Search found 43 matches

by kim 4G
Mon Nov 18, 2019 6:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: resonance structures in molecular structures
Replies: 4
Views: 12

Re: resonance structures in molecular structures

Yep. It doesn't matter. In an example in the textbook, only one of the resonance structures of the carbonate ion was used to figure out what the resulting shape of the molecule is.
by kim 4G
Mon Nov 18, 2019 6:31 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: London dispersion
Replies: 4
Views: 19

Re: London dispersion

London dispersion forces are present in between all molecules, despite the fact that those molecules are nonpolar or polar.
by kim 4G
Mon Nov 18, 2019 6:26 pm
Forum: Hybridization
Topic: hybridization
Replies: 4
Views: 15

Re: hybridization

Hybridization further explains the VSEPR model by assuming the mixing of atomic orbitals to help understand why the some bonds have equal lengths when the valence electrons may not be in the same energy level.
by kim 4G
Mon Nov 18, 2019 6:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AXE formula
Replies: 9
Views: 29

Re: AXE formula

A is the central atom. I'm pretty sure it can't have subscripts since there can only be one central atom when we're talking about molecular shape.
by kim 4G
Mon Nov 18, 2019 6:15 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Length
Replies: 9
Views: 54

Re: Test 2 Length

Mandeep Garcha 3C wrote:Just to make sure, hybridization is not on the test right?


Yep. There will be no hybridization on Test 2. That will only be on the final.
by kim 4G
Sun Nov 17, 2019 1:46 am
Forum: General Science Questions
Topic: Test 2 Review
Replies: 8
Views: 77

Re: Test 2 Review

I'm pretty sure that the topics on test 2 will cover: -VSEPR -dipole moments and shape (non-polar/polar) -identifying intermolecular interations -lone pairs and the reason for their locations -sigma and pi bonds Dr. Lavelle also said that whatever we cover in the Monday lecture will also be on the t...
by kim 4G
Tue Nov 12, 2019 2:05 pm
Forum: Quantum Numbers and The H-Atom
Topic: Finding orbitals without given ml quantum number
Replies: 1
Views: 8

Re: Finding orbitals without given ml quantum number

I'm pretty sure the number of orbitals is based on the orbital angular momentum # (l) so for part a), the orbital associated with l=1 is the p-orbital. 2p has three orbitals (since ml= -1, 0, +1).
by kim 4G
Tue Nov 12, 2019 2:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Extra Credit?
Replies: 6
Views: 66

Re: Extra Credit?

I don't think Test 2 topics have been confirmed by any of the TA's nor by Dr. Lavelle just yet. I'm assuming it would cover the rest of Outline 3 (what wasn't on the midterm) and then Outline 4 (Molecular Shape and Structure). Essentially, it should cover everything we go over in lectures that were ...
by kim 4G
Tue Nov 12, 2019 1:58 pm
Forum: Administrative Questions and Class Announcements
Topic: Extra Credit?
Replies: 6
Views: 66

Re: Extra Credit?

From rereading the syllabus, Dr. Lavelle doesn't seem to have any extra credit. Your final grade should be based on the weekly homework, the two tests, the weekly chemistry community, the midterm, and the final. I would just focus on getting all the points you can from these catergories!
by kim 4G
Tue Nov 12, 2019 1:52 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Grades
Replies: 3
Views: 39

Re: Midterm Grades

I don't think Dr. Lavelle will use lecture time to go over the questions on the midterms since we have Test 2 coming up soon. Someone's TA said that the TA's will be handing out the midterms on Wednesday after the lecture.
by kim 4G
Mon Nov 11, 2019 3:44 pm
Forum: Dipole Moments
Topic: Dipoles
Replies: 3
Views: 14

Re: Dipoles

All molecules have dipole forces. However in class, we will most likely only focus on the electric dipole moment (a partial positive charge next to an equal but opposite partial negatvie charge) that are formed by two atoms in a polar covalent bond.
by kim 4G
Mon Nov 11, 2019 12:18 am
Forum: Ionic & Covalent Bonds
Topic: Bond Strength
Replies: 8
Views: 33

Re: Bond Strength

Ionic bonds are stronger because there is a greater electronegativity difference between the two atoms (greater than 2.0). Also, while covalent bonds share electrons, ionic bonds are formed by the mutual attraction from both of the oppositely charged ions.
by kim 4G
Tue Nov 05, 2019 1:40 pm
Forum: Administrative Questions and Class Announcements
Topic: Discussion on Wednesday 11/6
Replies: 2
Views: 20

Re: Discussion on Wednesday 11/6

You still have discussions on 11/6 Wednesday. The only thing cancelled is lecture.
by kim 4G
Tue Nov 05, 2019 1:38 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: +/- speed
Replies: 3
Views: 33

Re: +/- speed

Another way to think about it is to actually subtract and add 5.0 m/s to the given 5.00 m/s. So then the range would be from 0.00 m/s to 10/00 m/s. Therefore, the deltaV would be 10.00 m/s. There is an error in the solutions manual! (Delta V is NOT 5.00 m/s). Make sure you check the link on the chem...
by kim 4G
Tue Nov 05, 2019 1:34 pm
Forum: Photoelectric Effect
Topic: max and min frequency
Replies: 1
Views: 23

Re: max and min frequency

You're right about the kinetic energy being 0. Since you are looking for the minimum frequency needed for the photoejection of an election, there wouldn't be (excess energy) kinetic energy for the ejected eletron. However, the work function would be set equal to hV in order to find the frequency.
by kim 4G
Tue Nov 05, 2019 1:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Class Wed 11/6
Replies: 3
Views: 31

Re: Class Wed 11/6

I'm in the 2:00 pm lecture and Dr. Lavelle mentioned that there is no class that day. Since you're in one of the earlier lecture, he probably forgot to let your lecture know.
by kim 4G
Tue Nov 05, 2019 1:26 pm
Forum: Lewis Structures
Topic: Midterm
Replies: 3
Views: 28

Re: Midterm

Hybridization should be on Test 2, but not on the midterm!
by kim 4G
Mon Oct 28, 2019 10:15 pm
Forum: Ionic & Covalent Bonds
Topic: When is the midterm?
Replies: 5
Views: 40

Re: When is the midterm?

Dr. Lavelle said that he will keep us posted on the location. In terms of the date, he said there could be possible changes if he is unable to reserve a large enough room for all of us.
by kim 4G
Mon Oct 28, 2019 10:14 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Drawing Lewis Structures
Replies: 5
Views: 44

Re: Drawing Lewis Structures

Usually beyond period 3, there are lewis structure exceptions but Boron (in period 2) can also have only 6 electrons bonded to it.
by kim 4G
Mon Oct 28, 2019 10:10 pm
Forum: Ionic & Covalent Bonds
Topic: grading
Replies: 5
Views: 52

Re: grading

Another thing to be aware of is that homework grades are out of 50 points and should be updated weekly by your TA, so don't worry if it seems like full credit was not received.
by kim 4G
Mon Oct 28, 2019 10:06 pm
Forum: Trends in The Periodic Table
Topic: electronegativity table
Replies: 5
Views: 29

Re: electronegativity table

The basic periodic trends would not be provided for us on the tests, but just knowing that electronegativity increases as the elements are closer to the upper right-hand corner of the table should be enough.
by kim 4G
Mon Oct 28, 2019 10:04 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 4
Views: 33

Re: Drawing Lewis Structures

I don't think it would necessarily be considered wrong, but having a lower formal charge means greater stability, so drawing the Lewis Structure accordingly would be the best answer. Probably if the test specifically asks for the Lewis Structure with the lowest formal charge, then drawing out each o...
by kim 4G
Mon Oct 28, 2019 10:00 pm
Forum: Ionic & Covalent Bonds
Topic: How to count valence electrons with the d block
Replies: 4
Views: 23

Re: How to count valence electrons with the d block

Valence electrons in the d block are usually determined by their group number, or the number of electrons in their valence shell. In general, the transitional metals have 2 valence electrons.
by kim 4G
Mon Oct 21, 2019 8:14 pm
Forum: Photoelectric Effect
Topic: Intensity of Light
Replies: 4
Views: 31

Re: Intensity of Light

It is important to consider light as photon packets of energy where a single photon interacts with a single electron. Therefore, each individual photon must have enough energy to remove each electron. Increasing the intensity only increased the number of photons that are hitting the surface of the m...
by kim 4G
Mon Oct 21, 2019 8:06 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spin Quantum Number
Replies: 4
Views: 28

Re: Spin Quantum Number

The spin magnetic quantum number is important because it describes the direction in which the electron spins. There are only two spin states that can be represented with an up or down arrow. A +1/2 is indicated with an up arrow, while -1/2 is indicated with a down arrow. The arrow pointing up can be...
by kim 4G
Mon Oct 21, 2019 7:55 pm
Forum: Photoelectric Effect
Topic: Module Assessment Question
Replies: 2
Views: 28

Re: Module Assessment Question

The correct answer in this case is E=hv since the question is solely asking about the energy of the light and its frequency. Since the question has nothing to do with the energy required to remove an electron from the metal, the only equation you would focus on is the equation of the incoming light ...
by kim 4G
Mon Oct 21, 2019 7:48 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 6
Views: 42

Re: Electron Affinity

Electron affinity of an element is the energy released when an electron is added to a gas-phase atom. In terms of the periodic table, the highest electron affinities can be found toward the right side of the periodic table (especially the upper right near oxygen, sulfur, and the halogens).
by kim 4G
Mon Oct 21, 2019 7:44 pm
Forum: Trends in The Periodic Table
Topic: Atomic Radius
Replies: 3
Views: 29

Re: Atomic Radius

An atomic radius is defined as half the distance between the centers of neighboring atoms. This inclues both ionic and covalent radii as well. A covalent radius is specifically referring to two atoms joined by a chemical bond while an ionic radius refers to the distance between neighboring ions in a...
by kim 4G
Thu Oct 17, 2019 3:46 pm
Forum: Quantum Numbers and The H-Atom
Topic: Ryberg's Constant
Replies: 7
Views: 45

Re: Ryberg's Constant

I would rely more on what Dr. Lavelle has used in class/has provided for us on the constants sheet (R = 3.28984 × 10^15 Hz or 1/s). The Rydberg's constant on Google has a different unit (1/m) and would possibly interfere with the calculations Dr. Lavelle has taught us.
by kim 4G
Thu Oct 17, 2019 3:35 pm
Forum: Photoelectric Effect
Topic: Unit of measurements for E=hv
Replies: 6
Views: 36

Re: Unit of measurements for E=hv

The equation E=hv has the basic units of Joules, but if you think back to the photoelectric effect and the incoming light, the units also refer to the amount of energy per photon. Keeping this in the back of your mind will help you make any conversions that are necessary to figure out how many photo...
by kim 4G
Thu Oct 17, 2019 3:31 pm
Forum: DeBroglie Equation
Topic: DeBroglie Equation Use
Replies: 5
Views: 27

Re: DeBroglie Equation Use

De Brogile's wave equation can be used for any particle with momentum that has wave-like properties with a wavelength. The equation wavelength=h(planck's constant)/(momentum, or the particle's mass times speed) is usually used to find the wavelength of a traveling particle or electron.
by kim 4G
Thu Oct 17, 2019 3:25 pm
Forum: Properties of Light
Topic: EM Spectrum
Replies: 3
Views: 22

Re: EM Spectrum

I don't think it's necessary to memorize every specific wavelength and its regions for the exams, but I would recommend knowing just in general that infrared radiation has the longest wavelengths and that UV radiation has the shortest wavelengths. Also, since Lavelle mentioned that visible light is ...
by kim 4G
Thu Oct 17, 2019 3:21 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisengberg Uncertainty Equation Meaning
Replies: 7
Views: 35

Re: Heisengberg Uncertainty Equation Meaning

The Heisenberg uncertainty principle states that if the location of a particle is known with an uncertainty (delta X), then the momentum of the particle (p) can be also known within the uncertainty of delta p. The equation is usually used to find the minimum uncertainty in the speed (delta v) or the...
by kim 4G
Tue Oct 08, 2019 5:48 pm
Forum: Significant Figures
Topic: Do we use molar mass ?
Replies: 8
Views: 58

Re: Do we use molar mass ?

Are you referring to the molar mass of a compound that is given to you in the problem, or are you referring to the molar masses you use for calculations off the periodic table? If it's the molar mass of a compound that is given in the problem, then I would think you'd take its sig figs into account ...
by kim 4G
Tue Oct 08, 2019 5:42 pm
Forum: Empirical & Molecular Formulas
Topic: Formula Units
Replies: 10
Views: 92

Re: Formula Units

From what I know, formula units can be interchangably used with the number of molecules or atoms, so using Avogadro's number should work for any question asking for a compound's formula units. Something to keep in mind is that formula units usually refer to ionic compounds while molecules refer to m...
by kim 4G
Tue Oct 08, 2019 5:30 pm
Forum: Limiting Reactant Calculations
Topic: Test 1
Replies: 11
Views: 139

Re: Test 1

For extra practice, you could do the examples that are embedded in the readings of the fundamental chapters. However, the listed problems on Outline 1 should be sufficient to prepare you for the test. My TA said that there will be around 7 calculation-based problems for us to answer, so concepts mig...
by kim 4G
Mon Oct 07, 2019 6:02 pm
Forum: Significant Figures
Topic: Homework
Replies: 4
Views: 53

Re: Homework

For week 2, Lavelle gives us the option to complete 5 homework problems from Outline 1 (Fundamentals) or from Outline 2 (The Quantum World). Since the quiz is on Fundamentals/Review material, he told us that doing 5 different homework problems from Outline 1 is acceptable to assist us in studying. H...
by kim 4G
Mon Oct 07, 2019 5:55 pm
Forum: Molarity, Solutions, Dilutions
Topic: Dilutions
Replies: 3
Views: 32

Re: Dilutions

By definition, molarity is the moles of solute divided by the total volume of the solution in liters, so on the test, converting all mL to L before any calculation would be the right thing to do. If the problem gives the a volume in mL, then it would be okay to convert the volume answer found in L b...
by kim 4G
Tue Oct 01, 2019 8:39 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding [ENDORSED]
Replies: 12
Views: 110

Re: Rounding [ENDORSED]

Another thing about rounding at the end of your calculation is that is your last digit is 5, make sure you round to the nearest even number. For example: If you need only 2 sig figs and your answer is 1.35, then your answer would be 1.4. If you had 1.65, then your answer would be 1.6. *Remember that...
by kim 4G
Tue Oct 01, 2019 8:26 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Question on E17c
Replies: 2
Views: 23

Re: Question on E17c

Yep! The answer you got is correct since you do the same calculations for both Fe and Ru. You divide 7.36 x 10^27 atoms of Fe (or in this, Ru as well) by avogadro's number in order to convert the given number of atoms into moles.
by kim 4G
Tue Oct 01, 2019 4:42 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Balancing Equations [ENDORSED]
Replies: 25
Views: 384

Re: Balancing Equations [ENDORSED]

An easy way for me to determine what number to multiple a decimal by to get a whole number is to divide 1 by the decimal. For example: If there are 2.5 mols of C, do 1/0.5 = 2. You should multiply the 2.5 mols by 2 to get a whole number (5). If it's a more difficult value, maybe like 2.125 mols of ...
by kim 4G
Tue Oct 01, 2019 4:33 pm
Forum: Significant Figures
Topic: Sig Figs for Tests/Quizzes
Replies: 7
Views: 52

Re: Sig Figs for Tests/Quizzes

It's probably best to not worry about sig figs until the end of all of your calculations. Since you'd want the most accurate answer at the end, it's better to have as many decimal places when using the calculated values to find your answer. It'd be unnecessary to worry about sig figs through each st...
by kim 4G
Tue Oct 01, 2019 4:26 pm
Forum: SI Units, Unit Conversions
Topic: formula units [ENDORSED]
Replies: 69
Views: 22616

Re: formula units [ENDORSED]

Usually answers should be written in the same unit as the unit presented in the question. Since the unit difference was only a conversion (L to mL), I think both answers would be acceptable as long as the numerical value is correct.

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