by Mariah
Sun Dec 01, 2019 3:45 pm
Forum: Industrial Examples
Topic: What do we need to know?
Replies: 15
Views: 123

Re: What do we need to know?

What do we need to know about these coordination compounds??
by Mariah
Sun Dec 01, 2019 3:44 pm
Forum: Amphoteric Compounds
Topic: Identifying Them?
Replies: 12
Views: 57

Re: Identifying Them?

Isabel Day 1D wrote:You can identify an amphoteric compound by seeing if it would be able to both accept and donate hydrogen atoms.


So in this case, would water be amphoteric?
by Mariah
Sun Dec 01, 2019 3:42 pm
Forum: Trends in The Periodic Table
Topic: Nitrogen
Replies: 3
Views: 44

Re: Nitrogen

I believe it has something to do with the three unpaired electrons in the p orbital, and the fact that energy would be needed to add an electron to nitrogen. In the contrary, energy is released when added to oxygen.
by Mariah
Sun Nov 24, 2019 1:26 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Charges
Replies: 4
Views: 36

Re: Charges

005388369 wrote:Is memorizing the only way to know the ionic charges in the periodic table?


I know that if you look uo ionic charge trends it shows it on the periodic table, this was the easiest way for me to do it.
by Mariah
Sun Nov 24, 2019 1:24 pm
Forum: Dipole Moments
Topic: Dipole Induced- Dipole Induced
Replies: 13
Views: 82

Re: Dipole Induced- Dipole Induced

This type of inter-molecular force is the same thing as a Van der Wall force and can occur with any molecule and is the weakest form of inter-molecular force. Well an example for this is basically any molecule because even if it doesn't happen as often, there will be a point in time where two eleme...
by Mariah
Sun Nov 24, 2019 1:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw
Replies: 23
Views: 123

Re: Seesaw

According to the solution manual of E15, a seesaw would have an approximate angle of 90 and 120 degrees. Wouldn't the angles be less than 90 and 120 due to the lone pair causing a smaller angle than the typical angles of an electron arrangement of a trigonal bipyramidal? It is less than 120 or 90 b...
by Mariah
Sun Nov 24, 2019 1:21 pm
Forum: Hybridization
Topic: Strength of sigma and pi bonds
Replies: 8
Views: 32

Re: Strength of sigma and pi bonds

Omar Selim 3H wrote:sigma bonds are harder to break than pi bonds because the former are a result of end-to-end bonding while the latter consist of side-to-side bonds


So then why are double bonds stronger than single bonds? If they contain a sigma and pi versus just one sigma?
by Mariah
Sun Nov 24, 2019 1:20 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation states
Replies: 6
Views: 35

Re: Oxidation states

The oxidation numbers are determined based off the charge of the ion itself. For example if the compound was C2H6, the oxidation number of the H would be +1 and the C is -3 so when you add the total together it would be (1x6)+ (-3x2) which would make the oxidation number of the whole molecule 0. So...
by Mariah
Tue Nov 12, 2019 12:30 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization of Nitrogen vs Oxygen
Replies: 11
Views: 59

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: 59

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: 39

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: 20

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: 61

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: 20

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: 29

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: 7
Views: 69

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: 109

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: 18
Views: 71

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: 33

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: 67

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: 62

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: 15

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: 23

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: 15

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: 114

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: 66

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: 45

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: 52

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: 75

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: 35

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: 67

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: 33

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: 128

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: 86

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: 128

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: 50

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: 154

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: 116
Views: 11121

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: 116
Views: 11121

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: 38

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: 52

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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