Atom Definition and 999 Threads

How do you calculate the surface atom density of an fcc(111) surface expressed in terms of a? I've managed to do it for fcc(100) and fcc(110), but I can't seem to figure it out for fcc(111). Any help would be greatly appreciated!

Eisberg and Resnick says that the condition for stability of the atom is: k Ze2/r2=mv2/r What I fail to understand is why the Z isn't square too. I mean surely you have Z electrons interacting with Z protons which which would surely give q1q2=(Ze)(-Ze)=-Z2e2? What am I missing?

This ought to be simple, I think. But I haven't found a consistent way to think about things yet. Is it as simple as adding up all the spins of the elementary particles in the particle and checking whether the total has inter or half-integer spin? Homework Statement State whether the...

as far as i know it takes certain amount of energy for an electron to change orbit now what i am wondering is why the energy required for an electron to change orbit doesn't change when close to let's say another positively(or)negatively charged atom thank you for your time and sorry for the...

Is the ionization energy of Francium to high to be achieved with just one photon? And another quick question, how hot must the light-emitter get before it begins to emit x-rays, and then how hot for gamma rays?

Why can't an electron have a even lower energy level in atom and be closer to the nuclei? (as the next step is to fuse with one of the protons and make neutron.. )

I am looking for a fairly simplistic answer to why different "shells" in atoms can only hold a specific number of electrons. There is so much based on valence electrons and how many electrons make a full shell but, do we know why atoms "seek" a full outer shell? It seems like there should be a...

Hi I am reading about the force of a coherent EM-beam acting upon an atom, and I have a question in this regard. It is regarding the explanation on page 150 of this book, starting from "The geometric approximation of atom optics is valid when"...

I almost have the answer, I'm sure there's just a minor flaw in my reasoning. Here it goes: We're given that the angular momentum of the atom is integer multiples of h-bar (n\hbar) (integer depending on the orbit). Now the centripetal force is given by F = \frac{mv^2}{r} = \frac{p^2}{mr} =...

Hi In the following paper (on page 5) is the standard derivation of the force acting on an atom, whose center-of-mass motion is described classically. What I don't understand is the step taken from (5) to (6). The QM-version of the force is defined using Heisenbergs Equation of Motion (so...

I know that when a photon strikes an atom, it excites an electron, which then will re-emit the photon when it returns to normal. But what is actually happening here? Is it really as simple as that, or is there something more fundamental going on here, like how nuclei are bound together using...

What object would represent the size of a grain of salt at this scale? Would it be bigger than Earth?

Ok i don't know anything about quantum physsics but when i was reading about it( for the sake of learning new stuff) i had this question :- Does the attraction between protons and electron play a role in determining where the electron probability is maximum at? I was seeing the graph of...

If a a 1s hydrogen atom is placed in a B field, how many energy states will it split into?

If I may, I would like to give this question another try, especially if guys with some cabala in QFT can address it. Is it possible to show in the relativistic quantum theory, that the hydrogen atom is stable? (Electron will not fall onto the proton)? I explain. In the non-relativistic...

helo can someone tell me where I can find detailed explanation about normalization and orthogonal properties of the radial functions since the books I've been reading do not explain enough, I thought Laguerre associated polynomials resolved the problem directly but this is not the case, the...

Homework Statement Consider the following energy levels of a hypothetical atom. E4 -1.0 10-19 J E3 -5.0 10-19 J E2 -10 10-19 J E1 -15 10-19 J (a) What is the wavelength of the photon needed to excite an electron from E1 to E4...

About the atomic radius, as a starter it was mentioned (and correct me if am wrong) that: Rcation < Ratom< Ranion (And we'll know the size of the atom based on these) Then it was mentioned that: Radius of atom of a certain element increase if we walk straight downwards along a column in the...

How big would the nucleus be? A grain of sand (0.1cm diameter) A marble (1cm diameter) It's a grain of sand right(?); since the relationship between the diameter of an atom and its nucleus is 100,000 to 1. 150/0.001= 150,000

Homework Statement I have a problem on my assignment in which I am required to find the specific heat of a two atom basis (diatomic) using the Debye model. My problem is coming up with the density of states for a diatomic setup in 1D. Homework Equations Density of state...

Homework Statement i) Write down an expression for the LJ cohesive energy of a molecule consisting of four atoms lying on the corners of a square of side a. ii) Deduce the equilibrium value of the nearest-neighbour separation, a, assuming the molecule retains its square shape iii) What...

Hi everyone! So we're learning about the Hydrogen atom in QM and I'm having trouble reconciling something in my head. We're looking at potentials that are only radius dependent, like the Coulomb potential. Now, I know the math. I see that we assume the wave function can be separated into the...

Homework Statement In Bohr’s hydrogen atom, the frequency of radiation for transitions between adjacent orbits is νBohr = (En+1−En)/h. Classically, a charged particle moving in a circular orbit radiates at the frequency of the motion, νorbit = v/2πr. Find the ratio νBohr/νorbit for the...

using special relativity m = m0/(1-v^2/c^2) on an electron orbiting with a speed of 2.01 * 10^8 m/s in an atom,estimate the percentage corrections to the n=1 energy in a uranium (Z=92) atom. so to find the energy I first need the reduced mass, u, for En = u*(9e9)^2*e^4*Z^2/2(h bar)^2*n^2. How...

Homework Statement Experimental evidence suggests that the nitrogen atom in ammonia, NH3 , has four orbitals in the shape of a pyramid or tetrahedron. Draw an energy-level diagram to show the formation of these orbitals. (Hint: No electron promotion is required.) Homework Equations...

Homework Statement The first part asks to find the necessary momentum of a "relativistic projectile particle" in order to resolve a diameter of 10^-10m (i.e. the atom). The second part asks to find the corresponding energy of the projectile particle, in GeV. Homework Equations λ = h/p E2 =...

Two quick problems, not sure whether the 2 are related or not: 1) The question is: A sodium atom in one of the states laveled 'lowest excited lvels' remains in that state, on average, for 1.6 x 10^-8 s before it makes a transition to the ground level, emitting a photon with wavelength...

What is the Temperature of an atom moving at the speed of light? Since absolute zero is the lack of activity and energy and since no physical object can move faster than the speed of light What is the temperature of an atom moving at the speed of light? Light is either a particle...

When (what year and by whom?) was it discovered that the hydrogen potential is V=-1/r ? I imagine this was deduced from experimental data... amirite? Quite urgent... From wiki it looks like it was found in teh 1920's but I'm not certain so I just want to check. Thanks in advance

when proton and electron combine to form hydrogen atom(ground state) what is the source of radiation emitted

Homework Statement The average function of the H-atom in its ground state is ψ(\vec{r})=(1/(πa03)1/2exp(-r/a0) a0: Bohr radius a.What is the probability i. P(\vec{r})d3\vec{r} that the electron will be found in the volume d3\vec{r} around \vec{r}? ii. Pdr that the electron will be found...

Find the first radius, the energy of "connection" and the wavelenght of the first risk of Lyman series of a hydrogen atom that electron has been "replaced" for a meson with negative charge with a mass 207*electron mass. Radius: r = (h^2*n^2)/(4pi^2*e^2*k*me) we know all constants so we just...

Homework Statement Determine for the hydrogen atom states 1s and 2p the expectation value of the radius r and the associated mean square error Δr. Homework Equations Wave Functions for 1s and 2p from Demtroeder's Experimental Physics Volume 3 (it says "The normalized complete...

This is a problem that's been bothering me for a while. For electrons "in" hydrogenic atoms, do the electrons in states for which l=0 actually orbit the nucleus, or would they only ever be observed to be moving radially (assuming they could be directly observed in that way). Here's my logic...

There are two cases I could think of: Case 1: The electron is constantly in a state of unrest due to the hiesenburg uncertainty principle, and the ZPE of that electron is caused from the state of its own unrest. Case 2: The electron is constantly in a state of unrest becuase it is...

I'm trying to follow a derivation of the ground state energy of Helium using perturbation theory. I've made it through most of the derivation but I'm stuck at the following integral Homework Statement Find the value of C where C=\frac{1}{(4\pi)^2}\int...

Why is it impossible to change the number of protons of an atom? Is it because the protons are in the nucleus? How can we change the number of neutrons then?

I've been searching and trying to find an answer to this. I'm not scholar or physics major. I'm asking for some guidance about this subject. The big bang theory, leaves me with the impression that atoms can change size. Is this true? Can gravitational forces compress, can atoms...

Homework Statement Estimate the ionization energy of Lithium. Neglect the repulsion between the electrons. Homework Equations what is the equation that can be used here? There are thousands of tables in the web having tabulated the values of various ionaziation energies. But one can hardly...

As I know from the laws of chemistry,to form H_2 the H atoms must have opposite spin. What if they have the same spin? I mean, can an H atom rotate to swap his spin (i'm not expert of the dynamics of spin), or there is no way to couple them? In the case I have a gas of H with all of them...

Homework Statement Write down the electonic configuration for the O atom. Write down the quantum numbers (n,l,m_l,m_s) for each one of the electrons. Homework Equations Pauli exclusion principle. Least energy principle for filling the shells. The Attempt at a Solution...

Hi, I refer to the second edition (international edition) of Griffiths. He proves that the total fine structure correction (spin orbital plus relativistic) is given by E_{fs}^{1}\propto (3-\frac{4n}{j+1/2}) After that, he writes this. "Fine structure breaks the degeneracy in l (that is, for a...

im trying to study an isolated atom(Boron) and i can't for the life of me figure out what to do with the total magnetisation, which is defined as : further more: what are these guys talking about? is this explained out in detail somewhere in ENGLISH for humans? cheers mechdude

Hi, everyone! I would really appreciate your help with this one! I've been looking at a simple problem, linearly polarized excitation scheme in a two-level atom, J_g=J_e=1. At first orientation of coordinate system is such that light is polarized along y direction and propogates in z...

Homework Statement In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. What is the electron's orbital frequency? What is the effective current of the electron? Homework Equations Freq * Wavelength = Speed of...

Is there a table or a graph out there that states the amount of energy needed to split an atom? I know about ionization energies and all that, but there wasn't anything on the internet on how much energy is required to ionize the whole atom. Thank you in advance

Homework Statement In Bohr model of the hydrogen atom, the max. kinetic energy that an electron can have is around 13.6 eV, as it would otherwise not be confined to the atom. Uncertainty Principle: ΔxΔy ≥ h/2π a) Find the max. momentum of such confined electron. b) Use Uncertainty Principle...

Calculate the electrostatic force between a proton and a gold nucleus Au with a distance 7.5x10-13m 19797Au The Electrostatic force is (Q1Q2)/4∏ε0d2 Two things I want to know, the charge of the gold and how to find the charge of Atoms! All I need to know is the charge, I can do the rest!

Calculate the expectation value of the potential energy for an electron in a 1s orbital for a hydrogen atom Ive determined the potential energy operator to be V=-e2/4∏ε0r and a wave function of ψ= (1/4∏)1/2 therefore i get <V> = ∫∫∫ψ*Vψr2sin∅drd∅dphi integrals from 0 to r...

Homework Statement According to the molecular biology book I am reading, when a chemical bond breaks, the energy in the bond is released in the form of heat. which is to say, when a chemical bond breaks the entire atom's speed increases (the atom gains 'heat energy'). But what is...