Atomic Definition and 812 Threads

Been many years since I took general and org chem and am currently reading general chem textbook as refresher. Came across defintion of amu (atomic mass unit). Text says that the mass of the carbon-12 atom is defined to be exactly 12 amu. However, a couple of pages over, I read that the mass of...

Can a proton or netron be compressed? Why don't individual neutrons behave like mini-black holes? What about the nucleus of an moderate weight atom; how much empty space is there in the nucleus of an atom? A lot of articles refer to the gravitational pull within a black hole, but what...

Speed of Light c= \frac {1} {\sqrt{\varepsilon_0\mu_0}} Phase Velocity v= \frac {1} {\sqrt{\varepsilon\mu}} Electric Permittivity of Free Space \varepsilon_0 = 10^{7}/4\pi c^2 \quad \mathrm{(in~ A^2\, s^4\, kg^{-1}\, m^{-3}, \, or \, F \, m^{-1})} Magnetic Permeability of Free Space...

Hello all, I wonder if anyone can help me with a problem I don't understand about atomic levels. Given an excited state of He with electronic config (1s,2p), I need to find all possible atomic levels. The answer sheet lists 4 levels: 1) S=0, L=1, J=1 2) S=1, L=1, J=1+1=2 3) S=1, L=1...

Hello How can a monochromatic light induce a transition ( absorption ) between two energy levels whose energy difference doesn't match the frequency of the incident light ?? A treatment using time dependent perturbation theory shows that the transition will occur even when the incident...

I am trying to complete some chem homework in microsoft word, but I need to write the atomic symbols. Is there any way I can write the mass number over the atomic number. Can I use sub and super script at the same time in the same place?

Quoted from http://hyperphysics.phy-astr.gsu.edu/hbase/gps.html#c1" How do they know which of the points is the correct one? (see sentence in blod) Thank you!:approve:

say an atom absorbs only a certain amount of energy. how long dose it take for the atom to release its obtained energy?

Hi all My question arises in the context of a photon which is emitted by an atom located inside a cavity. From quantum mechanics, a photon is a quantum of an electromagnetic mode, but we also use the definition which says that the photon is what is released by an atomic system when its...

hey just wondering where I went wrong Iridium Crystallizes in a face centred cubic unit call that has an edge length of 3.833A The atom in the cantre of the face is in contact with the corner atoms calculate the atomic radii of the irridium atom I did this using pythag...

Hi guys I understand that the unified atomic mass unit is defined as 1/12 of the mass of a carbon-12 isotope and has a value of 1.66 X 10^-27kg. Why is this value slightly different with when I use the calculation 0.012/6.02 X10^23? Why in theory, is the mass of a protn different from a...

I have searched some books I have on Quantum Physics, and so on, but I still haven't found any useable material to learn about the Pauli exclusion pinciple, atomic orbitals, why the Periodic Table exists, or things like that, in an informal way. Thanks, Neohaven

Hello, Just like in the topic, what causes electrons to move around the nucleus in perpetual motion (they never stop). For now, it's the only question. I'll have some more when I get the answer. p.s Actually, let me ask another one. A little bit unrelated. What causes electrons to move in a...

I also wish to understand atomic weapons... The TV said Iran can build a 'device'... I read here at the forum that Nuclear plants are limited to 5% pure fuel... I assume an H-bomb is more than 5% pure fuel... Is the media just trying to spook us? Also if my research is correct..it...

I am at loss to understand (from a layman's point of view...with some math-stuff, too) how an element's electron(s) can jump the quantum fence. An element, any element, as shown on the periodic table, has certain characteristics within its 'earthly' domain, the 3-D world we live in. What causes...

Studying for finals and this is one of the reveiw questions our teacher wanted us to take a look at. A little help please, i got started somewhat as you will see below "Suppose that we have a lot of noninteracting atoms (a gas) in an external magnetic field. You may take as given the fact that...

Hello, I'm not familiar with what scientists working at accelerators say, but almost every book, and documentary movie say that Quantum Mechanics don't cover the gravity. I just gave a quick thought, well, maybe the gravity isn't there at all? Atomic level simply lacks the gravity and is only...

Greetings. I know that a centrifuge can "seperate" different elements by virtue of centrifugal force, but what effect does a centrifuge have on the atomic geometry of individual atoms? That is, since the nucleus of an atom is generally more massive than the collective orbiting electrons, does a...

I basically am having a problem understanding the units used on the atomic level such as MeV/c and MeV/c^2. I have a problem where I have a given energy of 370 MeV for a photon. This means the wavelength is \lambda = \frac{{(6.6261*10^{ - 34} )c}}{{(3.7*10^8 eV*\frac{{1.6022*10^{ - 19}...

Hello, I'm writing a program, and while I have a decent understanding of wavefunctions and atomic orbitals, this one appears to be a problem I can't beat. I'm graphing various properties of atomic orbitals (wavefunction, wavefunction squared, radial probability distribution, and a cross...

I haven't had time to digest this, but - http://www.physorg.com/news10263.html I wonder how far from Disney World this place is - eh, Zz?

:smile: :smile: just searched to see what rf freq was used by NIST, and found this cool wristwatch :biggrin: http://www.leapsecond.com/pages/atomic-bill/

If an atom has a ground state energy level of -10.4eV then why is the ionisation energy 10.4 x 1.6 x 10^-19J ? Wouldn't that amount of energy just cause the electron to move to the highest energy level? I would have thought that the energy required to ionise the atom would be any value greater...

In L. I. Schiff book, one can follow his derivation of the Hamiltonian from Dirac relativistic equation and obtain the following.. \left[\frac{\vec{p}^2}{2m}+V-\frac{\hbar^2}{4m^{2}c^{2}}\frac{dV}{dr}\frac{\partial}{\partial r}+\frac{1}{2m^{2}c^{2}}\frac{1}{r}\frac{dV}{dr}\vec{S}\cdot...

This is pretty simple, just give me a quick concept should be enough, no need to go over the details. What determines the radius size again? Was it just the electrons? Say for example which is bigger, potassium ion or argon. Same electron configuration but different proton numbers. Would...

The Charge density of an electron cloud for a Hydrogen atom is given by: \rho (r) = \left(\frac{q}{\pi a^3}\right)e^{\frac{-2r}{a}} Find its polarizability(\alpha ). My work: Dipole moment p is: \vec p = \alpha \vec E I need to calculate the electric field first. The electric field...

Why does neon have more spectral lines than helium? Is the atomic spectrum based on an element's electron configuration?

Hi! to everyone on the forum. I am new and did not really know where i should of posted this thread its not homework its just a question i have. A friend of mine asked me a question about a book he read about (atomic spectra and atomic structure by Gerhard Herzberg). Gerhard Herzberg said...

My physics teacher told me that one of the innacuracies of Bohr's Atomic Model is that the nucleus (positive) would attract the electron (negative) making it move as a spiral until it collapses with the nucleus. What I don't get is why the same thing doesn't happen with a planetary system. How...

I recently made a post here asking questions that where clearly rediculous. I guess I need to be more obtuse. The reason I asked it here is that I'm looking for any possible way in which the 'tornado-like' rotation of galaxies could be explained by any kind of possible atomic structure in 3D...

Exactly how does it work when you split an atom? A neutron is shot at a nucleus. Does the nucleus split apart because of the force of the neutron hiting it? I saw something about the neutron sticking to the nucleus and it becomes unstable and splits. Also wonder how do you accelerate a...

What is the approximate ratio of the nuclear radius to the atomic radius for elements near the middle of the periodic table? It is supposed to be about 10^-5 but how do you get this?

Hi All, Im' trying for some members of my site toshow atomic interaction force (coulomb...) with some animations. Here is my first trial two ions with same but opposite charges... Is there an acceleration since attraction augments (like I did)? You need Flash player...

I wanted to do some research on Atomic dust. The process would take a metal and vaporize it by a high powered LASER in a vacuum and then allow the metal vapor to cool in the vacuum an then fall to the bottem of the chamber as Atomically fine dust particles of the metal. Is there any...

The question is have is as follows: In 1971 four portable atomic clocks were flown around the world in jet aircraft, two east bound and two westbound, to test the times dilation predictions of relativity. a) If the westbound plane flew at an average speed of 1500 km/h relative to the surface...

Where I can find more about models of atom? I need a name of site for example….

Can somebody please tell me what is the definition of an atomic sentence and the definition of a molecular sentence? Thanks :smile: :cool:

I have been playing around with an idea for a few years and I am interested in receiving any feedback. I am an amateur, so if there are any issues with my logic, please feel free to straighten out my thoughts. First, imagine 2 astronauts floating in space. The first astronaut has an atomic...

If some girl weighs 100 pounds or 45.45 kg E=mc^2 Energy = (45.45) x (3 x 10^8)^2 My answer was 4.9 x 10^1^8 J of E. But it's been a while and I'm not confident. Is that wrong? thanks

which is more important to the chemical behaviour of an element? cant seem to find this anwhere

Can someone help me with representing some quantities without units. I found that in atomic physics atomic units usually aren't used. For example Energy is E=\frac{-1}{n^2} Period of classical electron orbital i given by T=2 \pi n^3 Here n is Principial quantum number. How are derived these...

Interesting paper: Enhancement Mechanisms of Low Energy Nuclear Reactions Gareev F.A., Zhidkova I.E. ... 1. Nuclear processes have characteristic energies ≈ 1 MeV, whereas chemistry has a few eV per atom, molecules have a part of eV. The inner atomic shells are bound with many keV in the...

I heard that each our bodies have on average a billion of shakespears body's atoms in them (A short history of nearly everything, Bill Bryson). Is there any truth in this, does that mean we have on average a billion of every persons atoms that has ever lived?

An emission spectrum can contain wavelengths produced when an electron goes from the third to the second leve. So could you see this like in the absorption spectrum? Why?

Suppose that the fermium-252 nucleus could undergo a decay in which a (beta-) particle was produced. How would this affect the atomic number of the nucleus? Explain briefly. This looks pretty easy, but I think it's trying to trick you. Thank you for helping.

I have my doubt,solution and question in the attachment that followed.Thanks for anybody that spend some time on this question.

hello can anybody tellme about atomic numbers,valances,n related topics :smile:

I am having major trouble trying to figure the concentration of a substance that is given by the AAS. Here's the question: To determine the iron content in a 'Milo' milk drink, a 5ml sample was diluted to 50ml. the absorption of the diluted solution and of several standard solution were...

how do you convert the atomic mass unit into kgs?

How would you go about to solve this quesiton? I thought that to calculate this i had to set up an equation as: let x = the percentage of 85-Rb 84.91*x + 86.91*(1-x) = 85 x = 96%, but that's obviously wrong. How do i solve this question?