Atomic Definition and 853 Threads

Homework Statement Naturally occurring iodine has an atomic mass of 126.9045. A 12.3849-g sample of iodine is accidentally contaminated with 1.00070 g of ,129I a synthetic radioisotope of iodine used in the treatment of certain diseases of the thyroid gland. The mass of129I is 128.9050 ...

Hi, I'm looking for any resources explaining time dilation at the atomic level. I can't find anything on it sooo If anyone could please refer me that would be helpful. kind regards

Rutherford postulated that the electrons are moving around the nucleus of the atom in circular trajectories, right? My professor said that or I believe in it or there is no more chemistry to study, because this does not agree with some law of Maxwell's theory of electromagnetism. He said...

Homework Statement Greetings everyone I have been been asked to write a 10 page essay on Quantum Energy levels in atomic, molecular, nuclear and solid state physics. My problem is that this is such a huge topic and my knowledge of quantum energy levels and solid state physics is limited...

I'm trying to understand what fire is at an atomic level. I'd appreciate it if you guys could correct me where I am wrong and fill in any gaps. 1: When you heat an object it introduces energy. 2: This energy causes the atoms in the object to jiggle around. 3: At some point introducing the...

Please help me in clearing my basic doubt We all know that positive charges are concentrated at the centre of the atom , known as nucleus and electrons revolves around the nucleus in orbits. Is it necessary to assume that orbits are circular ?

So I am reading about how an atomic clock works , So they shoot microwaves at cesium atoms and the right microwaves will cause an electron to jump up to the next energy level , are they using this to tune the microwave laser so they know what the frequency of the laser is . and when they...

Can anyone help. How do I calculate mass density of aluminium, given the atomic density of 6.04 X 10^22. I understand that Density = Mass/Volume. but the question confuses me. Thanks

Homework Statement Hi folks! :smile: This is just a conceptual question that has arisen during some reading. At one point the author states that for the reaction: CO_2 \leftrightharpoons X_{CO}CO + X_{CO_2}CO_2 + X_{O_2}O_2 where X is the mole fraction of each component at equilibrium...

Can the absorption spectrum of an atom be shifted significantly using electric or magnetic fields ? such that to turn red to blue or something ? Another question, can atoms be excited to a certain energy level by applying external fields only with calculated energy ? thanks

Atomic clock should record different time depending on their geo location: different latitude -> different rotation speed. Question: The most precise time on Earth - where is it valid? On what Latitude?

Homework Statement I am preparing a presentation on nuclear reactor technology. To demonstrate the mass-energy equivalence, I am trying to calculate the binding energy of some heavier isotopes. The problem is that, when I substitute the values that I have into the equation, I get a...

Homework Statement Given that the total cohesive energy, U, in an ionic crystal as a function of nearest neighbor distance, R, between two ions +e and -e is given by: U(R) = \frac{A}{R^n} - \frac{\alpha e^2}{4 \pi \epsilon R} show that at equilibrium: U(R) = \frac{\alpha e^2}{4 \pi...

Hi, I want to know what the important quantitative differences between the light produced by an atomic gas laser and that produced by a semiconductor laser are? I know that produced my atomic gas lasers are low power but high collimation, but semiconductor lasers seem to have higher power...

what i did: 27.40 * 0.781 = 21.4 52.9 * 0.811 = 42.9 62.6 * 0.856 = 53.59 there is a hint that says i have no idea how to get the common factor with those numbers.. btw i had no idea where i can post this in here so i posted here :X

Hey everyone, I've noticed that when paramagnetism is derived in the context of stat mech, we only consider the energy levels of the perturbation. Essentially, we take the fine structure of hydrogen, and we perturb it with a B-field, causing the weak zeeman effect to split the energy levels...

Are there any other good books such as LIM series which include solved problems on QM,Stat Mech & atomic physics ?

I can't even claim to understand 'spin' as a property (even after reading that big thread about it :P) but I'm sure with the amount of discussion that generated, this could be worth talking about http://www.ohio.edu/research/communications/spin.cfm

in an experiment we looked through the diffraction grating to see the spectrum made by a helium lamp. we measured the distance along the meter stick to the point where we saw each color. based on that distance how would you calculate the wavelength of the light that was seen? would you...

How shall diffusion of precursor atoms be treated if the core is in liquios state(as is MSR)[I mean regarding to its low volumetric density, shall we treat it as gas-liquid diffusion and is diffusion approximation or even transport theory valid for it anymore, what's the meaning of state space...

Is it possible to predict theoretically the maximum amplitude of vibration that atoms of a metallic species, like Copper, will exhibit at a given temperature?

I heard that the reason why we can't put our hands through a wall (or such a thing) is because of atomic electromagnetic forces pushing things away from each other (since after all, things are mostly empty space, and only seem solid because of the scale). I also heard that that is the same force...

Homework Statement First of all, this is my first post here, so I apologize if I format things incorrectly. I'm working on a Matlab script to evaluate the tunnel ionization rates via the PPT model given the correct set of input parameters. The rate equation I am using contains equations...

Forgive me if this has already been discussed. I've been searching and haven't found it. When summing the spin of an atom in the Russell-Saunders coupling scheme, some texts include the spin of an odd nucleon, and some don't. For example, if an atomic energy state is described as ${3}^P_{2}$...

I did not quite understand the "stimulation" part. How does the photon coming near the excited atom force this atom to emit another, identical (from the physical properties point of view) photon? More precisely, how do the stimulating photon and the atom interact?

Calculate the speed and radial acceleration for an electron in the hydrogen atom. Do the same for the Li++ ion. v = e (4pie0mr)^(-1/2) ar = (v^2)/r r ~ 10^-10 m v = 2.24 x 10^6 The book makes note that we can allow a nonrelativistic treatment since the velocity ~ .007c. And for the lithium...

How does atomic radii decrease when we move left to right in a periodic table? Though the nuclear charge increase as a result of increase in number of protons,the same increase is occurring in number of electrons.

Greetings Physics Forums! This is my first post. A physical phenomena that I know for a long time is that when an atom (let's say hydrogen) has an electron that make a quantum jump from a higher energy state to a lower it emits a photon. Suppose the hydrogen atom is isolated from the external...

Can anyone recommend me some papers explaing how cesium atomic clock works?

I recall a physics teacher demonstrating an experiment where he transferred a droplet of oil to the surface of water and carried out some calculations to determine the radius of a carbon atom. I was hoping to replicate the experiement- However I forget the details. Has anyone seen this...

In an atomic nucleus, there is protons, and neutrons. The protons are positively charged and the repel each other. However, there is an "opposing" that helps to keep the nucleus in a piece instead of breaking apart. Does anyone know what kind of force is this? And what causes this force to be...

An article in Wired concerning a new atomic clock has as part of its lead sentence "The new timekeeper could one day ... detect the slowing of time predicted by Einstein’s theory of general relativity." See http://www.wired.com/wiredscience/2010/02/quantum-logic-atomic-clock/#ixzz0f1IPhJLR...

Do substances radiate particles? Is it the wind brushing up the surface particles of the substance? Do dense materials usually have less smell?

Homework Statement In the presence of a magnetic field, the energy of an atomic energy level is changed by the quantity: Emag=g\muBBM (i) Expain the meaning of the terms in the expression. (ii) Into how many levels is the ground state of the sodium atom split? (iii) For each...

Homework Statement 1. Let -Q charge be uniformly distributed over a sphere radius R. Find f(|\vec{G}|), the atomic form factor. 2. Let the incident xrays have wavelength \lambda, determine the dependence of f(|\vec{G}|) on \theta, the scattering angle. Homework Equations...

Hi, I always heard the textbook presenting the idea that atom is mostly compose of space by giving the analogy that if the whole atom is the size of a stadium then the nucleus would be the size of an eraser in the middle of a stadium, and the electrons flying around the stadium but if this...

Hello everyone. Just a quick question: Could somebody explain to me what atomic concentration is, and whether there is a list of all the atomic concentration of the elements somewhere in the internet. The 1st time I heard the term, I typed it on wikipedia and google, surprisingly the...

Hello! Mercury vapour detection is normally performed at 253.6 nm, which is the lowest emission line in the UVC range. I have to figure out if a similar atomic absorption approach would be valid at a longer wavelength, specifically at 365 nm, which is an other emission line but into the UVA...

I know because E=(n+1/2)*h-bar*omega , and n is an integer , with the integers ranging from zero, to all positive values. Photons are said to be massless physical quantities and according Einstein's theory of special relativity (or general relativity) mass and energy are equivalent. So if a...

I know it isn't the anniversaries of these two horrific and deplorable tragedies and I know this is kind of ancient history for people not directly impacted by this event, but I looked at the past threads in PF and could not find a discussion of this topic, so I thought I would start the first...

Hi Recently I've been pondering the causes of enormous difference in energy requirements between modeling a complex process like fluid dynamics on computer and the actual energy required in the physical fluid. In a computer, it takes hundreds or thousands of processors long periods of time to...

i am now studying the Doppler effect in a thermal atomic gas If an atom travels in velocity v along x direction at some time, it emits a photon in some direction the momentum of the emitted photon can be well approximated with the free one thus the momentum of the atom after the...

i am now studying the Doppler effect in a thermal atomic gas If an atom travels in velocity v along x direction at some time, it emits a photon in some direction the momentum of the emitted photon can be well approximated with the free one thus the momentum of the atom after the...

As simple as the questions seems, I can't seem to find an answer. 1. Can atomic hydrogen by chemical reaction, be converted to molecular hydrogen? 2. what happens when putting electrodes in a reaction that would give me atomic hydrogen? would it be collected at the cathode like molecular...

Hi, I have a helium atom in the excited state of (1s,20p), and I am told that it has 4 corresponding atomic terms. I am supposed to "write down the quantum numbers of these 4 atomic terms". As I understand it, an atomic term is specified by the 2S+1LJ notation, where S is the spin quantum...

Hi, How would you determine the relative atomic sizes of a neutral atom and an ion? I can't figure this out. It can't be that all neutral atoms are always smaller than all ions can it? For example, how would I determine if Cl- is smaller or larger than S?. (The answer is that Cl- is...

Hey guys, I'm working on some experiment designs and I'm trying to figure out if its possible to isolate a single atom of a particular element for insertion into an inert gas chamber, so say for eg, i want to take carbon atoms, one at a time, and inject them into a neon gas filled chamber, is...

any can answer this? that why J.J Thomson strike gold by alpha particles in his experiment by which he propose model for atomic structure?

for the calculations in one of my homework questions, i need to use the atomic radii of Fe and Ni, the problem is that every site i come across gives me different values Fe wikipedia 126pm physlink 1.72A chemicool 140pm how do i know which one to "trust" ?

Homework Statement An atomic nucleus is in an excited state. It decays to its ground state with the emission of a gamma ray having energy, Egamma = 24.0 keV. The nucleus has a mass of 9.53e-26 kg. What is the recoil speed of the nucleus? (Note: This may be an inelastic collision)Homework...