Molecule Definition and 462 Threads

Hi there, I'm trying to reconstruct the ESP charges that have been determined in a paper using a Gaussian-like quantum chemistry program. While I understand the basic notion of the iterative procedures to approximate the wavefunctions etc., I'm not a chemist and so I'm having problems with...

Homework Statement 20. If the central N in the NH3 molecule did not use sp3 hybridized orbitals. What would be the expected angle in NH3? Homework Equations The Attempt at a Solution I should just consider 3 of the H: 1s^{1} bonding with the P_{x} , P_{y} , P_{z} respectively and the angle is...

Homework Statement Consider the H2 molecule. The two nuclei (protons) have spin 1/2 and can therefore be in a total spin S=0 or an S=1 state. What is the orbital angular momentum of the two-nucleon system in the lowest energy state for the two values of the total spin? Homework Equations...

Homework Statement ...Suppose an oxygen molecule (m=5.32E-26 kg) traveling at this speed (\nu_{rms}=484 m/s) bounces back and forth between opposite sides of a cubical vessel 0.10 m on a side. What is the average force the molecule exerts on one of the walls of the container? (Assume that the...

1. The average translational kinetic energy of a nitrogen molecule at temperature is _____ check picture 2. 3. The Attempt at a Solution : since nitrogen is diatomic then it has 5 degrees of freedom and therefore the average kinetic energy wouldn't be 3/2kt it would...

Homework Statement Gas is contained in an enclosure in which one of the walls is a plane of area A. The wall acts as a frictionless piston, moving with constant velocity u in the positive x-direction, thus increasing the volume V of gas enclosed. A gas molecule of mass m approaches the...

Hello, I am new in computational chemistry. I was calculating by "Moller Plesset Second Order perturbation theory -MP2-" (using GAMESS) molecular parameters of Cs3Cl2-. Among them i found two complex frequencies of vibration. My question is now, what is the physical meaning of those complex...

Why is the positive charge of the NAD+ molecule located on the nitrogen in the nicotinamide group? This nitrogen has 4 bonds attached to it, but nitrogen only has 3 holes in its valence shell, so wouldn't this make a negative charge on this nitrogen?

I am wandering whether this can happen? When a molecule shares 4 pairs of bonded electons? Say like a C2 Molecule?? maybe. Could it happen or does it happen??

Homework Statement For l=1 the angular momentum components can be represented by the matrices: \hat{L_{x}} = \hbar \left[ \begin{array}{ccc} 0 & \sqrt{\frac{1}{2}} & 0 \\ \sqrt{\frac{1}{2}} & 0 & \sqrt{\frac{1}{2}} \\ 0 & \sqrt{\frac{1}{2}} & 0 \end{array} \right] \hat{L_{y}} =...

How do you use the C_ij matrix to find the harmonic frequency (or frequencies) of a diatomic molecule, the OH (hydroxyl) radical? (I have no idea how to set it up for this.) This is from Feynmann's book on Statistical Mechanics...

Hi all. I love the fact that you have this forum! I need help with a problem of mine that has been lingering in the back of my mind for years. I would like to put it to rest. I am a backyard hands on kind a guy with regards to Physics. My background is in Mechanical Engineering but I have...

Its common knowledge that infra red radiation heats up an absorbing solid surface. That is,the em radiation energy is converted into translational KE of the particles of the solid. What happens in the case of an isolated CO2 molecules absorption? Can the EM energy be converted into increased...

Homework Statement A molecule of DNA is 2.17 micrometers long. The ends of the molecule becom singly ionized: negative on one end, positive on the other. The helical molecule acts like a spring and compresses 1.00% upon becoming charged. Determine the effective spring constant of the molecule...

Hi there, i'm trying to do molecular dynamics simulations with CO2. However, I'm running into some problems, that I don't fully understand up to know. From a naive point of view, I would describe CO2 as a linear molecule consisting of 2 C-atoms and 1 O-atom. To simulate a flexible model...

Homework Statement An oxygen molecule vibrates so that the distance between its intramolecular bonds changes from 1 Angstrom to 3 Angstrom. This change occurs 1000 times every second. If the average speed of the movement is 100 m/s, and the weight of the molecule is 10^-26 kg, how much...

Inter-atomic force in a Hydrogen molecule -- finding "spring" stiffness Homework Statement At about 2000 K the heat capacity (at constant volume =) increases to (7/2)k per molecule due to contributions from vibrational energy states. Use these observations to estimate the stiffness of the...

Homework Statement A chemical plant produces pesticide that contains a molecule potentially harmful to people if the concentration is too high. The plant flushes out the tanks containing the pesticide once a week, and the discharge flows into the river. The molecule breaks down gradually in...

Does anyone know where I can find information about using quantum mechanics on the diatomic molecule (E.g. Lectures on YouTube or just notes)? Thanks.

Hi, 1st year chem guy here...I'm missing this idea. Is it all based upon Electronegativity? I can see why HBr or HCl and other 2 atom compounds would be polar. 2 atoms with different charges or even sizes creating an un-even pull. I'm guessing H2O is polar as the 4 remaining electrons on...

Which size of the molecule is bigger? Water or oxygen? Can someone state out the size unit of these molecules And, can I find a meterial to separate this 2 matter but let one of it pass through the other? (Osmosis effect) Really appreaciate who can help out here, thx

Mechanical Energy of Amonia Molecule [SOLVED] Homework Statement The ammonia molecule has the tetrahedral structure shown in the figure (Intro 1 figure) . The three hydrogen atoms form a triangle in the xy-plane at z = 0. The nitrogen atom is the apex of the pyramid. The figure (Intro 2...

Homework Statement You place 83 moles of hydrogen gas in a balloon of volume 2.8 m3, and find the pressure to be 1.4 times atmospheric pressure. What is the typical speed of a hydrogen molecule? Homework Equations v=(sqrt)((3*Boltzmann Constant*T)/mhydrogen T=pv/nr The Attempt...

Hi there all, I have this problem which I have issues with; there's some stuff I need to do in C and any help would be much appreciated. For V(o) = 36 i need to find the ground state energy and normalised ground state function using matrix methods. I am allowed to use Matlab to find the...

Hello everyone, Quick questions. What do they mean by different polarities in anti parallel DNA strands. Are they referring to some chemical polarity or simply the fact they run in opposite directions. I'm confused with DNA replication. DNA polymerase can only synthesize DNA in 5' to 3'...

Hello Everyone! I need help on this topic. Can anyone provide me some details on how to solve the problem? Thanks..

Hello If a molecule has two specific vibrational modes (eg. symmetric and antisymmetric stretching in H2O), and they occur at different frequencies, v1 and v2, then why is the absorption band associated with a combination of these two modes labelled "v1 + v2"? My intuition is that the H2O can...

Hello I am working through a textbook here, struggling to follow a mathematical step. We are deriving the partition function Q due to pure rotation of a system containing molecules with quantum rotation energy levels: E = h2J(J+1) / 8pi2I Where J is the rotational quantum number, J = 0,1,2...

What exactly does it mean for a molecule to be in an 'activated form?' How exactly does this correspond to its energy levels? By this I mean how UDP-glucose is an activated form of glucose, ATP is an activated form of orthophosphate, and acetyl CoA is an activated form of acetate. (I pull...

1. Homework Statement Consider a gas-phase N2 molecule. It's RMS speed is given by Vrms = (3kT/m)^(1/2) What speed would the gas molecule have if it had the same energy as a photon of the following wavelengths of IR, visible, UV and X-Ray electromagnetic radiation? lambda =...

Homework Statement Consider a gas-phase N2 molecule. It's RMS speed is given by Vrms = (3kT/m)^(1/2) What speed would the gas molecule have if it had the same energy as a photon of the following wavelengths of IR, visible, UV and X-Ray electromagnetic radiation? lambda = 1.000E4nm...

I know that placing a paramagnetic molecule inside a magnetic field will induce a magnetic force on the molecule from the unpaired electrons, but what will the effect be on the physical properties on the molecule (of any?) Specifically will the size of the molecule be changed? My understanding...

I know that placing a paramagnetic molecule inside a magnetic field will induce a magnetic force on the molecule from the unpaired electrons, but what will the effect be on the physical properties on the molecule (of any?) Specifically will the size of the molecule be changed? My understanding...

Homework Statement Which of the following are true statements about the above molecule ? a) The bond between carbon and nitrogen should be the strongest bond in the molecule b) The C-C bond should be the strongest bond in the molecule c) The C=O bond is more polar than the C-C...

Homework Statement Calculate Velocity of an oxygen molecule at height, where the temperature is -50C. O2 molecule: 5.4x10^-26 kg Homework Equations 1/2mC^2=3/2kT The Attempt at a Solution => 1/2 (5.4x10^-26) c^2 = 3/2 (1.38x10^-23) x -(50) => c2= 1.035x10^-21 =>c=3.21x10^-11 m/s...

Homework Statement The harmonic oscillator problem may be used to describe the vibrations of molecules. For example, the hydrogen molecule H2 is found to have equally spaced vibrational energy levels separated by 8.7 × 10-20 J. What value of the force constant of the spring would be needed to...

Problem: What is the ratio of the probability of finding a molecule moving with the average speed to the probability of finding a molecule moving with three times the average speed? So I know I need to use the Maxwell Speed Distribution for this: D(v) dv = (m/(2(pi)(k)(T)))^(3/2) *...

Homework Statement Molecules of carbon monoxide are permanent electric dipoles due to unequal sharing of electrons between the carbon and oxygen atoms. The figure shows the distance and charges. Suppose a carbon monoxide molecule with a horizontal axis is in a vertical electric field of...

The researchers focused on a single molecule of pentacene, which is commonly used in solar cells. The rectangular-shaped organic molecule is made up of 22 carbon atoms and 14 hydrogen atoms. In the image above the hexagonal shapes of the five carbon rings are clear and even the positions of...

awesome! i guess it won't be long now before people will be able to do this with their iPhones: http://www.dailymail.co.uk/sciencetech/article-1209726/Single-molecule-million-times-smaller-grain-sand-pictured-time.html

a water monomer has HOH angle of 104.5 and OH length of 0.98 , partial charges are +0.4 on H and -0.8 on O. The reported electric dipole moment for this monomer is 1.86D. I tried to calculate it and got 2.3 D. The way I do it is by multiplying the distance between the center of the H-H and the...

is there any contradiction between the two?

The speed of sound in the air is constant no matter what its frequency f is. Fine. But what is the speed of an air molecule which transmits that sound of frequency f? The higher the frequency, the higher the speed of the molecule, right? What is the equation which gives this velocity? (and a...

Homework Statement Heat is added until the rms speed of a helium atom has increased 50%. Find new pressure. (Not all parameters given.) Homework Equations rms = (3kT/m)1/2 mass of molecule = mass of mole/NA Then, mass of helium molecule is 6.6x10-26kg The Attempt at a Solution...

Can someone give me a clear picture of it's physical meaning? What does a molecule having dipole moment signify? All the explanations I've seen are very hazy.

Homework Statement Compute the rms speed of a nitrogen molecule of 35.0 celcius. Homework Equations V(rms) = sqrt((3RT)/M) The Attempt at a Solution I plugged in 8.31 for R and 308 K for T and 14.0 g/mol for M. I arrived at a solution of 23.4 m/s but this answer came back as...

Homework Statement Show that the frequency of oscillation, v, of a molecule is related to the form of the inter - atomic potential V(r) about the equilibrium separation, r =ro by the expression, v = (1/2pi).sqrt([d2V/dr2r=ro/(m)]) where m is the reduced mass Homework Equations None given...

How do you calculate the resonant frequency required to shatter a calcium or magnesium molecule?

Homework Statement a) Given the IUPAC name to the chemical formulas: {\left[ {Ni{{\left( {N{H_3}} \right)}_6}} \right]^{2 + }} \left[ {CrC{l_3}{{\left( {N{H_3}} \right)}_3}} \right] {\left[ {Co{{\left( {N{O_2}} \right)}_6}} \right]^{3 - }} b) Give the metal oxidation state...

hi guys, i need some help with the following questions relating to cross sectional area. thanks in advance! 1) when n-hexatriacontanoic acid, CH3(CH2)34COOH was placed in water, a complete monomolecular film was formed. if the length of a carbon-carbon single bond in the chain is 1.54...