CHEMISTRY COMMUNITY

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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 ...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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 ...

Garrett Dahn 1I

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 ...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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.

Garrett Dahn 1I

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?

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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.

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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.

Garrett Dahn 1I

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)

Garrett Dahn 1I

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...

Garrett Dahn 1I

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 ...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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.

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

Garrett Dahn 1I

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...

CHEMISTRY COMMUNITY

Search found 28 matches

Re: dipole moments

Re: Ligands

Re: Acids/Bases and Lewis Acids/Bases

Re: Polar VS Nonpolar shapes

Re: Formal Charge Exponent

Re: Bond Strength/Bond Type

Re: Hydrogen bonds vs. dipole-dipole bonds

Re: Isoelectronic [ENDORSED]

Re: Formal charge purpose

Re: Question 5 from week 5 review

Re: Module Question 23

Past Midterm Question

Re: Exceptions for Electron Configuartions

Re: Configuration of Fe

Re: lecture question 5/2

Re: Aufbau Principle Diagrams [ENDORSED]

Re: Hund's Rule [ENDORSED]

Re: Test 2 Q4 help [ENDORSED]

Re: Wavelength and energy in Lyman and Balmer Series

Re: Threshold Energy [ENDORSED]

Re: Remembering hydrogen spectral series and associated radiation

Wavelength and energy in Lyman and Balmer Series

Re: Compound Order

Re: Higher Frequency and Kinetic Energy [ENDORSED]

Re: ENERGY PER MOLE OF PHOTONS [ENDORSED]

Re: Definition of Avogadro's number

Re: Order of Elements in Empirical Formula [ENDORSED]

Re: Another Way to Balance