Search found 35 matches

by Reagan Smith 1H
Sun Nov 17, 2019 9:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Geometry versus shape
Replies: 3
Views: 17

Geometry versus shape

What are the differences between molecular geometry and molecular shape?
by Reagan Smith 1H
Sun Nov 17, 2019 9:28 pm
Forum: Bronsted Acids & Bases
Topic: Test2
Replies: 7
Views: 28

Re: Test2

It will cover everything from after the midterm to the material we just learned on Friday, and they will test on shapes so my TA highly recommended making flashcards to go through and make sure you can determine all of the shapes we have learned.
by Reagan Smith 1H
Sun Nov 17, 2019 9:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar vs. Nonpolar
Replies: 8
Views: 18

Re: Polar vs. Nonpolar

If the dipoles of two atoms are pointing in the same direction (such as the hydrogens in water) the dipoles do not cancel out and therefore water is polar, but if two vectors do cancel, the molecule is nonpolar.
by Reagan Smith 1H
Sun Nov 17, 2019 9:23 pm
Forum: Dipole Moments
Topic: How to tell
Replies: 1
Views: 12

How to tell

How can you tell which kind of dipole interaction is going on? Like dipole-dipole, induced dipole-induced dipole, etc?
by Reagan Smith 1H
Sun Nov 17, 2019 9:20 pm
Forum: Bond Lengths & Energies
Topic: Electron Density
Replies: 10
Views: 21

Re: Electron Density

Yes, I believe that lone pairs of electrons are considered regions of electron density since they influence the molecular shape. Please see the attached image. Thank you so much! Do you think we are going to have to know all of the shapes? I think we are supposed to know all of the shapes we have c...
by Reagan Smith 1H
Sat Nov 09, 2019 12:49 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: instantaneous dipoles
Replies: 3
Views: 15

Re: instantaneous dipoles

I don't know which one is "more important" per se, but Dr. Lavelle pointed out that while shape impacts the difference in boiling/melting points, the number of electrons impacts it more drastically.
by Reagan Smith 1H
Sat Nov 09, 2019 12:46 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 4
Views: 21

Re: Lewis Structures

You put the negative formal charge on the more electronegative atom.
by Reagan Smith 1H
Fri Nov 08, 2019 7:38 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Magnetic Quantum numbers
Replies: 12
Views: 63

Re: Magnetic Quantum numbers

The magnetic quantum number can be determined by the angular momentum quantum number. ml can be from -l to l.
E.g. If l=2, ml can be -2,-1,0,1,2.
by Reagan Smith 1H
Fri Nov 08, 2019 7:34 pm
Forum: Trends in The Periodic Table
Topic: atomic radius
Replies: 7
Views: 26

Re: atomic radius

It decreases across a period because the electrons are in the same orbital across a period but the number of protons increases across a period, so the pull from the positive nucleus on the negative electrons pulls the electrons closer, decreasing radius.
by Reagan Smith 1H
Fri Nov 08, 2019 5:47 pm
Forum: Student Social/Study Group
Topic: Midterm
Replies: 3
Views: 33

Re: Midterm

Since you were provided the mass of the compound, I think it was riboflavin, and you had the mass of each of the products, H 2 O, CO 2 , and N 2 , plus you had the balanced chemical equation , you could solve for the number of moles of C in CO 2 using a conversion factor of 1 mol C per one mol CO 2 ...
by Reagan Smith 1H
Fri Nov 08, 2019 5:39 pm
Forum: Photoelectric Effect
Topic: Frequency and number of electrons ejected
Replies: 2
Views: 13

Re: Frequency and number of electrons ejected

No, increasing frequency of the light does not change the number of electrons ejected from a metal surface. Once the minimum frequency required to eject an electron is met, other electrons will be ejected as long as the frequency stays at that threshold level or above it. In order to eject more elec...
by Reagan Smith 1H
Fri Nov 08, 2019 5:34 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: Dispersion
Replies: 3
Views: 10

Dispersion

How does dispersion explain why the three hydrocarbons in the picture in the lecture today (pentane, pentadecane, octadecane) all had different viscosities? I understand that they all have a different number of carbons but how does that play a role in dispersion?
by Reagan Smith 1H
Fri Nov 08, 2019 5:30 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: Difference in terminology
Replies: 1
Views: 14

Difference in terminology

Dr. Lavelle said that Induced dipole-induced dipole, London, Dispersion, and Van de Waals are all interchangeable but also said they have some differences. What are the differences and why can we call them interchangeable?
by Reagan Smith 1H
Wed Nov 06, 2019 12:33 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr Frequency Condition
Replies: 1
Views: 29

Bohr Frequency Condition

What does the Bohr Frequency condition explain or prove?
by Reagan Smith 1H
Sun Oct 27, 2019 4:17 pm
Forum: Lewis Structures
Topic: Dots vs Lines in Lewis Structures
Replies: 6
Views: 37

Re: Dots vs Lines in Lewis Structures

Using lines helps to show that there is a covalent bond because it represents the sharing of electrons while dots represent lone pairs of electrons in covalent bonds. In ionic bonds, you do not use lines because there is no sharing of electrons.
by Reagan Smith 1H
Sun Oct 27, 2019 4:10 pm
Forum: Bond Lengths & Energies
Topic: C-C bond lengths
Replies: 4
Views: 17

C-C bond lengths

In his example of resonance in benzene, Dr. Lavelle drew a resonance structure and labeled the length of the double bond between two carbons as 1.34Å and the length of the single bond between two carbons as 1.54Å. Then he went on to say that experimentally observed C-C bond lengths all equal 1.39Å. ...
by Reagan Smith 1H
Sun Oct 27, 2019 4:04 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Shielding
Replies: 3
Views: 13

Re: Electron Shielding

Electron shielding is just the concept that electrons closer to the nucleus act as a shield to those further from the nucleus, making the outermost electrons have less of a pull toward the positive nucleus because the magnetic pull is basically being blocked by the closer electrons.
by Reagan Smith 1H
Sun Oct 27, 2019 4:01 pm
Forum: Lewis Structures
Topic: Ionic vs. Covalent Lewis Structures
Replies: 2
Views: 32

Re: Ionic vs. Covalent Lewis Structures

Lewis structures for covalent bonding use lines to represent the sharing of electrons. Lewis structures for ionic bonding do not use lines because electrons are either lost or gained, not shared, so the dots (aka electrons) are moved from one element to the other to represent bonds, and brackets are...
by Reagan Smith 1H
Sun Oct 27, 2019 3:51 pm
Forum: Resonance Structures
Topic: Determining Resonance
Replies: 3
Views: 14

Determining Resonance

How do you determine which resonance structure is the most stable?
by Reagan Smith 1H
Sun Oct 20, 2019 4:27 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: What does the H mean?
Replies: 9
Views: 42

Re: What does the H mean?

The h with the dash through the stem is planck's constant divided by 2 times pi, which is equal to h/2π
by Reagan Smith 1H
Sun Oct 20, 2019 4:24 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spin
Replies: 3
Views: 21

Re: Spin

It is not that it necessarily affects the behavior of the electron, but it is to even out the magnetic field created by the positive nucleus with the negative electrons. If electrons are in the same orbital, the spins must be opposite. If they are in different orbitals, they must be parallel, theref...
by Reagan Smith 1H
Sun Oct 20, 2019 12:30 pm
Forum: Properties of Electrons
Topic: Wave-like and particle-like properties
Replies: 7
Views: 36

Wave-like and particle-like properties

Does every single thing have both wave-like and particle-like properties? Or do only things that are quantized have wave-like properties?
by Reagan Smith 1H
Sun Oct 20, 2019 12:23 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 9
Views: 56

Re: Work Function

If you are talking about work function and threshold energy rather than threshold frequency, they are virtually the same thing, nearly interchangeable. Threshold energy is the minimum amount of energy needed to eject an electron from a metal surface, and that is denoted by the work function.
by Reagan Smith 1H
Fri Oct 18, 2019 8:44 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: How to Name Electron Configurations
Replies: 5
Views: 19

Re: How to Name Electron Configurations

I believe both ways will be sufficient in the class but to find out what element you use to write the shorthand version, you use the noble gas (the elements in the rightmost columns on the periodic table) that is in the row above the element you are writing the configuration for.
by Reagan Smith 1H
Fri Oct 11, 2019 5:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Negative Energy Value for Hydrogen Energy Levels
Replies: 2
Views: 13

Re: Negative Energy Value for Hydrogen Energy Levels

From what Dr. Lavelle described on Wednesday, the reference point for the energy of an electron is 0 because we assume it is not interacting with anything. The negative energy of the electron represents that an electron bound to an atom has a lower energy than that of a "free" electron, on...
by Reagan Smith 1H
Fri Oct 11, 2019 3:22 pm
Forum: Properties of Electrons
Topic: Circular Standing Wave
Replies: 3
Views: 28

Circular Standing Wave

Today in the lecture we were told that an electron is described as a circular standing wave around the nucleus. How does this describe why electrons have quantized energy states in atoms? Dr. Lavelle said it was from the line spectra but I do not understand how this is modeled.
by Reagan Smith 1H
Thu Oct 10, 2019 3:56 pm
Forum: Limiting Reactant Calculations
Topic: general questions
Replies: 11
Views: 120

Re: general questions

Finding the limiting reactant allows you to find out how much product you will be able to make because the limiting reactant will run out the fastest, determining how much product is made. The next step would generally to find out how much of the product can be produced based on how much of the limi...
by Reagan Smith 1H
Thu Oct 10, 2019 3:48 pm
Forum: Properties of Light
Topic: Energy of light
Replies: 4
Views: 32

Energy of light

Is it always true that light with shorter wavelengths have higher energy? And why would that be?
by Reagan Smith 1H
Thu Oct 10, 2019 3:40 pm
Forum: Photoelectric Effect
Topic: threshold energy
Replies: 4
Views: 35

Re: threshold energy

Threshold energy, also called work function, is the energy needed to remove an electron from a metal surface using a light.
by Reagan Smith 1H
Thu Oct 03, 2019 10:22 pm
Forum: Significant Figures
Topic: Sig Fig Addition and Subtraction
Replies: 5
Views: 58

Sig Fig Addition and Subtraction

If there is a problem that includes addition/subtraction AND multiplication/division, which sig fig rule is supposed to be followed since there are different rules?
by Reagan Smith 1H
Wed Oct 02, 2019 11:11 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Equations Formatting
Replies: 6
Views: 70

Re: Balancing Chemical Equations Formatting

You should interpret that as 1 Mg and 6 N since the parentheses do not surround the Mg at all
by Reagan Smith 1H
Wed Oct 02, 2019 11:03 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar Mass
Replies: 10
Views: 65

Re: Molar Mass

If you are given the substance you should be able to figure out the molar mass by using the periodic table. You just need to figure out how many of each element you have so that you can multiply the molar mass of one atom of that element by the total number in the formula and add it all together for...
by Reagan Smith 1H
Wed Oct 02, 2019 10:59 pm
Forum: Ideal Gases
Topic: Reading the textbook [ENDORSED]
Replies: 129
Views: 75184

Re: Reading the textbook [ENDORSED]

The textbook definitely has some valuable information that goes in depth on all of the topics covered so I think it is definitely worth it to read the book and view the examples. The examples are super helpful.
by Reagan Smith 1H
Wed Oct 02, 2019 10:51 pm
Forum: SI Units, Unit Conversions
Topic: Sig figs
Replies: 18
Views: 137

Re: Sig figs

I think you are supposed to do the sig figs only at the end so that your rounding doesn't get messed up but if you want to be super sure Dr. Lavelle has a Sig Fig review link on his 14A website

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