Search found 28 matches

by Garrett Dahn 1I
Sun Jun 03, 2018 11:51 pm
Forum: Dipole Moments
Topic: dipole moments
Replies: 9
Views: 338

Re: dipole moments

One thing I think is important to generally note here as we are talking about polarity is that the differences in electronegativity merely suggest the relative polarity of a molecule. By that I mean to say that ionic bonds are not fundamentally, irrevocably different covalent bonds, but are rather a...
by Garrett Dahn 1I
Sun Jun 03, 2018 11:44 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 2
Views: 107

Re: Ligands

Ligands are important to us because of their ubiquity in biological molecules, as they are responsible for a great number of chemical and biological reactions. They bind to transition metals via coordinate bonding and make accessible the continued bonding of those molecules so that these aforementio...
by Garrett Dahn 1I
Sun Jun 03, 2018 11:37 pm
Forum: Lewis Acids & Bases
Topic: Acids/Bases and Lewis Acids/Bases
Replies: 2
Views: 94

Re: Acids/Bases and Lewis Acids/Bases

I'd imagine the idea of an acid and a base in chemistry has to do with an acid being the acceptor and the base being the donor -- Gilbert Lewis' work was related specifically to electron behavior. I'm pretty sure this just has to do with Lewis' namesake and the fact that acids are known to be accept...
by Garrett Dahn 1I
Sun May 27, 2018 11:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar VS Nonpolar shapes
Replies: 4
Views: 144

Re: Polar VS Nonpolar shapes

Sylvie-- The dipole moments of non polar molecules will cancel out insofar as the individual dipole vectors will literally cancel out: two perfectly horizontal dipole vectors going in opposite directions ( --> <--) would, for example, cancel out. The vectors cancel the way a vector in physics might ...
by Garrett Dahn 1I
Sun May 27, 2018 11:44 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Exponent
Replies: 5
Views: 376

Re: Formal Charge Exponent

I think the entire molecule takes on a negative charge because one of its components has a negative charge, and since molecules consist of atoms, if one of those is charged, the molecule in turn will be the sum of those charges. So the negative charge is on that particular atom, but the entire molec...
by Garrett Dahn 1I
Sun May 27, 2018 11:41 pm
Forum: Sigma & Pi Bonds
Topic: Bond Strength/Bond Type
Replies: 3
Views: 239

Re: Bond Strength/Bond Type

Hey Gabi-- I think the main difference between sigma and pi bonds has to do not so much with their strength as their orientation and structure. Sigma bonds are more difficult to break not because they are necessarily stronger bonds, but because they are situate atoms in a way which allows the two at...
by Garrett Dahn 1I
Sun May 20, 2018 11:16 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen bonds vs. dipole-dipole bonds
Replies: 2
Views: 84

Re: Hydrogen bonds vs. dipole-dipole bonds

In lecture, Dr. Lavelle gave the following values for these bonds: Dipole-dipole bonds: -2 kJ.mol-1 Ion-dipole bonds: -15 kj ... and did not give a specific value for Hydrogen bonds. I think the idea here, more than the relatively minute differences between non-ionic and non-covalent bonds, is that ...
by Garrett Dahn 1I
Sun May 20, 2018 10:59 pm
Forum: Electronegativity
Topic: Isoelectronic [ENDORSED]
Replies: 11
Views: 542

Re: Isoelectronic [ENDORSED]

In the scenario of two elements being isoelectronic, why wouldn't the element gaining or losing electrons entirely become the other element it's isoelectronic to? Ie. Why wouldn't F- just become Ne? The feature that distinguishes elements is their atomic number, which is just the number of protons ...
by Garrett Dahn 1I
Sun May 20, 2018 10:48 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge purpose
Replies: 33
Views: 1157

Re: Formal charge purpose

If having a formal charge of 0 means that an atom is most stable, then why do atoms like chlorine tend to have a negative charge when isolated (ie Cl-)? I'm not entirely sure I'm correct here, but I think the reason we usually write Cl as Cl- doesn't have to do with formal charge so much as the fac...
by Garrett Dahn 1I
Wed May 09, 2018 9:43 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question 5 from week 5 review
Replies: 1
Views: 132

Re: Question 5 from week 5 review

Since l is 2, we know this orbital will be a d orbital (l = 0 is s, l = 1 is p, l = 2 is d, l = 3 is f) and that its energy level will be 3, so the orbital will be 3d with 5 of these orbitals (just like how you had it). This orbital can hold 10 electrons.
by Garrett Dahn 1I
Wed May 09, 2018 9:37 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Module Question 23
Replies: 2
Views: 166

Re: Module Question 23

The uncertainty in position (delta x) should be 10 meters since this value is meant to represent the spread in the position. Working out the equation and solving for delta v with 10 as delta x and 2150 kg as m, I got 2.45 x 10^-39 m/s. Did you get this too?
by Garrett Dahn 1I
Tue May 08, 2018 7:08 pm
Forum: General Science Questions
Topic: Past Midterm Question
Replies: 2
Views: 223

Past Midterm Question

Looking at past midterms, I came across this question and have been trouble figuring it out. The question is this: If the computing performance of a supercomputer is only related to the speed of the electron, would high energy photons improve performance? I'm told the answer is "no", thoug...
by Garrett Dahn 1I
Sun May 06, 2018 8:48 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions for Electron Configuartions
Replies: 5
Views: 189

Re: Exceptions for Electron Configuartions

The half-full stability creates a symmetry that is desirable for atoms such that having a half-filled orbital, like, say, Nitrogen, is more stable than having a lone valence pair. This means that the ionization energy (the energy required to remove an electron from the atom -- literally the energy t...
by Garrett Dahn 1I
Sun May 06, 2018 8:33 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Configuration of Fe
Replies: 2
Views: 94

Re: Configuration of Fe

That is the correct electron configuration, yes. That 3d comes before 4s because the n energy level of 3d (n = 3) is lower than the n energy level of 4s (n = 4), and according to the Aufbau principle, electrons will occupy lower energy levels before they occupy higher ones.
by Garrett Dahn 1I
Thu May 03, 2018 4:14 pm
Forum: Trends in The Periodic Table
Topic: lecture question 5/2
Replies: 3
Views: 95

Re: lecture question 5/2

I'd like to reference the final part of your question about contraction. Professor Lavelle called this electron contraction because the electrons are literally being contracted by the increasing positive charge of the nucleus, since as you move to the right on the periodic table, the number of proto...
by Garrett Dahn 1I
Sun Apr 29, 2018 11:33 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Aufbau Principle Diagrams [ENDORSED]
Replies: 2
Views: 111

Re: Aufbau Principle Diagrams [ENDORSED]

The spacing between orbitals decreases for the same reason that the space between energy levels (n = 1 and n = 2, for instance) decreases, and for the same reason that in a Lyman or Balmer series, the distance between spectral lines decreases. That distance decreases (I think) because of the relatio...
by Garrett Dahn 1I
Sun Apr 29, 2018 11:25 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Hund's Rule [ENDORSED]
Replies: 6
Views: 219

Re: Hund's Rule [ENDORSED]

In practice, all this means is that when you are apportioning your electrons into their respective orbitals, you will not have paired spins (↑↓) until you've first filled all of the slots in the orbital once. The whole conceit behind this is that electrons are lazy and want to occupy the lowest ener...
by Garrett Dahn 1I
Sun Apr 29, 2018 11:07 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Test 2 Q4 help [ENDORSED]
Replies: 3
Views: 194

Re: Test 2 Q4 help [ENDORSED]

I, too, was thrown off by this question, and went through about three separate convoluted attempts before arriving at the far simpler E = hv process. I think what finally convinced me that this was in fact an E = hv problem was the wording of the last two sentences: "a scientist claims that the...
by Garrett Dahn 1I
Sun Apr 22, 2018 6:36 pm
Forum: Properties of Light
Topic: Wavelength and energy in Lyman and Balmer Series
Replies: 2
Views: 110

Re: Wavelength and energy in Lyman and Balmer Series

Ah, that makes sense. So essentially the distance between the energy levels is perpetually decreasing because of the relationship between that frequency and the energy level itself.
by Garrett Dahn 1I
Sun Apr 22, 2018 6:32 pm
Forum: Photoelectric Effect
Topic: Threshold Energy [ENDORSED]
Replies: 4
Views: 124

Re: Threshold Energy [ENDORSED]

Also important to note that the energy remaining after the threshold energy is reached is expressed as kinetic energy of the electron actually being ejected, such that KE = E(photon) - E(threshold)
by Garrett Dahn 1I
Sun Apr 22, 2018 6:29 pm
Forum: Properties of Electrons
Topic: Remembering hydrogen spectral series and associated radiation
Replies: 2
Views: 127

Re: Remembering hydrogen spectral series and associated radiation

I'll agree with Jazmin here: I think it is important mostly to understand that the Lyman Series is associated with short wavelengths of the ultraviolet variety and the Balmer Series is associated with longer wavelengths of the visible light variety. It might also be helpful just to memorize that vis...
by Garrett Dahn 1I
Wed Apr 18, 2018 3:30 pm
Forum: Properties of Light
Topic: Wavelength and energy in Lyman and Balmer Series
Replies: 2
Views: 110

Wavelength and energy in Lyman and Balmer Series

In studying the spectral lines for the Lyman and Balmer series, I've noticed that the lines themselves decrease in distance from each other as the wavelength decreases. I know this has to do with discrete energy levels and the notion that the distance between energy levels decreases the further you ...
by Garrett Dahn 1I
Sat Apr 14, 2018 5:17 pm
Forum: Empirical & Molecular Formulas
Topic: Compound Order
Replies: 5
Views: 193

Re: Compound Order

When you're dealing with those four elements specifically, I think it is preferable to arrange them as CHNO. There's this principle called the Hill System which posits that when you're arranging elements in a chemical compound, carbon will come first, hydrogen will follow, then the remaining element...
by Garrett Dahn 1I
Sat Apr 14, 2018 5:07 pm
Forum: Photoelectric Effect
Topic: Higher Frequency and Kinetic Energy [ENDORSED]
Replies: 5
Views: 279

Re: Higher Frequency and Kinetic Energy [ENDORSED]

Assuming that the frequency is already high enough for an electron to be ejected, higher frequency light would emit electrons with higher kinetic energy. However, for the midterm question, you can't make this assumption (and therefore the statement is not true). I just wanted to flesh this out a li...
by Garrett Dahn 1I
Sat Apr 14, 2018 4:56 pm
Forum: Photoelectric Effect
Topic: ENERGY PER MOLE OF PHOTONS [ENDORSED]
Replies: 3
Views: 118

Re: ENERGY PER MOLE OF PHOTONS [ENDORSED]

I agree with Jade and think it definitely has to do with the idea that single photons interact with single electrons. I think multiplying by Avogadro's Number has to do with that 1-1 relationship.
by Garrett Dahn 1I
Sat Apr 14, 2018 4:51 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Definition of Avogadro's number
Replies: 3
Views: 215

Re: Definition of Avogadro's number

Not sure if this is exactly related, but because a "mole" is really just a certain number of atoms, we can't really measure moles in a lab. Instead, we use grams. I think this is significant in being sure to convert from moles to grams at the beginning of a majority of these especially int...
by Garrett Dahn 1I
Sat Apr 14, 2018 4:48 pm
Forum: Empirical & Molecular Formulas
Topic: Order of Elements in Empirical Formula [ENDORSED]
Replies: 4
Views: 656

Re: Order of Elements in Empirical Formula [ENDORSED]

Be that as it may be, no matter how the elements are arranged in a chemical formula, the actual chemical you are representing will not change. So even though CH2 is the better way to write this formula, H2C means the exact same thing. I don't think we will be expected to exactly know the order of mo...
by Garrett Dahn 1I
Sat Apr 14, 2018 4:43 pm
Forum: Balancing Chemical Reactions
Topic: Another Way to Balance
Replies: 7
Views: 236

Re: Another Way to Balance

So since high school I've just been using guess and check, or at least some variation of that, and there would always be a couple equations that would give me so much grief to check. My TA, however, recently described a different way to balance chemical equations that seems to be a little more suref...

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