Molecular Definition and 545 Threads

I know that the sigma 2p bonding orbital could be less/higher in energy than the pi 2p bonding (based on if it is C2,N2,B2 etc), but Why is the sigma 2p antibonding orbital always higher in energy than the pi 2p antibonding one?

I was attempting this question where I had to say which, out of graphite, diamond and sodium chloride represent a giant molecular structure? The answer is only the first two. Why is the latter excluded?

Hi, I have finished an experiment about vibronic transitions for the N_2 molecule and I'd like to compare my results ( vibrational frequencies and dissociation energies of the electronic states interested in the N_2 second positive and N+_2 first negative band systems ) with the accepted...

Hey guys, I'm an engineering PhD student, and I'm doing some work with laser-induced fluorescence. At the moment, I'm trying to understand some notation about the excited states of nitrogen dioxide. One of the papers I'm looking at, V.M. Donnelly, et al. J. Chem. Phys. 71, 659 (1979), is saying...

I'm not too sure if this is the correct subforum to post this question in. Anyways I have taken Biochemistry only. I signed up to take molecular biology and I'm wondering if that is a bad idea with no previous coursework taken in genetics (the only biology college course I have taken is...

I have worked in the field of wildlife biology for years and have recently switched professions to teaching. One of my biggest concerns with the current biology curriculum is that it seems way too obsessed with it's molecular aspects. I think this over-focus can be extremely harmful to the...

Homework Statement http://img191.imageshack.us/img191/3277/59596364.jpg The Attempt at a Solution I used the Maxwell-Boltzmann distribution equation: KE_{avg}=\frac{1}{2}mv^2 = \frac{3}{2}k T \implies v = \sqrt{\frac{3kT}{m}} The most probable velocity for argon would be: v =...

hey, i want to understand how does the molecules of a rope or cable generate tension when force is applied at both ends. consider a block of mass m hanging from a ceiling with the help of a string. please explain what's goin on at the molecular level in a rope when forces are applied at both ends.

Could anyone help me in solving this following problem. From the given data, i could calculate the dipole moments of all the disubstituted chlorobenzenes(o-, p- and m- isomers)..but i couldn't calculate the following...I would be thankful if anyone comes up with a needful explanation...thanks...

What type of bond is Sulfuric Acid (H2SO4(aq))? People tell me its ionic because the acid is made up of a polyatomic ion. However, many sources online say that the acid is polar. I can't seem to figure out which bond it is.

Hello, some time ago I found a website dedicated to neuroscience. It deals with neurons, receptors, synapses etc on molecular level. The site is free and has a lot of information, including pictures, diagrammes etc. I think it is a project of some professor who wants that information be...

Homework Statement As the title would lead you to believe I have to classify each solid as a covalent, ionic, metallic, or molecular solid. These are the given solids Calcium Fluoride Rhombic Sulfur Frozen Ethanol Pure Calcium Homework Equations n / a The Attempt at a...

Homework Statement Determine the electron geometry and molecular geometry or the underlined carbon in CH3CN. A) tetrahedral/tetrahedral B) linear/trigonal planar C) trigonal planar/bent D)linear/linear E)trigonal planar/trigonal planar I'm not really sure how to structure this...

My question is as follows. When (qualitatively at least) constructing molecular orbitals for a given molecule, a few "rules" are used to construct them. I'm wondering why the "rules" exist at all. For example, it is given that orbitals must have "similar energies" (however one quantifies...

Homework Statement I need to calculate the mas of a molecule of an unknown gas in the atmosphere from the values: T = 500 K mass of the planet = 1.5 × 1024 kg radius is 3.0 × 106 m universal constant of gravitation, G = 6.67 × 10^−11 N m^2 kg^−2 P at ground level = 2.0 × 10^7 Pa P...

Homework Statement Okay I've been stuck with this problem for two whole freaking days now, and it's really gotten on my nerves and I've given up completely on it because I'm positive I didn't pick up the concept for this even though I studied it from about 4 different books! It's just a simple...

The problem A bubble of kryptopn (Kr) gas is formed underwater. The bubble has a volume of 2.14x10-6m3 and contains 1.70x1020 krypton molecules each of mass 1.39x10-25kg. The pressure of the gas inside the bubble is 300kPa. Calculate the relative molecular mass.The attempt at a solution When...

I am not a chemist. I have a molecular structure question. Is it possible to bind two positively charged molecules together by having two electrons bounce up and down in the space between them? M1+ e e M2+ imagine the e, electrons oscillating up and down. Either in sync and 180...

Hey, I've simulated a solid metal cluster of gold fcc100 And a surface Platinum in fcc111 using a classical mechanical approach. Do you think i could get the surface free energies(the ones to use in determining the Wulff shape) from periodic boundary conditions and if so how? I am really...

Hello,world 1-"the intermolecular attractive forces between gas particles are very weak due to the large intermolecular distances separating them" Is that true? this is wriiten in my textbook and it is confusing me because I've always thought of it in a different way ,I thought the...

I'm watching a fascinating video about DNA replication: Can someone explain briefly what the mechanism of action (and locomotion) is for all these little machines? Is it simply electric potential (due to ionization?) ? Thanks

Hi everyone I'm currently studying the MO theory and ran into some trouble understanding orbital energy levels. As I have previously read, σ bonds are stronger than ∏ bonds, therefore are lower in orbital energy. However, from the MO theory, the σ2p orbital is actually higher in energy than...

[b]1. A 0.0097561 g quantity of an unknown gas occupies 0.2 L at 500 K and 2 atm. What is the Molecular Weight (MW) of the gas ? [b]2. PV = nRT [b]3. mw=0.0097561*0.082*500/2*0.2 mw=1

It looks like the bio-hacker movement are a step closer to their dream as one man tries to make a http://www.mlo-online.com/features/201112/tips-from-the-clinical-experts/the-quest-for-the-500-dollar-home-molecular-biology-laboratory.aspx. I've always been in two minds about DIY biology, I've...

Homework Statement What is the difference between molecular mass and molar mass? Are they related? Homework Equations moles = total mass/ mass/mole The Attempt at a Solution I can't find any explanation in my lecture notes. I think that: molecular mass = mass of one molecule...

I am a junior in high school I am at a total lost to what college I should apply to and what I should major in. I know that I want to work on molecular assemblers later in life, but I don't know what school will be best for me. Can anyone please help me find out which school I should apply to...

From the viewpoint of the continuity principle, we know that the stream of water is fatter near the mouth of the faucet and skinner lower down. The question is how single molecules understand when/how they should deviate from their perpendicular free fall to a deviated one ?

Is the molecular kinetic energy associated with an increase of heat equally distributed to molecular vibrational, rotational, and translational energies? What is then the exact link to Brownian motion?

Hello, So, I am reading this theory, and I come across this sentence explaining to me that gas particles of different mass have the same average kinetic energy at a particular temperature. Is this somehow due to momentum? Each particle is given a certain energy which will cause them to move...

Well not literally The Maxwell's Demon... If a one-way reed valve can be brought down to size of only a few molecules, don't you think it could allow passage of a gas molecule across a barrier in one direction only? How I think it could work: -The small size (molecular) of the valve is...

1. Homework Statement I'm trying to perform a molecular orbital analysis of a tungsten hydride complex, (WH6) and I haven't been able to find an intuitive or basic definition for a "d0 complex". Every time I read an article about a d0 complex they tangentially mention them and then jump into...

Is there sth like rydberg formula for Molecular ionization?

The molal freezing point depression constant of benzene is 5.07 K kg/mol. A .45% solution of monoclinic sulfur in benzene freezes .088K below the freezing point of pure benzene. Find the molecular formula of sulfur in benzene. Can someone tell me if the answer is S2 ? I guess I'm not...

Hi all Another question (sorry) Water vapour in the air will phase shift back to liquid when it reaches its Dew Point temp (Partial Pressure = the Saturated Vapour Pressure), OK I have this. For this phase shift I assume that there are Condensation Nuclei and these nuclei are at a lower...

Hello, This is a matter I have been having some difficulties with for the past few days. My question: How is it that I would go about distinguishing molecular compounds in regards to their capacity to ionize and yield hydrogen ions when dissolved into distilled water? For example, if...

Hello, This question is a theory question: I have calculated the moles of molecular iodine in a problem (I2) and the next question asks to calculate the moles of atomic iodine. Do I just multiply the number I have by two (as iodine is a diatomic molecule) or is it a "trick" question and the...

Alright, below are screen captures of some work that I'm tackling. They show my attempts and answers at the problems. I would like to know whether I'm correct or wrong and how to correct the mistakes. The one I need most help with is, the one where you're given density and asked to find...

MFA \hat{A}\hat{B}\approx \hat{A}\langle\hat{B}\rangle+\hat{B}\langle\hat{A}\rangle-\langle\hat{A}\rangle\langle\hat{B}\rangle What this mean physically? What we neglect here? If I calculate Neel temperature using this method T_N^{MFA} and using RPA method T_N^{RPA} is there some relation...

Hi I have read this and to put it mildly I am confused, so maybe someone can clear this up. The dew point is defined as the point/temperature at which the Partial Pressure of the water vapour within the air packet equals the Saturated Vapour Pressure. I understand that the dew point is a...

Homework Statement A student allowed a 0.500 gram sample of styrene to react with an excess of bromine.* An unknown product with a mass of 1.27 grams was obtained.**The student repeated the experiment several times and always obtained the same result.**What is the likely molecular formula of...

Hi, i am self studying quantum mechanics. I completed reading of "Quantum Physics_Eisberg, Resnick" and "Introduction to Quantum Mechanics - D. Griffiths". I want to study further on Atomic and Molecular quantum mechanics. Can anyone suggest me textbook on those topics? Thanks in advance.

complete combustion of 1.1g of a compound of C,H and O gives 2.2g of CO2 and 0.9g of H2O. The compound has a relative molar mass close to 130. Find the molecular formula and true molar mass? dont even no where to begin

Molecular "work" in an Adiabatic process ? I have studied Adiabatic cooling in connection with a rising parcel of air. I’m confused. I understand that temperature is a macroscopic principle (not a Microscopic); molecules do not have a temperature, only velocity and Kinetic energy. I have read...

What technological challenges stand in the way of making molecular assemblers? I mean, what exactly would it entail to generate some sort of nanotechnology that could assemble, from scratch, a car or something? I've heard something about the "fat fingers" and "sticky fingers" problem and...

I would like to have a setup/software to geometrically simulate or represent the given molecule. For example I will input ; 2 hydrogen + 1 oxygen and it will output h2o and draw it's molecular shape. Also it would be much better if the software could give all the possible combinations of the...

If you increase mass with speed does the forces that hold molecules’ together increase in per portion ? If not do the molecules’ fall apart with speed ? If the forces increase in per portion Why does the energy released from the muluation of those forces decrease with speed.

Confusion with molecular geometry [carbon tetrachloride] I'm trying to understand the molecular geometry of four different compounds: CCl_{4} ,CHCl_{3} ,CH_{2}Cl_{2} ,CH_{3}Cl Please tell me whether my thinking is right or not[conceptually]. If it's wrong kindly correct me. for...

hi i am currently dealing with this problem here: i have some water and want to heat it up with microwaves. how do I determine the change in temperature of the water when i just know the characteristic features of the radiation? is there an equation for it? of course this process is not...

What would be a rough estimate of the computational complexity to simulate an embryo in a full-atom scale from the instant of conception to the death of the aging adult? Its a purely theoretical question and I know that its something like daydreaming for the current technology, but I would...

Iam really interested in molecular biology and microbial genetics, did masters in microbiology and want to get into doctoral program and do serious research in my interesting field. Is it not the good reason to get into phd.