mississippichem

Yes, they are common practice in Quantum Chemistry circles. I'm not sure if they are so common in physics circles. They are nice because it does ensure the anti-symmetry and it can give you a simple [math] \Psi = \phi _{1} \phi _{2} \phi _{3}... [/math] in some cases which is well appreciated. This of course only holds if you neglect the non-adiabtic coupling terms and use the much nicer [math] \mathcal{H} ^{0} [/math] instead of the full Hamiltonian. I think it also allows you to treat the electron-electron repulsion function as being pair-wise additive. Which lends itself to separation of variables.

vibration, rotation, and translation.

The characteristics of the molecular orbitals come directly from the atomic orbitals that formed them. We use something called Slater determinants [read some about matricies] to calculate these molecular orbitals from their constituent atomic orbitals. This is called LCAO, linear combination of atomic orbitals. The behavior sometimes depends on whether or not we treat the atomic orbitals as one electron "spin-orbitals" or two electron "Gaussian-orbitals". As far as the molecular electrons affecting the non-bonding electrons: that is a very complex topic that I will hopefully learn more about in grad school. I do know of one treatment called dynamic pair correlation that I know roughly how to work with; it involves perturbation theory. Qualitatively, remember that fermions do not like to share space and neither do like charges. Also remember that the entire set of orbitals for a species exists in a dynamic set. Changing the energy level of one electron will produce effects on all the other orbitals and the geometry of the molecule as a whole (see Ligand Field Theory). Also, in some rotational conformations, there is a degree of "mixing" between orbitals. So sometimes, when observing a radiative transition we can't resolve which orbital the photon came from; or we might not even observe the transition at all if the mixing is just right.

You British people know how to drink. I got a couple of English friends here in the states who are always the life of the party.

I've always been a bit fascinated by hypothetical silicon based life forms. My chemistry background reminds me that they are not likely to exist anywhere because silicon has trouble forming catenated double bonds; but that doesn't keep me from entertaining the idea. What's interesting to me is that any silicon based life from would necessarily have to have a water free biochemistry. Someone wrote some science fiction on the topic but I can't seem to recall at the moment. If you can find it, I'm sure it is quite interesting/entertaining.

Covalent bonds behave very differently from the conduction band in bulk metals. Electrons in most molecular orbitals cannot communicate. Meaning that an electron in said orbital cannot be conducted through the bond to another orbital. The reason for this is quite mathy, but in quantum chemical treatments we have these things called "cusps". Places where the probability of finding an electron drops to zero or very near zero. There are nuclear and electron-electron cusps. They can be seen to arise from symmetry properties or directly out of the type of Hamiltonian we use to operate on our Schroedinger equation. The wavefunction describing the behavior of the electrons, [math] \Psi [/math], is separate from the waveunction describing the vibrational motion, [math] \chi [/math]. There are cases where the vibrational and electronic wavefunctions are coupled [not mathematically separable] but I would not say that the "springlike" motion of the bonds is a result of electronic oscillations directly. The "spring bond" treatment I introduced to you earlier is only good for predicting the absorption frequencies of the bonds with respect to spectroscopy and such. In reality, the non-electronic degrees of freedom in a molecule are also quantized and are analyzed as wave equations.

It's not, the half-life of [ce] ^{14}C [/ce] isn't long enough. But radiometric dating is valid in general. IIRC, radio potassium-argon dating works for time scales of that magnitude.

Alright good, so what parts are you struggling with? Also, think out loud a bit so I can see your reasoning. We're not supposed to give answers [especially since much of this is multiple guess choice ] but I can more than likely steer you in the right direction.

Maybe, but it is very hard to prove that no atoms/molecules are in a given space.

Your link is password protected. I'm glad to help but unfortunately can't read the assignment.

I agree, before we had cruise missiles and AK-47s, we would just beat each other over the head with rocks or sticks. Chimps throw rocks at rival troop members, they even steal the babies and rape the women. They have no religious or technological motivation, just good ole fashion territory/food/mating rights battles. We are animals, and animals just tend to fight. By the way, whether or not religion causes wars or not is completely irrelevant to whether or not a god or gods exist. If God does exist, then he surely causes wars; see the entire Old Testament. If god doesn't exist, then silly people will still fight over something. "Hey, I don't like the way you put butter on both sides of your toast, it offends me and I want to kill you and your stupid culture." I'm sure that in that universe we would have a thread vigorously debating the merits and cons of "double-sided-toastism".

I agree with Spyman, and therefore Lemur. I think it's best to keep the bad language to a minimum here. I've got a foul mouth, so do you ydoaPs, . I can't help it, my dad was a sailor. But I think it is quite easy to keep it to a minimum when typing. I can yell, **** all I want at my computer screen as I read about some half-wit's quack theory; but there's just no reason to type it (except for on IRC). We do have a lot of children around here looking for help. Even though I don't find course language offensive, I'm sure many of them do and the same goes for their parents. Plus, we're all supposed to be somewhat educated here right? Typing vulgar language in your post shows your lack of descriptive vocabulary, and or math skills in this setting.

Metals bonded together in a crystal don't have the same electronic behavior as ionic solids or covalent solids. The metal atoms all share share electrons in the conduction band. This isn't something I'm very familiar with as I'm not a solid state chemist. If memory serves, Klaynos knows about solid state physics. See if you can find him.

As you move to the right in the p-block, (B, C, N, O, F, Ne...), the every element has one more electron in that p-orbital than the last. Boron has 1, Carbon has 2...so the halogens have 5 electrons in their valence p-orbitals, and p-orbitals can only hold 6 electrons. As we go along that period [row] the nucleus is getting larger so the effective coulombic attraction on those electrons is getting larger, hence the tighter atomic radii. Wikipedia atomic radii; they have a good chart.

Aliens killed Osama bin Laden! I saw it on the history channel so it has to be true right!?

Even though your debt to assets ratio could be too high for your taste (depends on how much credit card debt you have). It is a good time to get a home equity loan considering interest rates are in the tank. Just be sure to do the math and make sure you are getting a deal here. Also, keep in mind, that if you don't make good on the payments, you've just made your home collateral. I wouldn't recommend getting a car loan at your age and you're uncertain citizenship status. At your monthly income you might be able to cash flow a car though. Buy a beater until you pay down that debt . Keep in mind I'm no CPF or CPA (though I'm very interested in finance and a little bit knowledgeable) so consult a professional if you really want good advice. Just make sure the guy isn't commission payed with reference to selling you a home equity loan. If he is, then you'll walk out with a home equity loan regardless of whether you need one or not. The first question to ask an investment or financial advisor is: how are you compensated? I, personally wouldn't feel comfortable taking out a home equity loan if my current liabilities exceeded one year's income (except for the house). That's just a general rule of thumb though, I tend to play the conservative side on debt management. Keep in mind that you can't default on the student loan debt if it is subsidized! You will pay them that in one way or another.

If you gain an electron, your charge is "reduced" to a more negative value.

Correct. A molecule can be both hydrophobic and lipophobic. But if a molecule is lipochilic it will definitely be quite hydrophobic. Good examples include the highly fluorinated organic compounds. Many of them are very lipophobic and very hydrophobic, but they are fluorophilic, meaning they have high solubility in and affinity for other highly fluorinated compounds. I'm a bit perplexed by this thread though. How are we proposing to make keratins more lipophilic? It most definitely makes a difference. Let's also remember that lipohilic and hydrophilic are not absolutes. Every compound has some solubility in every solvent, though it may be extremely tiny. What we need is a LogP value for a specific keratin. Given by comparing comparing differential solubility in two different solvents, usually water and octanol: [math] logP = log \left ( \frac {[X]_{octanol}}{[X]_{water}} \right ) [/math] If someone wants to find an experimental logP for a specific keratin, I'll use my handy ChemDraw comp. package to calculate a parameterized logP for the proposed more lipophilic analogue. Then we wounldn't be just wildly speculating but would have somewhat of a quantitative link to reality.

Yeah, but he seems to be missing his dorsal spines. Even if it's female, the dorsal spines should be larger than pictured. I have a male with very large dorsal spines even though he is still somewhat juvenile. This looks like an adult.

Alright let me help you understand oxidation: Oxidation is defined as the loss of electrons, reduction is the opposite and is the gain of electrons. Yes, you can have oxidation without oxygen, this is a terminology inconvenience. Usually, adding oxygen to a molecule ends up oxidizing that molecule though. Every time a molecule oxidizes another molecule, it becomes reduced by the molecule it oxidized. So if A oxidizes B, then you can say that B has reduced A. Most of the time, elemental [plain atoms] metals tend to reduce non-metals. So lets look at an example with sodium, a very strong reducing agent. [ce] 2Na + 2H_{2}O -> 2NaOH + H_{2} [/ce] This is the full reaction equation for elemental sodium reacting with water [i chose this because it an easily analyzed and fundamentally 2 electron process. Multi-electron processes can get complicated]. So here, sodium metal is oxidized by water, and water is reduced by sodium metal. Let's break these into "half-reactions" for clarity. *([ce] e^{-} [/ce]stands for an electron) For the oxidation: [ce] 2Na^{0} -> 2Na^{+} + 2e^{-} [/ce] For the reduction: [ce] 2H_{2}O + 2e^{-} -> 2OH^{-} + H_2 [/ce] So now we can see how sodium is losing an electron, while water is gaining one. You can recombine these two half reactions to regain your original equation. Don't think of metals as having an electron abundance, think of them as being willing givers of electrons. In a bulk material, any given metal atom is actually electron deficient. All the metal atoms in the bulk share electrons in what's called a conduction band. Metals are metals because their effective nuclear charge, [math] Z^{*} [/math] (nuclear charge once you subtract out all the inner electron shielding) on the outer electrons is low; yielding a very low ionization energy. Thermodynamically speaking, it requires little energy to remove a mole of electrons from a mole of metal atoms, when compared to non-metals.

You can think of it that way, but I'm not sure if you'll see any advantages by doing so. You can group compounds into families but it is only arbitrarily useful. You can think of ethane, propane, butane, pentane... as polymers of methane, but it really doesn't make much difference. I can think of this molecule as a carboxylic acid derivative of benzene or conversely a phenyl-substituted methanoic acid. The reaction to get to this molecule would be the same either way, regardless of which molecule I call the substrate. Personally, I usually call the larger fragment the substrate. As far as naming goes, there are IUPAC (international union of pure and applied chemistry) conventions that are supposed to be used for that. Most people follow them, though some common molecules have slang terms like water; which is technically dihydrido oxygen by inorganic naming convention.

In my opinion the reason for having a war on terror is not to spread democracy. It is to stop insane nut-bags [whatever their motivation is, religious or not] from committing atrocious actions against civilians. Most of the time that is a tall order and requires said nut-bags be killed. I don't think we need an ideological motivation. In fact ideological motivated acts of war are the things we are trying to stop. Our enemies celebrating as we die is no more wrong or surprising than us celebrating when our enemies die. And it is guaranteed that as long as we don't act decisively and intensely the crazies will continue to be an annoyance and or a threat in the future. We have no motivation other than wanting people like Bin Laden to cut it out with the anti-western nonsense. If you think my view is ethnocentric, then you would be right. I think in the interest of the culture in which I live as does everyone else who values self preservation.

Denying him the proper burial deals a major blow to the morale of Al Queada. I personally didn't want him to be tried on international TV so that he can spout his anti-western propaganda and make a new generation of Al Quaeda recruits. If he hated the way we operate the western world so badly, then we won't allow him to enjoy the hospitality of our western court system. He lived by middle-east third world style justice, so that's what we gave him. A one way ticket to the bottom of the Persian gulf. I bet it was an assassination attempt, and I'm glad it was. This is what we should have done all along. Why start a war and kill thousands of civilians when you can just pick off the major baddies one by one. Wars are won by tech, intel, economics, and psychology these days.

How much equity do you have in your house?