Molecular Definition and 583 Threads

Does anyone know of a good code-oriented book on molecular electronic structure theory? I've been looking for a good modern book that teaches how to write SCF code to solve simple cases of the kind of problem that standard quantum chemistry packages (e.g. Gaussian, Orca) are used for without...

A compound contains boron (40.3%), nitrogen (52.2%), and hydrogen (7.5%) - by mass. If 6.32g of this compound if dissolved in 100g of benzene, the solution freezes at 1.30 celcius. If the cryoscopic constant is 5.12 and freezing pt of benzene is 5.48, what is the molecular weight of compound...

Molecular Vibration... I'm not sure if this is a Chemistry question or a Physics question. Please take time to correct me if I have posted in the wrong area. How do you find the frequency which a certain molecule vibrates? Like Melanin, or Serotonin, or Insulin. My brother and I are...

Homework Statement What is the electron pair geometry of the following? SCN− BeCl2 O3 The Attempt at a Solution SCN− Linear BeCl2 Linear O3 Trigonal Planar Homework Statement Would the following structures be polar or nonpolar? (Not applicable if the structure is an...

Homework Statement Number 17: http://i.minus.com/jbqSc694thPeBA.jpg Homework Equations I'm not even sure where to start. The Attempt at a Solution I know that tetrahedral shapes are non-polar if all of the attached elements are the same (e.g. CH4 or CCl4). I know all the answer...

Hello, a newbie here. I need to understand the relationship between MO and Energy Bands. Although i have searched and researched about this topic in Google, but i am yet to understand this part clearly. It is said that Energy Bands occur as the number of MO increase due to the various...

Homework Statement An unknown organic compound was analyzed in a carbon-hydrogen analyzer. The combustion of a sample of the compound produced 35.2 g of carbon dioxide and 18.0 g of water. The molar mass of the compound was found to be 116.28 g/mol. Determine the molecular formula of the...

Hi forums. I have what I think is a simple question but I'm making myself confused. I'm trying to work out the relationship between energy density ( u = energy per unit volume ) and temperature in a multi-species ideal gas (no molecules just different mass ions). The simplest example of...

I am looking for a book which describes viscosity on a molecular level. The problem is that I don't have enough experience to make a wise selection. If anyone has some good pointers please share.

Why the ground state HOMO level of a molecule with two opposite-spin electrons, is singlet while we know that a level with two opposite-spin electrons may be singlet(s=0,m=0) or triplet(s=1,m=0)?

Homework Statement What is the molecular flux of argon gas, molar mass 18 g/mol, with density 0.73 kg/m3 and temperature 300 K? Answer: 3.6×10^27 collisions/m^2s Homework Equations I actually have no idea The Attempt at a Solution I can't find any reference to molecular flux in my...

1. Homework Statement A volume is divided into two equal parts by a partition. The left volume has N atoms. The atoms have a mass m. A hole of area A is made in the partition at time t=0 A)Develop an expression for the number of white atoms on each side of the partition at time t...

Molecular flux--thermodynamic kinetics Homework Statement A volume is divided into two equal parts by a partition. The left volume has N atoms. The atoms have a mass m. A hole of area A is made in the partition at time t=0 A)Develop an expression for the number of white atoms on each...

It's probably a stupid question but is it possible to attach a long proline chain - 8 or more residues - at the C terminal of a protein and have it connect to another protein and not affect folding? It's for a project and it's not actually necessary but I have to make a protein that binds to an...

Homework Statement Find the diameter of one atom of argon given that Dp = 2 where D is diffusion and p is pressure. The Attempt at a Solution molar mass of argon is 40g/mol using that for one atom can find mass in kgs. but that's its! im not given V, T or p. can put V in terms...

Homework Statement Consider two gases, A and B, in containers of equal volume. Both have the same temperature and pressure. Mass of A = 0.34 g and Mass of B = 0.48 g True or False: (justify your answer) a. The number of molecules of A is equal to the number of molecules of B. b. The molar...

Hello, Is it true that according to molecular orbital theory valence electrons in molecules are not assigned to individual atoms? Does this mean that even lone pairs are not assigned to inidividual atoms in a molecule , but rather assigned to a specified area across the molecule? Thanks!

Dear all I have a case. I have two tanks, one is filled with Helium gas and monomethylhydrazine(MMH) and another tank with Helium gas and Dinitrogentetraoxide(MON). Both tanks are at 47degC so they are in gaseous form. I want to know what will be the Molecular Mass of the gas. The...

Homework Statement A deuteron, , is the nucleus of a hydrogen isotope and consists of one proton and one neutron. The plasma of deuterons in a nuclear fusion reactor must be heated to about 3.01×108 . What is the rms speed of the deuterons? What would the temperature of the plasma be if the...

Hi All, I use commercial quantum dot from evident tech, and from the datasheet I can know its molecular weight (Mw), my question is, is this Mw also includes the organic ligand or only consider its core? what is the normal case? thanks, Yuliar

Hi all, I am currently a junior in chemical engineering and want to go to graduate school for it. I am extremely interested in the materials side of renewable energy. To make a long story short, I don't enjoy being in the lab much but really do enjoy thinking about it, researching, and...

In molecular orbital theory, only the electrons are considered and from that we draw conclusions about molecular shape and such. I was thinking just now, what about the nuclei? If we apply QM to the nuclei as well, wouldn't that mean that we can't know where the atoms are? or is the...

Author: Mark Tuckerman Title: Statistical Mechanics: Theory and Molecular Simulation Amazon Link: https://www.amazon.com/dp/0198525265/?tag=pfamazon01-20

Author: Donald McQuarrie, John Simon Title: Physical Chemistry: A Molecular Approach Amazon Link: https://www.amazon.com/dp/0935702997/?tag=pfamazon01-20

Hi all, I'm relatively new to the forum, but excited to be a part of a community discussing physics, as I lack company to really discuss my research at my place of work (university), as I am a physicist working solely amongst chemical engineers. I am using a UV-Vis spectrometer, with the...

Hi, I am looking for electronic excitation levels of molecular hydrogen like attached table. but there are only a few electronic states, i need near-threshold energy levels. where can i find all levels? thanks for attention http://imgim.com/5648inciz1637947.jpg

Author: Bruce Alberts Title: Molecular Biology of the Cell Amazon Link: https://www.amazon.com/dp/0815341059/?tag=pfamazon01-20 Prerequisities: Contents:

Can electromagnetically induced transparency, be effected on a single atom within a molecule? Thanks, Jake

Hi everyone, Right now I'm pursuing a BS in molecular biology and I decided I'd like to switch to a Bs Ed. in biology and teach high school biology. I'm 49 credits in so far just looking for some advice, part of me wants to finish the Bs degree and then get certified K-12 at the graduate...

I am working my way through Ian Fleming's 'Molecular Orbtials and Organic Chemical Reactions' and I am having trouble with one of the exercise questions. (Ch2 Q1) It reads: Given that two pi bonds conjugated together have a lower energy than two separate pi bonds and a C-H bond conjugated with...

Homework Statement Gas is allowed to expand freely when the force of a piston is removed. In terms of the molecular model of an ideal gas, explain why the temperature decreases when it expands. Homework Equations Molecular model of an ideal gas The Attempt at a Solution When the...

Hey, I'm not sure if this should be in the chemistry or physics section,. Hopefully it is in the right place. I have a question about molecular collisions: specifically, what actually happens when two molecules "collide". Perhaps a better question is: "what constitutes a molecular collision?"...

A book said that a liquid made up of non-polar molecules shows no deflection when a charged rod is placed near the liquid But if we place the charged object near an insulator,the insulator would be induced and therefore,they will stick together.(dont know I am correct Another question: A...

The S molecule of SO2 forms a double bond with one O and dative covalent bond with another O Meanwhile,XeO4 is a molecule which Xe forms a double bond with each O I have a question here Why doesn't that S forms 2 double bonds with O to extend its octet structure? Similarly,why doesn't that...

Homework Statement MgSO4*xH20 mass of hydrated comlex (g) - 6.32 mass of anhydrous complex (g) - 3.54 mass of water (g) - 2.78 MolarMass MgSO4 = 120.38g/mol MolarMass H2O = 18.02g/mol Based on those results, determine the molecular formula of the hydrate. Homework Equations n=m/M...

Homework Statement "A gaseous binary compound has a vapor density that is 1.94 times that of oxygen at the same temperature and pressure. When 1.39g of the gas is burned in an excess of oxygen, 1.21 g water is formed, removing all the hydrogen originally present. (a) Estimate the molecular...

I’ve been scratching my head (and working in ms excel) about the following for about 6 hours and would greatly appreciate it if somebody could help me. Basically, I am trying to figure out WHY the density of water is approximately one gram per cubic centimeter (at 1 atm pressure and 4 degrees...

I have a book on Gaussian but it mainly just explains how to use the program, it only gives very brief explanations of the theory behind how Gaussian does what it does. I want to gain an understanding of how Gaussian performs the various types of calculations that it can do. I understand the...

Question on Molecular Orbital Theory (and the "dot" that represents no interaction) I have a question about the "dot" that represents no interaction between orbitals. For example, in the molecular orbitals of H3, there is the lowest energy molecular orbital that has two bonding interactions...

1. Homework Statement [/b] Calculate the function for N2 at 300k d(vx)= (m/2pikT)^1/2 exp(-(mv^2/2kT) I have to be able to use this equation for varying velocity from -1500 m/s to 1500 m/s The Attempt at a Solution Boltzmann constant = 1.3806503 × 10-23 m2 kg s-2 K-1 N2 mass= 0.0280 kg So...

So, I really like my biology classes. It's cool to learn things about biological systems that I can apply towards ideas of medicine. Biology encapsulates so many finds. I really like the courses but I also want a secure income down the road that will lead to an interesting career(Why I passed...

Homework Statement Given the relationship Cp/R as a function of Temperature, approximate the number of fully excited vibration modes at a given temperature for a given molecule. 2. The attempt at a solution I have looked through several textbooks and many web sites, but I can't find this...

Assuming a density of exactly 1 g/cm3 (assuming that even matters) So, at 1 kelvin, how fast do the molecules actually move? Is it a direct, or exponential increase to 2 kelvin? This might be a stupid question. I'm not a scientist.

i'm trying to do my ap physics summer work, but I've been having a hard time trying to teach this to myself. i do really well in class, but i need a little bit of guidance to help explain how to use the equations the right way. i'm currently stuck on a question about vrms an it's relation to...

Hey there, I am currently working on creating models in Abaqus of Wrist implants to see how they respond under different loading conditions. I have used Mimics to export orphan meshes of the wrist bones and also imported the wrist implant itself. My simulations seems to be running fine all...

M g of a substance when vapourised occupy a volume of 5.6L at NTP, molecular mass of the substance will be? Here, what does the NTP refer to [normal temperature pressure?] options are M, 3M, 2M, 4M

Homework Statement 1. What is the molecular shape of Hydrazine N2H4 w.r.t. N atom? 2. H2S and H2O, which one has a larger bond angle? 2. The attempt at a solution 1. Trigonal Pyramidal is the answer given. But Hydrazine has 5 atoms around its central atom and I'm unable to fathom...

Hello everyone! I have constructed a model of a silicon crystal, consisting of 64 atoms, for my various needs of testing physical phenomena in that substance(Silicon). At present, rather annoyingly, I am still stuck at the basic operational level, that is, calibrating the system to an expected...

Perhaps too subject-specific of a question for this forum but most other bio forums I've seen are molecular-bio oriented whereas this is more of a structural/biophysics question. I've been using PyMol relatively frequently the last couple of years and one area where I've repeatedly been stymied...

I'm thinking of absorption of infrared radiation by gas molecules. This interaction results in an increase in vibrational KE. For the kinetic definition of temperature only translational energy is considered. Nevertheless as gases absorb infrared their temperature goes up. What are the important...