Search found 87 matches

by Ethan Laureano 3H
Sun Feb 21, 2021 11:10 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Which R Values to use
Replies: 21
Views: 48

Re: Which R Values to use

It helps to know your units and write them out so you know if the R-value chosen cancels the units out.
by Ethan Laureano 3H
Sun Feb 21, 2021 11:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cathode/Anode
Replies: 3
Views: 14

Re: Cathode/Anode

All I know is that the anode is for oxidation and the cathode is for reduction. Since conventionally speaking, oxidation is the left cell and reduction is the right, you can think of it as anode is the left and the cathode is on the right.
by Ethan Laureano 3H
Sun Feb 21, 2021 11:03 pm
Forum: Administrative Questions and Class Announcements
Topic: Classes for Biochem Majors
Replies: 6
Views: 31

Classes for Biochem Majors

Hello fellow Biochem majors. I was checking the handbook that we were given during orientation and it suggests I take chem 30A next quarter. However, when I check the pre-reqs of the class, it does not list chem 14B as one? Would I still be able to take this class? Thanks for the help in advance! :)
by Ethan Laureano 3H
Sun Feb 21, 2021 10:56 pm
Forum: Student Social/Study Group
Topic: Fave food
Replies: 99
Views: 204

Re: Fave food

I am craving some Alaskan King crab.
by Ethan Laureano 3H
Sun Feb 14, 2021 10:43 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: ΔH
Replies: 7
Views: 34

Re: ΔH

If you recall the sapling homework, if both delta H and delta S are positive, then the equation would be deltaG = deltaH - TdeltaS. In order to label a reaction spontaneous, deltaG must be negative. At low temperatures, -TdeltaS might not have a high enough magnitude to overcome deltaH and result in...
by Ethan Laureano 3H
Sun Feb 14, 2021 10:38 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: What are the three ways to find Delta H?
Replies: 7
Views: 5285

Re: What are the three ways to find Delta H?

Hess's law, bond enthalpies (least accurate), and standard enthalpies of formation.
by Ethan Laureano 3H
Sun Feb 14, 2021 10:35 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Delta G and Spontaneity
Replies: 10
Views: 27

Re: Delta G and Spontaneity

A positive delta G denotes the need for energy for the reaction, thus indicating it is not spontaneous (occurring without external energy).
by Ethan Laureano 3H
Sun Feb 14, 2021 10:21 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: What's the difference between delta G and delta G°
Replies: 7
Views: 23

Re: What's the difference between delta G and delta G°

Would it be analogous to Q and K, where Q is G and K is Go
by Ethan Laureano 3H
Sun Feb 14, 2021 10:18 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Determining the Sign of S
Replies: 8
Views: 29

Re: Determining the Sign of S

If you are talking about S, then it is only positive values. If you are talking about delta S (which I assume you are), then it would depend on the values used in the equation to derive delta S. You can also think of it conceptually (if it is a phase change from solid to liquid or gas, then degenera...
by Ethan Laureano 3H
Sun Feb 07, 2021 11:07 pm
Forum: Student Social/Study Group
Topic: Post Midterm 1...
Replies: 39
Views: 148

Re: Post Midterm 1...

Go to as many workshops as you can (I know, sounds a lot like Lavelle, but they really help!)
by Ethan Laureano 3H
Sun Feb 07, 2021 11:05 pm
Forum: General Science Questions
Topic: Careless Mistakes
Replies: 54
Views: 233

Re: Careless Mistakes

I would just say take your time and review your work once or twice. And if it is any consolation, the midterms and final will be multiple choice so if you do not see your answer, you know there may be a calculation mistake.
by Ethan Laureano 3H
Sun Feb 07, 2021 11:04 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sapling Week 3/4 #20
Replies: 3
Views: 16

Re: Sapling Week 3/4 #20

Because it is at constant volume. Normally, the change in internal energy would equal work plus q. However, since constant volume denotes no change in volume, work, or
-PdeltaV equals zero. Hope this makes sense.
by Ethan Laureano 3H
Sun Feb 07, 2021 10:56 pm
Forum: Student Social/Study Group
Topic: Superbowl Sunday
Replies: 25
Views: 105

Re: Superbowl Sunday

Sadly it was a pretty disappointing game by the Chiefs. :(
by Ethan Laureano 3H
Sun Feb 07, 2021 10:53 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Relationship between constant volume heat capacity and constant pressure heat capacity.
Replies: 1
Views: 23

Relationship between constant volume heat capacity and constant pressure heat capacity.

Can someone explain the relationship between CV and CP. In Sapling, they say that CP = CV+R. However, other sources, including my TA's discussion say that it is CP = CV+nR. Can someone clarify this? Thank you.
by Ethan Laureano 3H
Sun Jan 31, 2021 10:23 pm
Forum: Student Social/Study Group
Topic: Go treat yourself after MT1!
Replies: 75
Views: 302

Re: Go treat yourself after MT1!

Definitely need to focus on yourself holistically. Know that these 12-14 questions should not ruin your week!
by Ethan Laureano 3H
Sun Jan 31, 2021 10:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Making X negligible
Replies: 34
Views: 97

Re: Making X negligible

When the equilibrium constant is smaller than 10^-4, then you can try. Of course, after trying, check to see if the x value is less than 5% of the initial concentration.
by Ethan Laureano 3H
Sun Jan 31, 2021 10:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: is HClO3 weak or strong? [ENDORSED]
Replies: 49
Views: 244

Re: is HClO3 weak or strong? [ENDORSED]

It helps to memorize the strong acids with this mnemonic: SO I BRought NO CLean CLOthes. Of course you'll also have to remember an additional CLO in HCLO3
by Ethan Laureano 3H
Sun Jan 31, 2021 10:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Kc
Replies: 36
Views: 91

Re: K vs. Kc

K refers to Kp
by Ethan Laureano 3H
Sun Jan 31, 2021 10:06 pm
Forum: Student Social/Study Group
Topic: Best kdrama?
Replies: 30
Views: 179

Re: Best kdrama?

Descendants of the Sun
by Ethan Laureano 3H
Sat Jan 23, 2021 11:43 pm
Forum: Phase Changes & Related Calculations
Topic: bonds and energy
Replies: 13
Views: 84

Re: bonds and energy

Heat is given off in the formation of bonds because energy is given off in the formation of bonds.
by Ethan Laureano 3H
Sat Jan 23, 2021 11:39 pm
Forum: Phase Changes & Related Calculations
Topic: No Heat Change
Replies: 15
Views: 61

Re: No Heat Change

The temperature stays the same because the heat is used to break bonds and thus change phases.
by Ethan Laureano 3H
Sat Jan 23, 2021 11:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Do concentrations change at equilibrium?
Replies: 9
Views: 39

Re: Do concentrations change at equilibrium?

A change in concentrations is considered a stress and the system will work to minimize this stress (add more products or reactants). Otherwise, equilibrium denotes unchanging concentrations.
by Ethan Laureano 3H
Sat Jan 23, 2021 11:35 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard State
Replies: 11
Views: 65

Re: Standard State

Standard state of an element refers to the most stable phase at 1 ATM and the temperature of interest (usually 25 degrees Celsius).
by Ethan Laureano 3H
Sat Jan 23, 2021 11:31 pm
Forum: Phase Changes & Related Calculations
Topic: Vapor vs gas
Replies: 91
Views: 238

Re: Vapor vs gas

So then what would be the difference between vaporization and evaporation? Are they one in the same or are there differences?
by Ethan Laureano 3H
Sun Jan 17, 2021 11:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What makes a weak acid?
Replies: 11
Views: 33

Re: What makes a weak acid?

It is best to memorize as I think it is difficult to derive from knowing the qualifications. That being said, a weak acid will not lose hydrogen protons easily. Additionally, a weak acid will not result in a stable anion. And weak acids typically have short, strong bonds.
by Ethan Laureano 3H
Sun Jan 17, 2021 11:17 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q > K, Q< K
Replies: 25
Views: 100

Re: Q > K, Q< K

Basically, if Q is greater than K, that means that there are more products for Q than K (since products are at the numerator). According to Le Chatelier's principle, when a stress is applied to a system, the system works to counteract it. In this case, when there are more products, then the reaction...
by Ethan Laureano 3H
Sun Jan 17, 2021 11:14 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: q vs k
Replies: 62
Views: 204

Re: q vs k

Q is the products over reactants at any time of the reaction. If Q=K, then the reaction is at equilibrium. If not, you can determine where the reaction will go to (the products side or the reactants side).
by Ethan Laureano 3H
Sun Jan 17, 2021 11:11 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Conjugate acid/base
Replies: 3
Views: 27

Re: Conjugate acid/base

It is best to think of it in terms of KaxKb=Kw. A stronger acid means a higher Ka value. But, when looking at the aforementioned equation, a higher Ka means Kb will be lower.
by Ethan Laureano 3H
Sat Jan 16, 2021 11:07 pm
Forum: Student Social/Study Group
Topic: Motivation
Replies: 34
Views: 175

Re: Motivation

I feel like you should find spaces where you can have fun. Once you do that, you can apply this mentality: "Work hard, play hard". I find myself grinding the week and then looking forward to zoom calls with friends or game nights. This way, I feel like I have earned it.
by Ethan Laureano 3H
Sun Jan 10, 2021 10:05 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 32
Views: 112

Re: Study Tips

-Attend UA workshops -Go to study halls with chem 14b students -Figure out your strengths and weaknesses per unit and watch videos to strengthen those weaknesses -Peruse chemistry community (if you have a question it is likely that someone else has and posted that same question on chem community) -A...
by Ethan Laureano 3H
Sun Jan 10, 2021 9:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K Favors Products or Reactants
Replies: 20
Views: 98

Re: K Favors Products or Reactants

Large K values are anything above 10^3 and small K values are anything below 10^-3
by Ethan Laureano 3H
Sun Jan 10, 2021 9:47 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: reaction quotient
Replies: 6
Views: 33

Re: reaction quotient

The reaction quotient tells us if the reaction is at equilibrium or not (if Q=K). If the reaction is not at equilibrium, the reaction quotient also tells us what side of the equation will the reaction work to form (reactants to products or products to reactants).
by Ethan Laureano 3H
Sun Jan 10, 2021 9:33 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in Pressure
Replies: 9
Views: 42

Re: Change in Pressure

Like many have stated, changing pressure changes concentration because of the change in volume associated. However, not all changes to pressure result or is the result of a change in volume (i.e. adding an inert gas).
by Ethan Laureano 3H
Sun Jan 10, 2021 9:29 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 19
Views: 133

Re: Le Chatelier's Principle

Le Chatelier's principle states that when a stress is applied to a system at equilibrium, the system would react to mitigate the stress. To visualize it more easily, think of an aquarium tank with a divider in the middle and both sides having equal water. If you fill more water on one side, the wate...
by Ethan Laureano 3H
Fri Dec 11, 2020 10:40 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs Angular
Replies: 20
Views: 136

Re: Bent vs Angular

Bent and angular refer to the same molecular geometry (AX2E, AX2E2)
by Ethan Laureano 3H
Fri Dec 11, 2020 10:24 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: Textbook 3f 5
Replies: 6
Views: 64

Re: Textbook 3f 5

You are right that CH3F has a higher dipole moment. However, size and weight trump this. Since iodine is larger and heavier than fluorine (not to mention that there are three of them), the molecule will have stronger LDF and thus a higher melting point.
by Ethan Laureano 3H
Thu Dec 10, 2020 12:17 am
Forum: Identifying Acidic & Basic Salts
Topic: Why Salts of weak bases produce acidic solutions and salts of weak acids produce basic solutions
Replies: 1
Views: 17

Re: Why Salts of weak bases produce acidic solutions and salts of weak acids produce basic solutions

Salts of weak bases produce acidic solutions: When the salt NH 4 Br dissolves in water, it produces the cation (conjugate acid) NH 4 + and the anion (conjugate base) Br - . You have to look at the conjugate pair of the cation and anion. Looking at NH 4 + we know that it is derived from the WEAK BASE...
by Ethan Laureano 3H
Thu Dec 10, 2020 12:05 am
Forum: Bronsted Acids & Bases
Topic: Determining acidic vs basic
Replies: 5
Views: 63

Re: Determining acidic vs basic

To memorize acids you'll just have to memorize (typically they'll have H in the front, but not always). The strong acids are HCl, HBr, HI, H2SO4, HNO3, HClO3, and HClO4. For bases, it's a bit easier. Strong bases are group 1 and 2 hydroxides (OH) and oxides (O).
by Ethan Laureano 3H
Thu Dec 10, 2020 12:00 am
Forum: Hybridization
Topic: hybridization
Replies: 1
Views: 13

Re: hybridization

Hybridization is used to explain why carbon can form 4 bonds with the 4 hydrogen atoms while only having 2 unpaired electrons (from 2p). Since the normal convention states that covalent bonds will share one electron from each atom, then carbon needs to have four unpaired electrons. For this to happe...
by Ethan Laureano 3H
Sat Dec 05, 2020 5:21 pm
Forum: Naming
Topic: oxidation number on sapling question
Replies: 2
Views: 24

Re: oxidation number on sapling question

If you remember, coordination compounds are neutral. With the knowledge that chlorine's charge is 1-, you can derive that the coordination complex (anything in brackets) is 1+. When you know that, then use your knowledge of the ligand charges to figure out the charge of the transition metal. In this...
by Ethan Laureano 3H
Sat Dec 05, 2020 5:01 pm
Forum: Hybridization
Topic: Unhybridized orbitals
Replies: 5
Views: 55

Re: Unhybridized orbitals

I believe unhybridized orbitals arise when there are less regions of electron density than there are valence electrons of the element (but I am only theorizing based on one example: C). When Prof. Lavelle was lecturing about sp2, he used Carbon, an element with four valence electrons. Since there ar...
by Ethan Laureano 3H
Sat Dec 05, 2020 4:53 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Trichloroacetic acid example
Replies: 4
Views: 32

Re: Trichloroacetic acid example

An important thing to know is that p=-log 10 . K A (the dissociation constant) is only really calculated for weak acids. That being said, the stronger K A is the stronger the acid is. In remembering that p=-log 10 , we can derive that pK A =-log 10 K A . In other words, when K A is larger, pK A is s...
by Ethan Laureano 3H
Sat Dec 05, 2020 4:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: linear same atoms?
Replies: 6
Views: 61

Re: linear same atoms?

My preferred method would be to determine the number of electron densities around the central atom and then figure out which ones are bonding pairs and which ones are lone pairs. This requires some memorization or visualization skills. For example, like someone mentioned before, this molecule has fi...
by Ethan Laureano 3H
Sat Dec 05, 2020 2:29 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strong/Weak acids
Replies: 5
Views: 51

Re: Strong/Weak acids

I believe you are correct.
by Ethan Laureano 3H
Sun Nov 29, 2020 12:37 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #3 Bond Angle
Replies: 8
Views: 87

Re: Sapling #3 Bond Angle

You'll just have to memorize. In this case, this results in a square pyramid molecular shape which only has 90 degree bond angles.
by Ethan Laureano 3H
Sun Nov 29, 2020 12:22 am
Forum: Lewis Structures
Topic: Preferential Attractions
Replies: 2
Views: 33

Re: Preferential Attractions

When Lavelle mentions this in his lecture, he wants us to visualize a cation or an anion (something that produces an electrostatic potential) with the molecule who's polarity we are trying to figure out. When he says preferential attraction, he means which part of the molecule would most likely be a...
by Ethan Laureano 3H
Sun Nov 29, 2020 12:06 am
Forum: Sigma & Pi Bonds
Topic: Delocalized π bonds
Replies: 6
Views: 30

Re: Delocalized π bonds

I believe resonance would be the only way delocalized pi bonds exist as resonance describes the delocalization of electrons.
by Ethan Laureano 3H
Sat Nov 28, 2020 11:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Negative poles of molecules
Replies: 3
Views: 45

Re: Negative poles of molecules

Take a look at which is more electronegative. The more electronegative atom is the area which you can consider a negative pole. More specifically, if the net vector of these poles would be where the negative pole is.
by Ethan Laureano 3H
Sat Nov 28, 2020 11:48 pm
Forum: Hybridization
Topic: Confused on hybridization conceptually
Replies: 9
Views: 78

Re: Confused on hybridization conceptually

Hybridization denotes a hybrid of two orbitals. When this occurs, the bonds that use the unpaired electrons in these hybrid orbitals are all of the same energy level. When you figure out hybridization orbitals used, you can figure out what types of bonds are used and consequently the properties of t...
by Ethan Laureano 3H
Sun Nov 22, 2020 10:58 pm
Forum: Hybridization
Topic: Determining Hybridization
Replies: 4
Views: 68

Re: Determining Hybridization

AJForte-2C wrote:Do you need to create an afbau diagram in order to properly determine hybridization, or is it not necessary?

It helps to visualize but I don't think it is necessary. So long as you know the electron density regions and number of orbitals in subshells, you can figure it out.
by Ethan Laureano 3H
Sun Nov 22, 2020 10:50 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: Dipole-Induced-Dipole and Dipole-Dipole
Replies: 10
Views: 149

Re: Dipole-Induced-Dipole and Dipole-Dipole

When it comes to dipole-dipole, both molecules are polar with permanent dipole moments. With dipole-induce-dipole, one is a dipole while the other molecule is not naturally polar. It is only until the electrons of another molecule (in this case the polar one) influence the electrons of the non-polar...
by Ethan Laureano 3H
Sun Nov 22, 2020 10:47 pm
Forum: Ionic & Covalent Bonds
Topic: C-H bond polarity
Replies: 10
Views: 90

Re: C-H bond polarity

You would think that because they are far then it'll be polar. However, when you search up an electronegativity chart, hydrogen is only about .35 less electronegative than carbon. Despite its position in the periodic table, hydrogen actually has a decent electronegativity.
by Ethan Laureano 3H
Sun Nov 22, 2020 10:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining polar molecules
Replies: 7
Views: 65

Re: Determining polar molecules

You'll first determine if polar bonds form. You can figure this out by figuring out if the electronegativity difference between the two atoms is high enough to be considered polar bonds. Next, you will need to determine the net electric dipole moment. To figure this out requires knowing the magnitud...
by Ethan Laureano 3H
Sun Nov 22, 2020 10:37 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Determining Non-Polarity
Replies: 5
Views: 40

Re: Determining Non-Polarity

Hi! There has to be a difference in electronegativity to have a polar bond. Further, there has to be an overall separation of charge, so the negatively charged molecules must be on one side. To add on to what Jessica said, if the polar bonds cancel each other (same magnitude and opposite vector dir...
by Ethan Laureano 3H
Tue Nov 17, 2020 11:16 pm
Forum: Lewis Structures
Topic: NO2 Polarity
Replies: 6
Views: 57

Re: NO2 Polarity

It is polar because of the electronegativity difference between nitrogen and oxygen. As you may know, electronegativity is the tendency of an atom to attract electrons. Because oxygen has a higher electronegativity than nitrogen, and because the difference is large enough, electrons are closer to th...
by Ethan Laureano 3H
Fri Nov 13, 2020 9:59 pm
Forum: Ionic & Covalent Bonds
Topic: Nomenclature
Replies: 6
Views: 28

Nomenclature

Should we know how the molecular formulas when given the names of the molecule. For example, in Sapling there is a question where they ask to draw Lewis Structure of phosphate and phosphite ions as well as nitrate and nitrite ions. Should we know these molecular formulas off the top of our heads for...
by Ethan Laureano 3H
Fri Nov 13, 2020 5:16 pm
Forum: Dipole Moments
Topic: Dipole-dipole vs. ion-dipole vs. ion-ion
Replies: 4
Views: 30

Re: Dipole-dipole vs. ion-dipole vs. ion-ion

Dipole-dipole is when two polar molecules (covalent molecules with unequal sharing of electrons) are attracted together due to electrostatic attraction between a negative and positive dipole. Ionic-dipole is when a cation or anion is attracted to the dipole (negative or positive area due to uneven e...
by Ethan Laureano 3H
Fri Nov 13, 2020 5:09 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8753
Views: 1489602

Re: Post All Chemistry Jokes Here

I'm not sure if this was put already but it is my favorite chemistry joke.

"If Iron Man and Silver Surfer teamed up, they'd be alloys."
by Ethan Laureano 3H
Thu Nov 12, 2020 7:17 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations
Replies: 7
Views: 58

Re: Electron configurations

Also how come Dr. Lavelle said that 4d state is lower energy than 5s state, after 2 e- have occupied 5s state. Based on what you said wouldn't it be the opposite? wouldn't it be that 4d state is lower energy than 5s state before 2 e- have occupied 5s state? When Lavelle says that 4s is lower than 5...
by Ethan Laureano 3H
Thu Nov 12, 2020 6:57 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations
Replies: 7
Views: 58

Re: Electron configurations

Sharon Kim 1A wrote:When writing the electron configurations, I understood it to be written as 3d orbitals before the 4s. Is that the same thing as saying 3d orbitals are filled before 4s?

No. That is purely a stylistic decision. It is the same as writing 4s 3d
by Ethan Laureano 3H
Thu Nov 12, 2020 6:28 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configurations
Replies: 7
Views: 58

Re: Electron configurations

From my understanding, electrons will always fill 4s before 3d. This is because 4s is slightly lower in energy than 3d. It is only when the 3d orbital is filled when 4s is greater in energy than 3d. For this reason, electrons are removed from 4s before 3d.
by Ethan Laureano 3H
Fri Nov 06, 2020 11:35 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Isoelectric atoms
Replies: 9
Views: 38

Re: Isoelectric atoms

Do you mean isoelectronic atoms? If so, then it means having identical electron configurations. So Cl-, Ar, and K+ are all isoelectronic to one another. As for the other characteristics, it depends on whether the trend is affected by the nuclear charge or the atomic radius (how many orbitals). Sorry...
by Ethan Laureano 3H
Fri Nov 06, 2020 1:11 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Lavelle Lecture 11/6
Replies: 2
Views: 30

Re: Lavelle Lecture 11/6

When Lavelle says this, he is referring to the unequal sharing of electrons. If you look at models (search up polar covalent bonds) depicting this, you can see electrons closer to one atom than the other. This results in a negative dipole.
by Ethan Laureano 3H
Fri Nov 06, 2020 1:06 pm
Forum: SI Units, Unit Conversions
Topic: Modules This Week
Replies: 9
Views: 140

Re: Modules This Week

Sadly it doesn't seem like Professor Lavelle updated his modules after the Heisenberg Uncertainty Principle one. He did say that if we enjoy them, he will be willing to create more.
by Ethan Laureano 3H
Fri Nov 06, 2020 12:01 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Change after Z=20
Replies: 2
Views: 28

Re: Change after Z=20

hi! so if you notice on the periodic table, after atomic number 20, we encounter the transitional metals in the d-block. if you can recall from Dr. Lavelle's lectures, this transition to the d-block is significant because in contrast to what we would expect, where an increase in n, the energy level...
by Ethan Laureano 3H
Fri Nov 06, 2020 11:53 am
Forum: Octet Exceptions
Topic: Octet exceptions
Replies: 4
Views: 33

Re: Octet exceptions

From my understanding of the lectures, elements greater than or equal to n=3 can have more than 8 electrons. This is because, when thinking about quantum numbers, you can only have l=2 if n is greater than or equal to 3 (l= 0,1... n-1). And when you have l=2, electrons can fill the d-orbital allowin...
by Ethan Laureano 3H
Sat Oct 31, 2020 6:49 pm
Forum: Quantum Numbers and The H-Atom
Topic: Textbook 1D.13
Replies: 3
Views: 22

Re: Textbook 1D.13

For part a, l starts at 0 and can only go up to n-1. So this means a max of l=6. The values will be l= 0,1,2,3,4,5,6 (7 values). As for ml, it is the values of -l to l. In this case, the l value for d is 2. So the ml will be -2,-1,0,1,2. This corresponds with the 5 orbitals in the d subshell.
by Ethan Laureano 3H
Sat Oct 31, 2020 6:13 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions to Electron Configuration Rules
Replies: 2
Views: 37

Re: Exceptions to Electron Configuration Rules

I believe those are the two main exceptions. I wouldn't know of any more, especially any others Professor Lavelle mentioned.
by Ethan Laureano 3H
Sat Oct 31, 2020 6:11 pm
Forum: Trends in The Periodic Table
Topic: Electron Subshells in Sapling HW #25
Replies: 2
Views: 47

Re: Electron Subshells in Sapling HW #25

I think you are correct in your line of reasoning. It may be that the increased nuclear charge accounts for the size of the atomic radius more than the subshells of the valence electrons.
by Ethan Laureano 3H
Sat Oct 31, 2020 6:08 pm
Forum: Ionic & Covalent Bonds
Topic: Main group elements
Replies: 8
Views: 66

Re: Main group elements

I think they are the groups (columns) 1 and 2 and 13-18. The rest are transition metals and inner transition metals (the two rows at the bottom). As for why they are called main group elements, I am not sure.
by Ethan Laureano 3H
Sat Oct 31, 2020 5:50 pm
Forum: Trends in The Periodic Table
Topic: Oxygen and Ionization Energy
Replies: 9
Views: 66

Re: Oxygen and Ionization Energy

The ionization energy trend is based on how easy it is to remove the electron. Having a greater nuclear charge makes it harder to remove the electron. So, fluorine having a higher ionization energy than oxygen follows the trend. However, the exception can be seen in nitrogen, in which case nitrogen ...
by Ethan Laureano 3H
Fri Oct 23, 2020 12:13 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Post-Module Assessment
Replies: 4
Views: 52

Re: Atomic Spectra Post-Module Assessment

I am pretty sure it is the second one. This is because longer wavelength equates to less energy, and the energy disparity between n=4 and n=2 is greater than from n=5 to n=1.
by Ethan Laureano 3H
Fri Oct 23, 2020 12:09 am
Forum: General Science Questions
Topic: When to use sig figs
Replies: 19
Views: 114

Re: When to use sig figs

I usually write out the full number each time and then apply the sig figs at the end. That way, I can ensure I get the most accurate number.
by Ethan Laureano 3H
Wed Oct 21, 2020 2:31 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Lecture 10/21 Question about H-atom problem
Replies: 3
Views: 21

Re: Lecture 10/21 Question about H-atom problem

That is just the value of the mass of an electron.
by Ethan Laureano 3H
Wed Oct 21, 2020 2:29 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Which Equation should we use?
Replies: 3
Views: 53

Re: Which Equation should we use?

Well Lavelle did introduce the former so I would just stick to that.
by Ethan Laureano 3H
Mon Oct 19, 2020 2:25 pm
Forum: Properties of Light
Topic: Photoelectric Experiment
Replies: 2
Views: 33

Re: Photoelectric Experiment

In fact, this observation that increasing the intensity does not cause ejection of an electron proves that light has this duality of wave and particle. If light only acted as a wave, then increasing the intensity should have ejected the electron (just like how higher ocean waves have a higher knockb...
by Ethan Laureano 3H
Fri Oct 16, 2020 6:01 pm
Forum: Einstein Equation
Topic: wave vs. photons
Replies: 4
Views: 81

Re: wave vs. photons

I believe that all objects have this wave-particle duality. The only reason we don't see it in objects like baseballs or cars is because the momentum of these objects results in a small wavelength (when plugged into the DeBriglie equation). This wavelength is too small for us to register that the ob...
by Ethan Laureano 3H
Fri Oct 16, 2020 5:50 pm
Forum: DeBroglie Equation
Topic: Problem 1B.15
Replies: 3
Views: 52

Re: Problem 1B.15

Taylor K 2C wrote:I believe it is because kg is the fundamental SI unit for mass. But I'm not sure.

Yes. Kg are the standard SI units along with meters for length and seconds for time (to name a few more).
by Ethan Laureano 3H
Thu Oct 15, 2020 3:48 pm
Forum: Photoelectric Effect
Topic: Frequency vs. Intensity
Replies: 16
Views: 131

Re: Frequency vs. Intensity

I liked the analogy Dr. Lavelle gave in his lecture. It is sort of like a cross country team. No matter how many members you have, if not one of them can jump the hurdle, the team is not going to win.
by Ethan Laureano 3H
Wed Oct 14, 2020 12:06 pm
Forum: Properties of Light
Topic: Light intensity for electron ejection
Replies: 7
Views: 65

Re: Light intensity for electron ejection

Professor Lavelle mentioned in the module pertaining to this topic that if you were to double the intensity (double the photons), then you would also double the electrons emitted. Thus, it can be seen in a 1:1 ratio, that is if the energy per photon is high enough.
by Ethan Laureano 3H
Tue Oct 13, 2020 4:05 pm
Forum: DeBroglie Equation
Topic: DeBroglie Concept Help
Replies: 4
Views: 61

Re: DeBroglie Concept Help

Hello! From my understanding of the lectures, De Broglie's concept explain that any moving particle with a momentum has wave properties and so all matter has wave like properties. We only notice these properties in small objects with a high velocity since those with a higher mass (like the baseball...
by Ethan Laureano 3H
Thu Oct 08, 2020 7:11 pm
Forum: Significant Figures
Topic: How to deal with significant figures in decimals with zeros.
Replies: 20
Views: 196

Re: How to deal with significant figures in decimals with zeros.

20.01 has 4 sig figs. As for your base question, when there is a decimal point, all trailing zeros are counted in the sig fig count. However, when there is no decimal point, trailing zeros don't matter. Any zero in between numbers counts, regardless if there is a decimal. So 2001 will also be 4 sig ...
by Ethan Laureano 3H
Wed Oct 07, 2020 2:45 pm
Forum: Significant Figures
Topic: Week 1 Homework #7
Replies: 3
Views: 78

Week 1 Homework #7

The problem tells us that a solution of CaCl2 in water forms a mixture that is 42.0% calcium chloride. It gives us the total grams of the solution (494.6 g) and asks what is the grams for water and calcium chloride. For the sake of the sig figs, I took into account the 42.0% and decided to round my ...
by Ethan Laureano 3H
Wed Oct 07, 2020 2:31 pm
Forum: Significant Figures
Topic: When are sig figs applied?
Replies: 12
Views: 107

Re: When are sig figs applied?

As everyone has stated above, round sig figs at the very end. This way, you prevent any inaccuracy by rounding per step. It may seem tedious to write out the full number every step, but it is needed to ensure accuracy.
by Ethan Laureano 3H
Wed Oct 07, 2020 1:31 pm
Forum: Properties of Light
Topic: Units of Work Function
Replies: 3
Views: 50

Units of Work Function

Can the units for work function be expressed in Joules as well as Joules/mol? If so, which can we expect to encounter more of?
by Ethan Laureano 3H
Mon Oct 05, 2020 5:44 pm
Forum: Balancing Chemical Reactions
Topic: Reaction Terminology "In excess"
Replies: 11
Views: 129

Re: Reaction Terminology "In excess"

I think the key to these problems would be the words "reacts with" as you won't see reactants reacting with products.

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