Search found 107 matches

by AArmellini_1I
Wed Mar 11, 2020 9:37 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Observed and experimental rate
Replies: 1
Views: 35

Re: Observed and experimental rate

Observed rate is the rate that an experiment would find, the experimental rate is the rate we would expect (such as the rate of the slow step). These rates always equal one another but it may not look like they do. When this happens you have to look at the equilibrium constant of the previous faster...
by AArmellini_1I
Wed Mar 11, 2020 9:34 am
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 5
Views: 119

Re: Final

He hasn't specified but from the sounds of it, it may be flexible.
by AArmellini_1I
Tue Mar 10, 2020 5:35 pm
Forum: Administrative Questions and Class Announcements
Topic: ENDGAME Review Session
Replies: 71
Views: 2757

Re: ENDGAME Review Session

Thank you so much for all your help! I know it may be a lot to ask but I really would appreciate it if you could livestream or record a review session. They help me so much for the exam
by AArmellini_1I
Tue Mar 10, 2020 5:30 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Angular dependence
Replies: 2
Views: 24

Re: Angular dependence

Do you mean the lower the activation energy the greater k and the higher the activation energy the smaller k is?
by AArmellini_1I
Tue Mar 10, 2020 5:29 pm
Forum: Administrative Questions and Class Announcements
Topic: Situation for Lecture, Discussion, and Final
Replies: 3
Views: 131

Re: Situation for Lecture, Discussion, and Final

Also, does anyone know if review sessions will still be held?
by AArmellini_1I
Wed Mar 04, 2020 9:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: platinum
Replies: 2
Views: 48

Re: platinum

It's because the solid on the anode side is iodine which is not a metal. You need a solid metal to conduct electricity and thus allow for the movement of electrons
by AArmellini_1I
Wed Mar 04, 2020 9:02 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number
Replies: 5
Views: 59

Re: Oxidation number

This goes back to Chem14A. You can find an elements oxidation level by looking at the periodic table. For examples, group 1 elements like to lose one electron so they are +1, and halogens like to gain one electron so they are typically -1. But when you are dealing with a compound with multiple eleme...
by AArmellini_1I
Wed Mar 04, 2020 8:58 pm
Forum: Balancing Redox Reactions
Topic: confusing homework question
Replies: 4
Views: 83

Re: confusing homework question

It's because the whole point of your solid electrode is that it can conduct electricity (movement of electrons) which only metals can effectively do. So will you do have a solid, iodine cannot be the electrode because it is not a metal
by AArmellini_1I
Wed Mar 04, 2020 8:57 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating cell potential of an electrode
Replies: 2
Views: 55

Re: Calculating cell potential of an electrode

I would always check what is spontaneous because that will help you to confirm the cathode and anode
by AArmellini_1I
Wed Mar 04, 2020 8:55 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell diagrams
Replies: 1
Views: 27

Re: cell diagrams

If it is part of the reaction yes, because a compound can be both oxidizing and reducing in a concentration cell
by AArmellini_1I
Thu Feb 27, 2020 9:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 3
Views: 40

Re: Cell Diagrams

You include H+ ions if they don't cancel out in the final balanced redox reaction. I don't see why it would not be the same for water as well
by AArmellini_1I
Wed Feb 26, 2020 6:09 pm
Forum: Balancing Redox Reactions
Topic: balancing in acidic solutions
Replies: 4
Views: 72

Re: balancing in acidic solutions

Use H+ for acidic solutions and OH- for basic :)
by AArmellini_1I
Wed Feb 26, 2020 6:08 pm
Forum: Balancing Redox Reactions
Topic: common oxidation numbers
Replies: 3
Views: 43

Re: common oxidation numbers

Also consider electronegativity when dealing with multiple group 5, 6 ,7 elements such as oxygen and sulfur. While both prefer gaining two electrons, oxygen is more electronegative so if the two were to react S would likely be +6 rather than -2
by AArmellini_1I
Wed Feb 26, 2020 6:06 pm
Forum: Balancing Redox Reactions
Topic: common oxidation numbers
Replies: 3
Views: 43

Re: common oxidation numbers

You can reference the periodic table and see what elements have however many electrons and whether they would prefer to gain or lose a specific number of electrons to fulfill the octet rule.
by AArmellini_1I
Wed Feb 26, 2020 6:05 pm
Forum: Balancing Redox Reactions
Topic: 6L.3 d)
Replies: 1
Views: 55

Re: 6L.3 d)

I believe it because you know the anode is an oxidation. And since you only have O2 and H+ for the anode the only reasonable reaction you can make were oxidation occurs would be having 2H2O --> 4H+ + 2OH- + 4e-. And same for reduction in the cathode. Since you only have OH- and O2 the only reasonabl...
by AArmellini_1I
Wed Feb 26, 2020 10:59 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: log or ln
Replies: 6
Views: 59

Re: log or ln

You want to use log when dealing with pH and [H+] [OH-] concentrations
by AArmellini_1I
Sat Feb 22, 2020 6:14 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8039
Views: 1411242

Re: Post All Chemistry Jokes Here

What was Avogadro's favorite sport?
Golf, because he always got a mole-in-one!
by AArmellini_1I
Sat Feb 22, 2020 6:00 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Textbook progress
Replies: 3
Views: 35

Re: Textbook progress

I had the same question, but I believe we may have completed it, or at the very least through 6N (I think we covered 6O too though)
by AArmellini_1I
Sat Feb 22, 2020 5:58 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell diagrams
Replies: 2
Views: 50

Re: Cell diagrams

I think you have to assume that both half reactions are interacting with water because water is the only solvent we use in redox reactions in regards to this class
by AArmellini_1I
Sat Feb 22, 2020 5:54 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Using an inert electrode
Replies: 2
Views: 16

Re: Using an inert electrode

I was a bit curious about that question too. The best reason I can come up with is that the solid included in the reaction is a product, not a reactant. Therefore it can't serve as the electrode initially because it hasn't been produced yet, so you have to have an inert electrode to initiate the rea...
by AArmellini_1I
Sat Feb 22, 2020 5:52 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.7
Replies: 1
Views: 38

Re: 6L.7

Ag(s) doesn't have a positive charge because it is not interacting with another element and therefore cannot be gaining or losing an electron
by AArmellini_1I
Tue Feb 11, 2020 5:09 pm
Forum: Calculating Work of Expansion
Topic: delta U for an ideal gas expansion
Replies: 3
Views: 44

Re: delta U for an ideal gas expansion

Thanks, if we were told that a gas expansion is isothermal, do you think that we should assume it's an ideal gas if not specified (so that we can use the fact that delta U=0)? Yeah I believe so! But I don't think whether or not it is an ideal gas influences delta U = 0. I'm pretty sure that stateme...
by AArmellini_1I
Tue Feb 11, 2020 5:06 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Change in enthalpy (4C.3)
Replies: 1
Views: 42

Re: Change in enthalpy (4C.3)

For constant pressure q = delta H not delta S. So you would use delta S = q/T or delta H / T (you may also be able to use delta S = -n R ln (V2/V1)?
For constant volume you also still use q/T but couldn't use S = -n R ln (V2/V1)
If the system is isothermal use delta S = n C ln (T2/T1)
by AArmellini_1I
Tue Feb 11, 2020 5:02 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: S = q/T
Replies: 5
Views: 62

Re: S = q/T

Yep! If you have changing temperature then you use delta S = n C ln (T2/T1)
by AArmellini_1I
Tue Feb 11, 2020 5:00 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: reversible expansion vs. irreversible free expansion
Replies: 2
Views: 50

Re: reversible expansion vs. irreversible free expansion

The only real difference is how the work was done. In an irreversible reaction the expansion occurs instantaneously, where as in a reversible reaction the expansion occurs over infinitely small expansions.
by AArmellini_1I
Tue Feb 11, 2020 4:54 pm
Forum: Calculating Work of Expansion
Topic: reversible vs irreversible expansions
Replies: 2
Views: 37

Re: reversible vs irreversible expansions

Then it's based on your conditions regarding the system. Is there constant pressure? How about constant temperature? etc.
by AArmellini_1I
Tue Feb 11, 2020 4:51 pm
Forum: Calculating Work of Expansion
Topic: delta U for an ideal gas expansion
Replies: 3
Views: 44

Re: delta U for an ideal gas expansion

Because isothermal means energy/heat and matter cannot leave or enter the system, therefore the internal energy of the system (delta U) is constant
by AArmellini_1I
Wed Feb 05, 2020 7:36 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.7
Replies: 2
Views: 28

Re: 4F.7

I don't have my homework on me right now but on thing I messed up on was using the wrong R, check your units and make sure everything cancels and you get the correct units. Different R's have different units
by AArmellini_1I
Wed Feb 05, 2020 7:29 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reversible and Irreversible
Replies: 3
Views: 51

Re: Reversible and Irreversible

Because for infinitesimally small expansion, work must be done and equilibrium must be regained. This repeats over and over and this creates a decreasing curve where as irreversible expansion occurs immediately so work occurs instantly only once and equilibrium is only regained once (this creates a ...
by AArmellini_1I
Wed Feb 05, 2020 7:24 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy as three steps
Replies: 2
Views: 51

Re: Entropy as three steps

You have to cool it because in order to vaporize you must be at 100C. So first you have to increase the temperature to 100, then vaporize, then reduce the temp back down to 85degrees in order to satisfy the question
by AArmellini_1I
Wed Feb 05, 2020 7:22 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 7
Views: 100

Re: Midterm

Not that I am aware of but usually they email the class when they do
by AArmellini_1I
Mon Feb 03, 2020 5:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 177
Views: 13506

Re: Advice from a Medical Student - Part II [ENDORSED]

Thank you so much for posting a part 2! I was so excited to see it. I was wondering how you found opportunities (work, internships, volunteering, really any experience). As you probably are well aware pre-med programs at UCLA are tough to get into especially as a first year. Do you have any tips or ...
by AArmellini_1I
Thu Jan 30, 2020 9:41 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Enthalpy at Constant Pressure
Replies: 2
Views: 29

Re: Enthalpy at Constant Pressure

I believe it just means that its a closed system (like a piston) so while volume may change the pressure will never change because the system can expand and contract
by AArmellini_1I
Thu Jan 30, 2020 9:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4E.7
Replies: 1
Views: 31

Re: 4E.7

Thats because you only need to break:
1 O-H (463kJ/mol) and 1 C=C (612kJ/mol)
And you form:
1 C-H -1(412) 1 C-O -1(360kJ/mol) and 1 C-C -1(348kJ/mol)
Add that all up and you get -45kJ/mol
by AArmellini_1I
Tue Jan 28, 2020 10:35 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpies
Replies: 4
Views: 50

Re: Enthalpies

Standard reaction enthalpy is the enthalpy of the P and R at their most stable point. Standard enthalpy of formation is the summation of all the R and P standard reaction enthalpy [I think but I may have messed this up]
by AArmellini_1I
Tue Jan 28, 2020 10:27 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4E.5, 4E.7
Replies: 4
Views: 94

Re: 4E.5, 4E.7

4E.5
3(837)kJ/mol - 6(518)kJ/mol = -597 kJ/mol
4E.7
a)
1(944)kJ/mol + 3(158)kJ/mol - 6(270)kJ/mol = -202kJ/mol
b)
1(463)kJ/mol + 1(612)kJ/mol - 1(412)kJ/mol - 1(360)kJ/mol - 1(348)kJ/mol = -45kJ/mol
c)
1(412)kJ/mol + 1(242)kJ/mol - 1(338)kJ/mol - 1(431)kJ/mol = -115 kJ/mol

Hope this helps!
by AArmellini_1I
Mon Jan 27, 2020 10:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework sections
Replies: 7
Views: 80

Re: Homework sections

Actually I think its 4E and maybe 4D, I'm pretty sure Lavelle said we are going backwards
by AArmellini_1I
Wed Jan 22, 2020 3:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: state property
Replies: 5
Views: 29

Re: state property

Because the total enthalpy you end with is not dependent on the process you took to get to that point (like if I boil a pot of water and tell you it initially was 80 degrees and now its 150 degrees. You would tell me the temperature increased by 70 degrees, you wouldn't need to know how long I boile...
by AArmellini_1I
Wed Jan 22, 2020 2:57 pm
Forum: Phase Changes & Related Calculations
Topic: phase transitions
Replies: 3
Views: 44

Re: phase transitions

Because the more energy provided the more the substance starts to become the next phase, but this energy must go to maintaining that phase so increasing heat won't increase temperature until the substance has completely achieved the next phase
by AArmellini_1I
Wed Jan 22, 2020 2:49 pm
Forum: Phase Changes & Related Calculations
Topic: Heat curve for water
Replies: 2
Views: 34

Re: Heat curve for water

Ok so this might be hard to explain without the picture but basically while converting a liquid to a gas, by increasing the heat you don't actually change the temperature of the substance itself because all that extra heat is being used to hold the newly developing phase. Temperature of a substance ...
by AArmellini_1I
Wed Jan 22, 2020 2:43 pm
Forum: Phase Changes & Related Calculations
Topic: - and + H values
Replies: 5
Views: 56

Re: - and + H values

Because delta H = enthalpy of final(or product) - enthalpy of initial(or reactant). Exothermic reactions release energy, therefore the enthalpy of the product is less than the enthalpy of the reactants. A small number - a bigger number results in a negative value for delta H. And vice versa for endo...
by AArmellini_1I
Wed Jan 22, 2020 2:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: approximation
Replies: 5
Views: 47

Re: approximation

Basically if K is less than 10^3, meaning that the acid/base barely disassociates, then we can assume that the dissociation affects the initial condition of your acid/base so little that it's insignificant. This means that when calculating your x, or the change in concentration, instead of have your...
by AArmellini_1I
Thu Jan 16, 2020 11:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Tips for Test
Replies: 23
Views: 267

Re: Tips for Test

I really like Lydon's (spelt his name wrong) workshop on Monday's in Covel. He gives you a worksheet and eventually the answers and it usually covers most (if not all) the material on the test
by AArmellini_1I
Thu Jan 16, 2020 11:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Checking Answers
Replies: 1
Views: 19

Re: Checking Answers

If your dealing with acids and bases you can always plug your x back into your equation or convert your answer back into pKa, pH, etc to see if your answer makes sense
by AArmellini_1I
Thu Jan 16, 2020 11:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Changes in K and Q
Replies: 2
Views: 23

Re: Changes in K and Q

K changes in terms of temperature but not by increasing/decreasing the concentration of your products or reactants. Q just tells you what direction you reaction is moving (forward/reverse) as it approaches equilibrium or K.
by AArmellini_1I
Thu Jan 16, 2020 11:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook clarification: weak acids and bases
Replies: 3
Views: 41

Re: Textbook clarification: weak acids and bases

So because it is a very weak acid/base it only dissociates by a small concentration. Therefore, since your KA or B is [products] / [reactants] and only a small concentration will dissociate into the product, Ka or B is a very small number divided by a much bigger number which = a very small number :...
by AArmellini_1I
Tue Jan 14, 2020 5:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G 9 HW C VS. D AND E
Replies: 2
Views: 47

Re: 5G 9 HW C VS. D AND E

basically the only thing the remains unchanged in the equilibrium constant, and since d is the equilibrium constant and e is the reciprocal, they won't change. And while c does have products/reactants, it lacks the correct exponents so a change in concentration of a reactant or product would result ...
by AArmellini_1I
Sun Jan 12, 2020 8:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp vs Kc usage
Replies: 5
Views: 50

Re: Kp vs Kc usage

If it's talking about gases used Kp for partial pressure. If it's talking about aqueous solutions use Kc for concentration.
by AArmellini_1I
Sun Jan 12, 2020 8:36 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient
Replies: 11
Views: 81

Re: Reaction Quotient

It really doesn't have a ton of application in real-life scenarios so you really just need to understand it as it applies to the homework
by AArmellini_1I
Sun Jan 12, 2020 8:34 pm
Forum: Ideal Gases
Topic: The Laws
Replies: 7
Views: 71

Re: The Laws

So far Lavelle has only really touched on PV=nRT
by AArmellini_1I
Fri Jan 10, 2020 10:05 am
Forum: Administrative Questions and Class Announcements
Topic: Discussion 1J with TA Kevin?
Replies: 2
Views: 56

Re: Discussion 1J with TA Kevin?

I would check your assigned TA again, there may have been a change the morning of.
by AArmellini_1I
Wed Jan 08, 2020 4:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: changing K
Replies: 4
Views: 58

Re: changing K

I believe so because both variable uses [products]/[reactants] so I would assume the trends are the same
by AArmellini_1I
Thu Dec 05, 2019 12:29 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation use
Replies: 2
Views: 122

Re: Rydberg Equation use

If you get the right answer no but if you don't get the right answer you may not get as many partial credit points that you would if you did it Lavelle's way
by AArmellini_1I
Thu Dec 05, 2019 12:27 pm
Forum: Lewis Acids & Bases
Topic: 6.13
Replies: 1
Views: 36

Re: 6.13

I believe it is because it reacts with water?
by AArmellini_1I
Thu Dec 05, 2019 12:25 pm
Forum: Naming
Topic: Homework week 9
Replies: 1
Views: 35

Re: Homework week 9

I think I'd still with 6A and 6B to be safe and reserve 6C and 6D (maybe a little of 6B) for HW 10
by AArmellini_1I
Thu Dec 05, 2019 12:23 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Listing quantum numbers
Replies: 3
Views: 119

Re: Listing quantum numbers

I doubt so but if you know the book lists from - to + it wouldn't hurt to mimic it! Also it may confuse you when looking at what planes (x,y,z) your orbital is in but I don't think he really expects us to know that anyways
by AArmellini_1I
Thu Dec 05, 2019 12:21 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strength of Acids
Replies: 2
Views: 35

Re: Strength of Acids

For Binary acids: Across a period: more polar the HA bond the stronger the acid (weak bonds) Down a group: the weaker the HA bond the stronger the acid (so greater atomic diameter means a weak bond which means a stronger acid) For OxoAcids: The more O bonded to the central atom the stronger the acid...
by AArmellini_1I
Thu Dec 05, 2019 12:18 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Strength of bases
Replies: 1
Views: 90

Re: Strength of bases

It's all about how strongly a base will bond with a H+ so I recommend looking at what characteristics (such as EN and size) will affect it
by AArmellini_1I
Thu Dec 05, 2019 12:17 pm
Forum: Naming
Topic: amine or ammine
Replies: 2
Views: 42

Re: amine or ammine

And while they are different you won't (at least according to my TA) won't be docked an entire point for it
by AArmellini_1I
Sun Dec 01, 2019 10:43 pm
Forum: General Science Questions
Topic: Friday Lecture Week 10
Replies: 3
Views: 80

Re: Friday Lecture Week 10

Lavelle said in an email that we finish the syllabus Wednesday and start lecture that same day. So I'd assume Friday is also review :)
by AArmellini_1I
Sun Dec 01, 2019 10:42 pm
Forum: General Science Questions
Topic: Review in General
Replies: 4
Views: 117

Re: Review in General

I first use the outlines Lavelle provides us. Then I do practice problems and for things I forgot I create a quizlet. Then it's just more practice problems in the areas I struggle in
by AArmellini_1I
Sun Dec 01, 2019 10:41 pm
Forum: Hybridization
Topic: 2F.7
Replies: 2
Views: 44

Re: 2F.7

What I do first is draw the lewis structures. The number of electron dense regions corresponds with the hybridization orbital. For hybridization orbitals it go s, p1, p2, p3, d1, d2, d3, d4, d5 and so on (I believe)
by AArmellini_1I
Sun Dec 01, 2019 10:39 pm
Forum: General Science Questions
Topic: test taking nervousness
Replies: 19
Views: 314

Re: test taking nervousness

I have the same problem especially in this class. What I'm trying to do is not hyping up the test. Just view as it as an opportunity to prove your knowledge where you will earn as many points as possible as opposed to thinking about the points you may lose.
by AArmellini_1I
Sun Dec 01, 2019 10:06 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelating Ligands
Replies: 2
Views: 47

Re: Chelating Ligands

I believe by polydenate it means the ligand can form three of more chelated rings
by AArmellini_1I
Mon Nov 25, 2019 6:26 pm
Forum: Naming
Topic: Naming in Fundamentals J (acids and bases)
Replies: 2
Views: 37

Naming in Fundamentals J (acids and bases)

So I know Lavelle has discussed naming in terms of ligands but do we need to know the names for acids and bases? I only ask because in fundamentals J questions 7 and 9 the questions gives us compounds such as phosphoric acid and phosphate and we are asked to write the balanced chemical equations. Do...
by AArmellini_1I
Sun Nov 24, 2019 2:09 pm
Forum: Sigma & Pi Bonds
Topic: Orbital overlap
Replies: 4
Views: 65

Re: Orbital overlap

Ramneet Sandhu 3D wrote:A head-on overlap is formed by sigma bonds. Pi bonds are able to form side-to-side overlaps.

Which is why sigma bonds are stronger than pie bonds
by AArmellini_1I
Fri Nov 22, 2019 12:27 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 58
Views: 2147

Re: Study Tips

Flash Cards (especially with things that require memorization such as molecular shape) and I like making outlines of sections so I know what I need to know and can test myself to find out what I need to focus on (I pull a lot from Lavelle's outlines and my own notes)
by AArmellini_1I
Fri Nov 22, 2019 12:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Removing Non-Axis Atoms First
Replies: 4
Views: 74

Re: Removing Non-Axis Atoms First

It helps to picture the molecule and look at how many other angles a lone pair will affect in each region
by AArmellini_1I
Wed Nov 20, 2019 12:02 pm
Forum: Sigma & Pi Bonds
Topic: Why are sigma bonds stronger than pi bonds?
Replies: 6
Views: 92

Re: Why are sigma bonds stronger than pi bonds?

Because in a sigma bond the orbitals can overlap to a greater extent where as with pie bonds they are overlapping indirectly which means they can't overlap as much as sigma bond. The more they over lap, the stronger the pull
by AArmellini_1I
Tue Nov 19, 2019 6:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Memorization of Molecular Shapes
Replies: 1
Views: 38

Re: Memorization of Molecular Shapes

This isn't quite what you are asking for but I'm memorizing them by imaging the electron density shape then removing atoms and replace them with lone pairs. Then you can picture what the molecule looks like and make it easier to identify its shape. For shapes not consisting of lone pairs, I'm memori...
by AArmellini_1I
Fri Nov 15, 2019 5:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Formula Exceptions
Replies: 6
Views: 112

Re: VSEPR Formula Exceptions

I don't believe Lavelle has mentioned any so in terms of his class, I don't think you have to worry
by AArmellini_1I
Fri Nov 15, 2019 5:04 pm
Forum: Dipole Moments
Topic: Xenon
Replies: 4
Views: 77

Re: Xenon

I think he mentioned something about how since xenon has a low electronegativity, its electrons are more easily distorted by atoms with stronger electronegativity, like fluorine. Exactly! But he was careful to add that this cannot occur with some noble gases, specifically He and Ne, and only at ext...
by AArmellini_1I
Fri Nov 15, 2019 5:02 pm
Forum: Hybridization
Topic: 2F.13
Replies: 2
Views: 58

Re: 2F.13

If you would please give us the actual question. Then I think more people would be able to help! :)
by AArmellini_1I
Fri Nov 15, 2019 5:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape v Electron Geometry
Replies: 4
Views: 61

Re: Molecular Shape v Electron Geometry

It basically considering how the number of atoms bonded to the central atom will affect it's shape and how the number of electron dense regions (so bonded atom AND lone pairs) affect the bond angles of the initial shape. These two factors ultimately determine the shape of the molecule
by AArmellini_1I
Fri Nov 15, 2019 4:58 pm
Forum: Ionic & Covalent Bonds
Topic: Types of Covalent Bonds
Replies: 4
Views: 51

Re: Types of Covalent Bonds

Polar bonds are stronger than non-polar bonds due to their dipole movements. As for coordinate covalent compounds I am not sure
by AArmellini_1I
Fri Nov 08, 2019 10:58 am
Forum: Administrative Questions and Class Announcements
Topic: Midterm --> Final Concepts
Replies: 3
Views: 56

Re: Midterm --> Final Concepts

The final is cumulative. Even if it wasn't though, a lot of the concepts we are going to learn will likely build off of topics and concepts we learned pre-midterm.
by AArmellini_1I
Fri Nov 08, 2019 9:48 am
Forum: Lewis Structures
Topic: Midterm grades
Replies: 26
Views: 473

Re: Midterm grades

Does anyone know the class average on the midterm from last year?
by AArmellini_1I
Wed Nov 06, 2019 10:15 am
Forum: SI Units, Unit Conversions
Topic: units for Equations Sheet
Replies: 2
Views: 138

Re: units for Equations Sheet

I always like to remind myself of the units for J before doing a calculation because for most, if not all, equations the values you use for mass should be in kilograms, distance should be in meters, and time should be in seconds
by AArmellini_1I
Wed Nov 06, 2019 10:10 am
Forum: Lewis Structures
Topic: Line Drawings Outline 3
Replies: 2
Views: 48

Re: Line Drawings Outline 3

I think he is referring to the common way in which people write lewis structures for organic compounds where they leave out H atoms because it is implied? I think he just wants use to be comfortable with them and be able to understand what they imply
by AArmellini_1I
Wed Nov 06, 2019 10:07 am
Forum: Octet Exceptions
Topic: Expanded Octet
Replies: 2
Views: 40

Re: Expanded Octet

Basically you are going to first fulfill the octet rule for all the atoms in the compound. I personally like to add my extra lone pairs to the central atom in order to form the expanded octet first then check the formal charge for each of the atoms. That way you know if you need double or triple bonds
by AArmellini_1I
Fri Nov 01, 2019 1:17 am
Forum: Ionic & Covalent Bonds
Topic: Electronegativity
Replies: 7
Views: 78

Re: Electronegativity

If Lavelle does give us a question asking us to compare the electronegativity between two elements he will have to provide us a periodic table with the corresponding electronegativity values or the values in general
by AArmellini_1I
Fri Nov 01, 2019 1:15 am
Forum: Resonance Structures
Topic: Delocalization vs. Resonance
Replies: 8
Views: 425

Re: Delocalization vs. Resonance

Natalie Benitez 1C wrote:So in terms of delocalization can we say this occurs when atoms form bonds with each other because in a way they are spreading out their electrons through sharing them?
Delocalization just represents a compound's typical behavior of dispersing charges to exterior elements
by AArmellini_1I
Fri Nov 01, 2019 1:13 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr Frequency Condition, Electrons
Replies: 2
Views: 55

Re: Bohr Frequency Condition, Electrons

Just mean that when an electron drops from a certain energy level to another, that electron releases certain energy or light due to the conservation of energy. That light or energy can be calculated Exactly, which is why this change in energy is often represented by a negative value because it's th...
by AArmellini_1I
Fri Nov 01, 2019 1:12 am
Forum: *Black Body Radiation
Topic: Will this concept be tested
Replies: 8
Views: 740

Re: Will this concept be tested

Black bodies won't be tested
by AArmellini_1I
Fri Nov 01, 2019 1:11 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Config for Pd versus Nickel
Replies: 2
Views: 69

Re: Electron Config for Pd versus Nickel

I don't know why specifically in this case this occurs, but Lavelle mentioned that the greater the period the more exceptions to our basic rules.
by AArmellini_1I
Thu Oct 24, 2019 1:53 pm
Forum: DeBroglie Equation
Topic: Help with the concept of De Broglie's
Replies: 8
Views: 515

Re: Help with the concept of De Broglie's

705198479 wrote:what is the formula for wavelength ?

Wavelength = Speed of Light / Frequency
by AArmellini_1I
Thu Oct 24, 2019 1:49 pm
Forum: Ionic & Covalent Bonds
Topic: Cation
Replies: 23
Views: 459

Re: Cation

Also cations and anions have positive/negative charges that can affect the orientation of a molecule (think of water) and affect what molecules they may be attracted too.
by AArmellini_1I
Thu Oct 24, 2019 1:47 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic v.covalent bonds
Replies: 7
Views: 61

Re: Ionic v.covalent bonds

Yep! With that being said you can use the periodic table to determine what bond two elements will likely make
by AArmellini_1I
Thu Oct 24, 2019 1:45 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: HW question
Replies: 3
Views: 81

Re: HW question

You're correct! It's actually an error in the textbook. Lavelle has the explanation under the tab "Solution Manual Errors 7th Edition". With that being said, because Δv = 10.0 m.s-1 then answer is actually Δx = 6.7 x 10-37 m
by AArmellini_1I
Wed Oct 23, 2019 7:46 pm
Forum: Lewis Structures
Topic: Number of valence electrons
Replies: 3
Views: 49

Re: Number of valence electrons

I believe we are covering this either Friday or next week in class!
by AArmellini_1I
Wed Oct 16, 2019 9:19 pm
Forum: *Shrodinger Equation
Topic: Electron Spin
Replies: 2
Views: 39

Re: Electron Spin

Electron spin is just the direction in which the electron rotates (there are two options: up [+1/2] and down [-1/2]). You can almost think of an electron as the earth rotating around the sun, while the Earth rotates around the sun on its orbit in also rotates on its axis. As for what determines the ...
by AArmellini_1I
Wed Oct 16, 2019 9:10 pm
Forum: Quantum Numbers and The H-Atom
Topic: Stern and Gerlach
Replies: 5
Views: 58

Re: Stern and Gerlach

The stern and Gerlach experiment basically consisted of emitted a beam of the same element through a magnetic field and rather than all the atoms continuing on a straight path, some of the electrons curved upwards and the others downwards. Because the n,l, and m(l) variables were all the same it mea...
by AArmellini_1I
Tue Oct 15, 2019 9:30 pm
Forum: DeBroglie Equation
Topic: Calculating Wavelength
Replies: 5
Views: 108

Re: Calculating Wavelength

So first you need to calculate the wavelength of both the proton and electrons with there respective mass. The formula you would use in this case would be: wavelength = h (planck's constant) / (mass x velocity). You kind find in the back of the book that the mass of a proton is (1.673 x 10^-27)kg an...
by AArmellini_1I
Tue Oct 15, 2019 9:21 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydbergs Equation
Replies: 3
Views: 60

Re: Rydbergs Equation

Lavelle also wanted to emphasized how we are subtracting the lower energy level from the higher energy level (such as n=2 - n=1), and how the positive value is expressed as emitted light at unique frequencies, which in emphasized by using his formula.
by AArmellini_1I
Tue Oct 15, 2019 9:17 pm
Forum: Properties of Light
Topic: Defraction patters
Replies: 3
Views: 80

Re: Defraction patters

Yes both light and electrons have wave like properties. As for defraction, it refers to the wave nature of both electrons and light. Lavelle used the example in class of a filter with holes in it and if you shine a beam of electrons/light through the filter the detector on the other side will detect...
by AArmellini_1I
Wed Oct 09, 2019 11:36 am
Forum: Photoelectric Effect
Topic: Quantum
Replies: 5
Views: 82

Re: Quantum

It's like Lavelle described in lecture, we assume water flowing from a facet in continuous but when we zoom in and reduce the flow, eventually gaps begin to form because you're not going to have half a water molecule so to be quantized refers to minimal whole values (n = 1,2,3...)
by AArmellini_1I
Wed Oct 09, 2019 11:32 am
Forum: Balancing Chemical Reactions
Topic: How to write reactions for tests
Replies: 5
Views: 123

Re: How to write reactions for tests

You most likely won't but if you know the state it won't hurt you to include it!
by AArmellini_1I
Wed Oct 09, 2019 11:31 am
Forum: Properties of Electrons
Topic: Changes in Orbitals
Replies: 3
Views: 45

Re: Changes in Orbitals

I had a similar question. I am assuming that because the orbital changes so does both n and the energy so to calculate the energy difference you would use the formulas provided in today's lecture? (I believe we go over orbitals later in this unit so hopefully it will make more sense then)
by AArmellini_1I
Wed Oct 09, 2019 11:27 am
Forum: Student Social/Study Group
Topic: Atomic Spectra: Energy Levels
Replies: 3
Views: 69

Atomic Spectra: Energy Levels

So after sitting through Wednesday's lecture regarding the Atomic Spectra, I just was wondering if all questions regarding the topic would be mainly focused on calculating the change of energy when an electron moves from say n=2 to n=1. Or is there another large part I am missing? Thanks guys!

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