Search found 56 matches

Sat Jan 09, 2021 10:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Products and Equilibrium
Replies: 5
Views: 21

Re: Products and Equilibrium

This just means that the products are lower in energy than the reactants, so it makes it more favorable for there to be more products than reactants.
Sat Jan 09, 2021 10:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q and K
Replies: 13
Views: 31

Re: Q and K

Yes, that's correct. Q can be used to see which direction the reaction will go to reach equilibrium. If Q<K it will proceed forward, but if Q>K it will go backwards and form more reactants.
Sat Jan 09, 2021 10:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration
Replies: 12
Views: 36

Re: Concentration

I believe concentrations can't be negative because they measure how much of a substance is present. So if there was none of something, then the concentration would just be 0, not anything in the negatives.
Sat Jan 09, 2021 10:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc and Kp
Replies: 3
Views: 12

Re: Kc and Kp

That's what I have written too, with delta n being the sum of the coefficients of the product minus the sum of the coefficients of the reactants.
Sat Jan 09, 2021 9:57 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pressure and concentration
Replies: 3
Views: 14

Re: pressure and concentration

When the pressure changes, this usually affects the volume as well, and as Dr. Lavelle said, it's not necessarily the pressure that changes the concentration, it's the change in volume. Concentration can be written as moles over volume, so if the volume increases (and pressure decreases), the concen...
Sun Dec 13, 2020 1:26 am
Forum: Student Social/Study Group
Topic: Study methods
Replies: 7
Views: 47

Re: Study methods

Next quarter I'm definitely going to go to more of the UA sessions because those were super helpful. The hardest part about online learning for me is just staying on top of my work, so I'd try to do the textbook problems more ahead of time to prevent getting behind.
Sun Dec 13, 2020 1:21 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity and Bond Angle
Replies: 2
Views: 13

Re: Polarity and Bond Angle

For memorizing the angles, shapes that have 4 regions like tetrahedral and trigonal pyramidal are going to have angles of 109.5 or similar, because of the 4 regions, so I just remember that 4 means 109.5. Shapes that have 3 regions on the same plane like trigonal planar are going to be 120 because 3...
Sun Dec 13, 2020 12:41 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: About electron configurations positive ions of elements in the 4p period (Based on Cu and Cr)
Replies: 2
Views: 16

Re: About electron configurations positive ions of elements in the 4p period (Based on Cu and Cr)

I believe after removing all the p orbital electrons you remove the s orbital electrons next and then the d orbital but I'm not fully sure, hopefully someone else can confirm.
Sun Dec 13, 2020 12:30 am
Forum: Bronsted Acids & Bases
Topic: HClO3 Strong Acid
Replies: 4
Views: 49

Re: HClO3 Strong Acid

I had this question too. I was thinking that it was a strong acid but that note confused me so I'm not 100% sure.
Sat Dec 12, 2020 10:02 pm
Forum: Hybridization
Topic: hybrid orbitals
Replies: 4
Views: 17

hybrid orbitals

When naming hybrid orbitals do we have to put the orbital number before it? Like does we have to specify that it's 2sp^3 or is it just sp^3 for example.
Sun Dec 06, 2020 9:38 pm
Forum: Naming
Topic: Naming a compound
Replies: 9
Views: 94

Re: Naming a compound

I also have a hard time naming the compounds, but I've heard that just practicing a lot and memorizing as well as you can can help in becoming faster at it.
Sun Dec 06, 2020 9:29 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Detrmining Shape from coordination numbers
Replies: 6
Views: 34

Re: Detrmining Shape from coordination numbers

If I'm understanding it correctly, the coordination number is roughly how many attachments can be found on the central atom. So if the coordination number is 4, the geometries that include 4 attachments would be most commonly used.
Sun Dec 06, 2020 9:24 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 5
Views: 21

Re: Coordination Number

To simplify it, I just think of the coordination number as how many atoms or other molecules are connected to the central atom. In this case the 5 NH3 molecules are connected and the 1 SO4 molecule is connected, so total there are 6, making the coordination number 6.
Sun Dec 06, 2020 9:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: angles Q.21 2E
Replies: 3
Views: 13

Re: angles Q.21 2E

He mentioned this in lecture, but I believe we don't need to memorize the exact number, just that it's slightly less than 109.5.
Sun Dec 06, 2020 9:16 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 4
Views: 26

Re: Coordination Number

This might be oversimplifying it, but I just remember that each en contributes 2 to the coordination number and each edta contributes 6 to the coordination number. I think we just have to memorize it but correct me if I'm wrong!
Sun Dec 06, 2020 9:09 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Determining Oxidation Numbers
Replies: 6
Views: 28

Re: Determining Oxidation Numbers

I have some trouble with this too, but normally I just think of it like an equation! Each atom has its own charge, and the molecule as a whole has a charge, and the sum of the charges of the atoms needs to equal the charge of the molecule. Normally all the atoms except the one you're looking for has...
Mon Nov 30, 2020 4:57 am
Forum: Resonance Structures
Topic: Stable Resonance Structures
Replies: 4
Views: 33

Re: Stable Resonance Structures

As of what we've learned so far I think the biggest thing to look at is the formal charge if the question doesn't give you any more info. The structure with the least number of formal charges is most stable. I also believe that the structure with the least separation of formal charge is more stable ...
Mon Nov 30, 2020 4:50 am
Forum: Lewis Structures
Topic: Sapling #20
Replies: 7
Views: 36

Re: Sapling #20

Hi, I think that because it's the same element with the same electronegativity that's on all the sides, it cancels out. I was kind of confused on whether or not the charges would affect the polarity too but I don't think it does because then it would seem to be polar.
Mon Nov 30, 2020 4:44 am
Forum: Resonance Structures
Topic: finding resonance structures
Replies: 4
Views: 39

finding resonance structures

Hi, I sometimes struggle with finding the resonance structures for certain molecules, does anyone have any tricks that help you easily make all the structures?
Sun Nov 29, 2020 1:15 am
Forum: Sigma & Pi Bonds
Topic: pi bonds
Replies: 13
Views: 107

pi bonds

Hi! Does anyone have any tips for better visualizing how pi bonds work? I understand the basics but I'm having a hard time picturing them. Thank you!
Sun Nov 22, 2020 11:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angle tips
Replies: 10
Views: 64

bond angle tips

Does any one have any tips for remembering the bond angles or is it just somethings that needs to be memorized as is?
Sun Nov 22, 2020 11:36 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: determining viscosity
Replies: 11
Views: 96

Re: determining viscosity

Without doing an experiment, you can compare viscosities by looking at the IMF's of the substances. If a substance has high IMF's they will be closer together and more viscous. If it has low IMF's, the molecules won't be as attracted to each other and farther apart, so it will be less viscous.
Sun Nov 22, 2020 11:32 pm
Forum: Lewis Structures
Topic: Octet Rule
Replies: 17
Views: 129

Re: Octet Rule

I have this issue a lot too, but I know that the octet rule can be defied for certain elements. In some cases, the d orbitals can accept electrons as well, which allows some elements like sulfur and chlorine to have more than 8. I'm not sure what the exact rules for this are, but hopefully someone e...
Sun Nov 22, 2020 11:08 pm
Forum: Trends in The Periodic Table
Topic: Exceptions to Trends in atomic radius
Replies: 1
Views: 24

Re: Exceptions to Trends in atomic radius

I have read that Sb is slightly larger than Sn, but I'm not sure if this is true because I can't seem to find any more information on it
Sun Nov 22, 2020 11:01 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent Bonds
Replies: 7
Views: 31

Re: Ionic and Covalent Bonds

If you know how the electron is being shared, or if it's being given up and given to the other atom that's another way to tell if it's polar covalent or ionic, but mostly it's looking at the electronegativities or what kind of elements it's between (like metal or nonmetal).
Sun Nov 15, 2020 11:03 pm
Forum: Lewis Structures
Topic: expanded octets
Replies: 2
Views: 12

expanded octets

Can someone please explain how we know when an atom will use the expanded octet? I know which atoms can I just get confused on knowing when it will use it if at all. Thank you!
Sun Nov 15, 2020 9:59 pm
Forum: Ionic & Covalent Bonds
Topic: Between 1.5 and 2
Replies: 3
Views: 36

Re: Between 1.5 and 2

I believe that if the electronegativity difference is more than 1.7 it will be an ionic bond and .5-1.7 is a polar bond, so for the lewis structure for an ionic bond you would draw the two ions separate, and for the polar bonds it would be the normal lewis structure. I'm not 100% sure though so hope...
Sun Nov 15, 2020 9:26 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: polar vs nonpolar
Replies: 3
Views: 31

Re: polar vs nonpolar

First look at whether the bonds are polar or not by looking at electronegativity, and if there are no polar bonds then the molecule is non polar. If there are polar bonds, look at the arrangement of the molecule and if it is not symmetrical, then the molecule is polar. I have a hard time with this t...
Sun Nov 15, 2020 9:19 pm
Forum: Lewis Structures
Topic: Sapling 9
Replies: 8
Views: 75

Re: Sapling 9

For formal charge the most probable structures are the ones with the least amount of formal charges on the individual atoms (as long as it still adds up to the total charge), and for bond length, it says that experimentally it was found that the bond length was 144 which is close to 140, the bond le...
Sun Nov 15, 2020 1:00 am
Forum: Lewis Structures
Topic: Lewis structure based on oxidation #
Replies: 2
Views: 39

Lewis structure based on oxidation #

Hi! Can someone please explain how to find which lewis structure is best based on the oxidation number of the central atom? (like number 9 on sapling) Thank you!
Sun Nov 08, 2020 11:11 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Explaining Electron Configuration
Replies: 4
Views: 15

Re: Explaining Electron Configuration

I think of it as counting up the number of electrons in an element. The metals on the left side of the periodic table have electrons in the s orbital (1s^1, 1s^2, 2s^1, 2s^2...) and these can only go up to _s^2. The 6 groups on the right side are the p orbital and the exponent can go up to 6 because...
Sun Nov 08, 2020 10:50 pm
Forum: Resonance Structures
Topic: formal charge
Replies: 5
Views: 15

Re: formal charge

Yes, I believe the formal charges should add up the charge of the molecule as a whole. I think certain atoms are more likely to be negative or positive based on their electronegativities, but I don't know if chlorine for example would always have to be negative, even though it usually is because it ...
Sun Nov 08, 2020 10:16 pm
Forum: Trends in The Periodic Table
Topic: Ionization and electron affinity
Replies: 6
Views: 44

Re: Ionization and electron affinity

Ionization energy is the amount of energy that is required to remove an electron, and more specifically the least bound electron to the atom. Elements that only have one valence electron have lower ionization energies because removing the one electron would make it have a full outer shell. As you mo...
Sun Nov 08, 2020 10:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: Pz Py Pz
Replies: 5
Views: 42

Re: Pz Py Pz

They represent the different orientations of the electrons in the atom. They are the different orbitals in the p subshell, so basically the three different positions of those electrons.
Sun Nov 08, 2020 10:05 pm
Forum: Electronegativity
Topic: polyatomic ions
Replies: 4
Views: 32

Re: polyatomic ions

I believe it comes down to the electronegative of the atoms, so it depends on which you're looking at. The more electronegative it is compared to the atoms it is bonded to the more likely it is to follow the trends seen on the periodic table, (like oxygen having a -2 charge).
Sun Nov 08, 2020 9:58 pm
Forum: Lewis Structures
Topic: nitrate lewis structure
Replies: 7
Views: 57

Re: nitrate lewis structure

Hi! I believe this is because it would cause nitrogen to have 5 bonds, the two double bonds and a single bond, which wouldn't be very stable.
Sun Nov 08, 2020 6:08 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration for Ions
Replies: 1
Views: 11

Re: Electron Configuration for Ions

Hi Stella! I had this question too. I've been doing what the UA said and starting from the previous noble gas, but I'm not sure if both are correct or if one is preferred.
Mon Nov 02, 2020 12:02 am
Forum: Student Social/Study Group
Topic: How to relax
Replies: 108
Views: 559

Re: How to relax

Usually I just watch tv or workout, (which isn't very relaxing sometimes), but I've been trying to do yoga recently and it's pretty fun!
Mon Nov 02, 2020 12:00 am
Forum: SI Units, Unit Conversions
Topic: Converting equations
Replies: 14
Views: 123

Re: Converting equations

Hi, I come across this problem a lot too, but it helps me to write out each equation with units every step of the way, without skipping steps. Hope it helps!
Sun Nov 01, 2020 11:46 pm
Forum: DeBroglie Equation
Topic: sapling homework
Replies: 4
Views: 48

sapling homework

Can someone please explain how to start this problem? The incident radiation had a wavelength of 1064 nm, and the ejected electrons were found to have an energy of 0.137 eV. The electron affinity is the difference in energy between the incident photons and the energy of the ejected electrons. Determ...
Sun Nov 01, 2020 6:13 pm
Forum: Quantum Numbers and The H-Atom
Topic: electrons in an atom
Replies: 2
Views: 21

electrons in an atom

Can someone please explain how to find the number of electrons in an Atom based on the Quantum number? I'm getting stuck on what the l means and how it factors into how many electrons there are. Thank you!
Sun Nov 01, 2020 5:00 pm
Forum: Student Social/Study Group
Topic: Favorite TV shows
Replies: 176
Views: 824

Re: Favorite TV shows

I've been watching Lucifer on Netflix! Really funny, gets interesting and I think another season is coming out soon!
Sun Oct 25, 2020 10:49 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect-Work Function
Replies: 4
Views: 36

Re: Photoelectric Effect-Work Function

This has been confusing me too, but I believe work function is the energy needed to remove an electron from a surface, and this energy must match the energy of the photon for the electron to be removed. I think the problem has to give you the work function if you are supposed to use it, or if you kn...
Sun Oct 25, 2020 10:42 pm
Forum: Properties of Electrons
Topic: Circular Standing Wave
Replies: 2
Views: 30

Re: Circular Standing Wave

I'm not sure if this is what you're asking, but I believe an electron cannot be in between energy levels, if it doesn't have enough energy it will just remain at the lower energy level. Not too sure about the circular standing wave I was curious about that too.
Sun Oct 25, 2020 10:22 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 9
Views: 76

Re: Covalent Bonds

Hydrogen bonds are the weakest, and I believe ionic bonds tend to be stronger than covalent because of the different charges on the ions and the electronegativity differences, except when placed in water or some solution covalent bonds are stronger.
Sun Oct 25, 2020 9:56 pm
Forum: Einstein Equation
Topic: Sapling hw #7
Replies: 2
Views: 35

Sapling hw #7

Hi! I had a question of one of the problems from sapling which is, suppose the typical work function of the metal is roughly 4.170×10−19 J. Calculate the maximum wavelength in angstroms of the radiation that will eject electrons from the metal. What would be the first step to solve this? I tried loo...
Sun Oct 18, 2020 11:30 pm
Forum: Administrative Questions and Class Announcements
Topic: Notetaking and Organization
Replies: 7
Views: 48

Re: Notetaking and Organization

Since most of the topics relate to each other in some way, I've just been compiling everything into one document. I make sure I label everything appropriately so it is easy to find later on. The only thing that helps me retain information better is repetition and practice so I go over my notes multi...
Sun Oct 18, 2020 11:21 pm
Forum: Properties of Electrons
Topic: Energy per Photon
Replies: 7
Views: 39

Re: Energy per Photon

If I understand your question and the topic correctly, then the energy required to remove an electron would be the lowest the energy of the photon could be. So if the photon is going to remove the electron it must have the same or more energy than the required energy. I'm not sure if you can assume ...
Sun Oct 18, 2020 11:16 pm
Forum: Einstein Equation
Topic: Particles with mass
Replies: 5
Views: 25

Re: Particles with mass

Adding onto what everyone else said, because photons have no mass, they get all their energy from their momentum. Which is why light is never at rest if I'm correct.
Sun Oct 18, 2020 11:07 pm
Forum: Properties of Light
Topic: Intensity vs amplitude
Replies: 6
Views: 60

Re: Intensity vs amplitude

From what I've read as well, intensity is the square of the amplitude so they are proportional but not the same thing. They are both related to the amount of energy a wave has.
Sun Oct 18, 2020 11:01 pm
Forum: Properties of Electrons
Topic: Energy levels
Replies: 8
Views: 56

Re: Energy levels

The gaps become smaller as energy levels increase because the farther away from the nucleus the electrons are the less the pull from the protons is. So the farther away the electron is the less energy is needed, so the gaps decreases.
Sun Oct 11, 2020 4:01 pm
Forum: SI Units, Unit Conversions
Topic: Unit Conversion Tips
Replies: 5
Views: 41

Re: Unit Conversion Tips

When converting units it makes it easier for me to write them all out as fractions so I can see and make sure the appropriate ones cancel out. That way I can easily see which units go where. I usually convert before calculating but am not sure if it can be done after as well.
Sun Oct 11, 2020 3:23 pm
Forum: Empirical & Molecular Formulas
Topic: Molecular Formula
Replies: 3
Views: 37

Re: Molecular Formula

You have to find the molar mass of the empirical formula and the molar mass of the molecular formula and then find the ratio between them. Then you multiply that by the number of atoms in the empirical formula. So if the molar mass of the molecular formula is 3x as much as the molar mass of the empi...
Sun Oct 11, 2020 3:18 pm
Forum: SI Units, Unit Conversions
Topic: Conversion Factors
Replies: 6
Views: 35

Re: Conversion Factors

I believe he mentioned that on tests we will be given conversion factors and some formulas but I could be mistaken.
Sun Oct 11, 2020 3:10 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Combustion Reactions
Replies: 6
Views: 76

Re: Balancing Combustion Reactions

From what I know, the things that make it a combustion reaction are that a hydrocarbon is reacting with oxygen to produce H20 and CO2. So yes I assume its always a variation of said compounds and only applicable to hydrocarbon compounds.
Sat Oct 10, 2020 2:48 pm
Forum: Limiting Reactant Calculations
Topic: Last Question on the Sapling Hw (Week 1)?
Replies: 12
Views: 154

Re: Last Question on the Sapling Hw (Week 1)?

I had the same question. Even when looking at the hint I was confused because it seemed like we had to look up the molar mass of 2-butanone. I wasn't sure if there was a way to find this without looking it up. It makes sense once I know the molar masses but does anyone know if we're supposed to just...