A nucleus made of protons and neutrons surrounded by a cloud of electrons equal in number to the protons.

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136 views

How can a strong water current be cold

This is a layman question. If heat is the motion of atoms, how can a fast moving water current be cold?
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1answer
294 views

How can we describe the electrons of multi-electron atoms (i.e. not Hydrogen) when equations/analytic solutions only exist for Hydrogen?

I've been digging into emission spectra of different elements and found that such things as the Rydberg equation, Bohr's model, and quantum mechanics can only fully describe the single electron in the ...
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2answers
6k views

What exists in the Space between atoms

Apologies to all if this has been asked before, I searched but was unable to find one similar. This is a question that has been bugging me for a while that i haven't really been able to find a ...
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3answers
1k views

What happens if we put together a proton and an antineutron?

A hydrogen nucleus consists of a single proton. A 2-hydrogen (deuterium) nucleus consists of a proton and a neutron. A tritium nucleus consists of a proton and two neutrons. This makes me wonder how ...
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2answers
4k views

How does electron move around nucleus?

I need to get a nice picture about how electron moves around nucleus? I find concept of probability and orbitals quite difficult to understand?
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1answer
784 views

Energy required for ionizing Helium

The energy required to remove both electrons from the helium atom in its ground state is 79.0 eV. How much energy is required to ionize helium (i.e., to remove one electron)? ...
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2answers
121 views

How does one subtract two light beams?

From what I understand, it seems like you can only "add" beams together. You can use a beam combiner, basically using a beam splitter in reverse, to combine two beams. In homodyne detection, you use a ...
2
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1answer
462 views

Dark and bright areas around atoms in a scanning tunnelling microscope image

Recently IBM created world’s smallest ever animation on an atomic scale video. Researchers made the animation using a scanning tunnelling microscope to move thousands of carbon monoxide molecules to ...
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1answer
340 views

Difference between atom and elementary particle questioned

Hydrogen ion doesn't have one electron which clearly mean that it has only one proton..So hydrogen ion is only a proton. Am I right, please make it clear. If hydrogen ion and proton are same that how ...
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1answer
102 views

Atoms in our body

Our body of course exchanges some atoms with environment every day however are there some of atoms which stay with us a life time?
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1answer
143 views
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0answers
35 views

Electron Configuration and Binding [closed]

Boron with an electron configuration of $1s^22s^22p^1$ has an atomic weight of $10.811u$. What is the total binding energy for 11Bs if $Mn = 1.008665u$ and $Mp = 1.007825u$. I cannot find anything ...
5
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2answers
451 views

Why is there a factor of 1/2 in the interaction energy of an induced dipole with the field that induces it?

In this paper, there's the following sentence: ...and the factor 1/2 takes into account that the dipole moment is an induced, not a permanent one. Without any further explanation. I looked ...
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1answer
485 views

What is longitudinal relaxation time and transverse relaxation time? [closed]

How do we define the longitudinal relaxation time and transverse relaxation time?
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0answers
79 views

How large must the Quantum teleportation fidelity have to be in order for it to be useful?

This question relates and stems from my original question. Please read this one and the comments before answering this question. Quantum Teleportation Fidelity I know that for discrete variables ...
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1answer
2k views

Why is carbon dating limit only 40,000 years?

For an example, when they tried to get the carbon dating for presence of Aboriginal people in Australia they get to the number 40,000. But it could be much earlier. Why is that 40,000 years limit for ...
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2answers
220 views

Why is electron presented in books, pictures as a sphere?

Why is electron presented in books, pictures as a sphere, when in fact it's not?
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3answers
2k views

Can the solar system really fit in a thimble?

Almost every time somebody talks about atoms, at some point they mention something like this: If we remove the spaces between the atoms and atomic components, we can fit the solar system in a ...
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2answers
3k views

The number of degrees of freedom of a monatomic gas

Suppose that I have a monatomic gas sample consisting of $N$ atoms (e.g., $N$ argon atoms); thus there are no vibrations or rotations. How many degrees of freedom does the system have? Does the ...
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0answers
142 views

why is the transition $3p^53d^2 \to 3p^63d^1$ (hydrogen atom) forbidden?

What I was thinking is that in 3d subshell (l=2) we have two electrons with $$m_l=-2$$ (spin up and down) and if we move to 3p we will fill the last vacant position - that is $$m_l=1$$ with spin down ...
2
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1answer
110 views

Is the spin state of an atom related to the polarization of the photon it spontaneously emits?

From literature I've been reading, I find that scientists are able to "map" atomic states onto photon states. Are they talking about spin states and corresponding photon polarization states? Can ...
2
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1answer
215 views

Why do some liquid metals have anomalously-high surface tension/heat of vaporization ratios?

In a didactic article, Victor Weisskopf estimated the size of molecules in a liquid from measurements of their surface tension and heat of vaporization. If atoms are exceedingly small, then only a ...
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0answers
54 views

Where do electrons get the energy to remain in orbit? [duplicate]

As we know electrons continuously revolve around the nuclus without falling in it at a high velocity beating it's force of attraction. My question is where do electrons get energy to revolve around ...
6
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2answers
391 views

Do the energy levels of electron orbitals change relativistically?

When an electron emits a photon from changing energy levels, the frequency of the photon depends on the difference between the energy levels. But if someone is moving with respect to the atom, the ...
14
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1answer
1k views

Turned to steel in the great magnetic field

This is obviously a "fun" question, but I'm sure it still has valid physics in it, so bear with me. How great of a magnetic field would you need to transmute other elements into iron/nickel, if ...
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2answers
104 views

Quantum yield and spontaneous decay

I'm trying to figure out how many atoms are decaying spontaneously in a span of 2 seconds. Let's say that the quantum yield is 0.45, and that the lifetime "τ" (tau) is 10 microseconds. Then I found ...
2
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0answers
79 views

Where to find probability density plots for all elements?

Does anyone know where I can find something similar to this, but for all elements? I would love to find something with the same image quality. Also, is there any software that can produce images ...
2
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1answer
164 views

How is energy transferred between atoms in a collision?

Consider two bare protons. One (A) is stationary (relative to some arbitrary massless observer); the other (B) is approaching A at 1 m/s. When they collide, I assume that they bounce. What is the ...
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2answers
190 views

Does hidden variable quantum mechanics imply the collapse of atoms(electrons falling into the nucleus)?

why do atoms not collapse on themselves. Doesnt this problem rule hidden variables as invalid as the heisenburg uncertainty is the solution to the problem because it says electrons exist in a ...
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3answers
258 views

Do electrons in multi-electron atoms really have definite angular momenta?

Since the mutual repulsion term between electrons orbiting the same nucleus does not commute with either electron's angular momentum operator (but only with their sum), I'd assume that the electrons ...
2
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1answer
425 views

What is the spatial mode of light or the spatial mode of a massive particle?

I'm extremely confused by what physicists mean by the spatial mode of light. I am also equally if not more confused by what the spatial mode of a massive particle is. Can anyone help me out by ...
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1answer
444 views

Elastic collisions in Franck-Hertz experiment

Looking at a Franck-Hertz experimental setup, and given a potential difference such as $4.0\ V$ which is too small to excite out the first electron orbital, the electrons moving through the tube will ...
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3answers
1k views

What does a subatomic charge actually mean?

I was recently reading a popular science book called The Canon - The Beautiful Basics of Science by Natalie Angier, and it talks about subatomic particles like protons, neutrons and electrons in ...
8
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2answers
18k views

What is in the space between a nucleus of an atom and its electrons?

There is a common analogy about the structure of an atom, such as the nucleus is a fly in the centre of a sports stadium and the electrons are tiny tiny gnats circling the stadium (tip of the hat to ...
2
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2answers
294 views

What's the difference between two Hydrogen atoms?

If we are given two Hydrogen atoms, would the only difference between them would be their quantum state (Energy level or eigen value, and the corresponding Orbital or eigen state) and their location ...
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1answer
2k views

Why isn't Hydrogen's electron pulled into the nucleus? [duplicate]

Possible Duplicate: Why do electrons occupy the space around nuclei, and not collide with them? Why don’t electrons crash into the nuclei they “orbit”? From what I learned in chemistry, ...
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2answers
476 views

Is it possible to recover the old Bohr-Sommerfeld model from the QM description of the atom by turning off some parameters?

Is it possible to recover the old Bohr-Sommerfeld model from the QM description of the atom by turning off some parameters? Can we use Ehrenfest's theorem (or some other scheme) to reduce the QM ...
2
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4answers
238 views

Computer Science Modeling of Physical World

I am curious what efforts have been made to date to define virtual computer worlds based on the physics we know in the real world? I think it would be awesome to say start off with an atom defining ...
7
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2answers
634 views

why dosen't a charged particle radiate energy in circular motion in a uniform magnetic field?

I have studied in my Physics course that one of the drawbacks of Rutherford's atomic model was that when an electron will revolve around the nucleus, it is undergoing acceleration and so it should ...
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1answer
62 views

Rotation of diatomic homonuclear molecule

I know that the rotation energy of a diatomic homonuclear molecule is $E_{Rot}=\frac{\hbar J(J+1)}{R^2 M}$. Does the axis of rotation depend on $J$? With respect to which axis does the molecule for ...
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1answer
131 views

What is changed when proton has finite radius?

How the field and interactions are changed when we assume that proton has finite radius in atom for example? What gives the finite size effect? Is it the higher moments of multipole expansion?
1
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1answer
396 views

Do atoms expand with universe? [duplicate]

Possible Duplicate: Why space expansion affects matter? Why does space expansion not expand matter? As we know, the universe is expanding, galaxies are away from each other. But what ...
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4answers
413 views

Spontaneous radiation

The usual explanation of spontaneous radiation is that the energy eigenstates are perturbed by QED interaction, so that the eigenstates obtained from single-particle QM are no longer eigenstates of ...
3
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2answers
1k views

Energy shift between hydrogen and deuterium

Stated: The atomic spectra of hydrogen and deuterium are similar however shifted in energies. So im trying to explain why it is that the emission lines are shifted and how they are shifted. Since ...
3
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4answers
2k views

Bohr's model of an atom doesn't seem to have overcome the drawback of Rutherford's model

We, as high school students have been taught that-because Bohr's model of an atom assigns specific orbits for electrons-that it is better than Rutherford's model. But what Rutherford failed to explain ...
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2answers
411 views

A basic confusion about what is an atom

Wikipedia defines atom as The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. and defines electron as: The ...
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0answers
28 views

How the radio-freqency magnetic field helps to record fluorescence signal

Suppose a sample of atoms (say rubidium), which is exposed to constant magnetic field, is irradiated with circularly polarized light so that the electrons are excited from lower S level (F=3) to P ...
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2answers
866 views

Is there a list of all atomic electron state transitions and the corresponding radiation emitted?

Here's a quote from Wikipedia: As an example, the ground state configuration of the sodium atom is 1s22s22p63s, as deduced from the Aufbau principle (see below). The first excited state is ...
2
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0answers
142 views

Does this photon emission problem even make sense?

I came across this question in an introductory physics course awhile back and I never got over it: "A hydrogen atom has an electron in the n=5 orbit, what is the maximum number of photons that might ...
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1answer
90 views

Complex Atom Manipulation?

Is it theoretically possible for humans to manipulate Atoms to the extent that we can recreate anything we want? e.g. 'Computer, Milky Way Bar please [or other].' (out pops a Milky Way Bar after some ...