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

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Understanding Zeeman Splitting

I'm reading a standard modern physics history book ("Inward Bound" by A. Pais), and I realized I don't really understand Zeeman splitting well. In the section I'm reading, there's a short discussion ...
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7answers
2k views

Prove that an electron in a hydrogen atom doesn't emit radiation

According to electrodynamics, accelerating charged particles emit electromagnetic radiation. I'm asking myself if the electron in an hydrogen atom emits such radiation. In How can one describe ...
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9 views

What can be the result of interaction of H- ion (2.1 MeV) and stationary H2+ ion?

I believe there is Coulomb scattering. However, are there any other channels? Could the products of the reaction be H and H2, and what would be the cross section of this reaction?
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49 views

Is there a way to strip all the electrons from single atom with atomic number greater than 2

Please explain by what means electrons extraction can be done. How person can focus activity on single atom (from precision point of view) to do so? How at each step person can know how much electrons ...
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1answer
79 views

How long does an electron stay on a given orbital?

Was wondering what the average time is for an electron on any given orbital, or how often they change energy levels. Thanks in advance.
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390 views

Why did our universe become transparent to light approx. 300,000 years after the Big Bang started?

Most books say that at age 300,000 years, our universe had cooled to approx. 3000 degrees Kelvin, which allowed free-electrons to bind with atomic nuclei, which allowed light to travel, unimpeded, ...
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9k 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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0answers
30 views

How can an orbital be recognised from the wavefunction notation?

I am a student and was working up the exercises in my book when I came across a problem that required me to identify the orbital given by $ \psi_{3,2,1}\,.$ What I can work out is that the sub-shell ...
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1answer
3k views

J.J. Thomson's cathode ray tube: Why does the magnetic field bend the cathode ray downward?

The cathode ray is bent upward toward the plate by electric field and downward by the magnetic field. The first part isn't what I am confused about. However, the second part is. How did the magnetic ...
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4answers
434 views

Why can't the electron enter the nucleus?

Actually, there exists an attractive force between an electron and the protons inside the nucleus, but the electron cannot be attracted towards the nucleus! What force balances that attractive force? ...
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0answers
22 views

visualizing an atom [duplicate]

If we could fix our minds eye within the vast empty space encompassed by the orbiting electron(s), would the nucleus have a discernible volume and shape? Would all nuclei be similar just different in ...
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1answer
25 views

Magnetic field in the ground state of hydrogen

What is the magnitude of the B field produced by the electron's orbital motion in H1, according to classical model? I found all sorts of values, I myself calculated 1/8 T, using the standard formula, ...
6
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1answer
76 views

How does a lever magnify force? [duplicate]

I understand that energy is conserved when a force is applied to the end of a lever and magnified closer to the pivot point. However, I would like to know how it is the force is transferred and ...
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3answers
111 views

Why does a “typical” hydrogen atom have no neutron?

There are quite a few sources (mostly high-school physics textbooks) that I've read which don't give the disclaimer that the hydrogen atom they are using in a diagram is an isotope (as in having ...
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1answer
1k 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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2answers
415 views

Resonate frequency of an object?

Below is a paragraph taken from the web site, physicsclassroom.com: It is often useful to think of these electrons as being attached to the atoms by springs. The electrons and their attached ...
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3answers
85 views

Why can't electrons absorb any energy (i.e. absorb some energy of the photons necessary and emit the residual)?

Recently I had a question in mind about the absorption of photons. Why is it that only specific energy levels can be absorbed by electrons? I mean, I get the idea that electrons in an atom have only ...
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1answer
50 views

In an infinite universe, would there be an infinite amount of matter as well?

Or would you eventually reach a point past which there is no matter? How would an infinite amount of matter work? Would it sort of "loop back" to the beginning, or would it be entirely unique the ...
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2answers
55 views

Atom Particles Relationships

I am an agriculture student, and we study tons of chemistry, and despite I took the exams I still have a good doubt on atoms. Through my studies I would say electrons are very tiny containers of ...
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2answers
76 views

Why does gravity have such an insignificant effect on particles at an atomic scale?

E.g. why do we experience gravity all the time, but on an atomic scale, the gravitational forces are so small?
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0answers
29 views

Space expanding within atoms [duplicate]

I'm hoping that "all questions are good questions." I'm a layman enthusiastically trying to comprehend cosmology and physics, and the more I learn the more questions I have. My understanding is that ...
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2answers
82 views

The calculation of the entropy of a single atom

I used to think that the entropy of a single atom could not be calculated, for in my mind only the entropy of a system containing many atoms could be calculated. But my professor told me the entropy ...
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0answers
28 views

Interaction of atoms of the same material

So I've been reading a section about energy levels and came across this statement: "As the atoms of a material are brought closer together to form the crystal lattice structure, there is an ...
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2answers
220 views

My book uses helium weight in reaction formula instead of weight alpha particle?

I'm suppose to write out reactions where atoms send out alpha radiation and decay. The book uses the 4-2 H, 4 as nucleon number and 2 as proton number, but isn't that wrong? The mass of helium is ...
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0answers
19 views

Could artificial atoms not based on quantum dots be created at a similiar size to natural atoms

I'm aware of current pace of quantum dot technology so I am aware they are not close to the smaller size of natural atoms of known elements so I wondered if it's theoretically possible to achieve this ...
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5answers
2k views

What really is the smallest “mass” or “object” in the universe?

As the Wikipedia article Subatomic particles shows, with respect to the sciences, the atom is obviously not the smallest piece of mass. Apparently, if people have already broken down the atom in to ...
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0answers
18 views

Thomas-Fermi energy level

Following Hitoshi's notes on the Thomas-Fermi levels (http://hitoshi.berkeley.edu/221B/atomic.pdf) i was able to solve for the potential $\phi(r)$ for the Al$^+$ ion. Now I want to solve for the ...
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0answers
11 views

Surface potential and symmetry breaking

I am studying surface states currently and am a little confused about something. If I consider p-orbits on a surface state that is the top layer of an HCP structure -- I understand the hopping terms ...
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1answer
5k views

Why do the radii decrease when we move left to right in the periodic table?

The explanation that I have heard states that when we move horizontally across the periodic table, the number of electrons increases leading to a greater force of attraction from the nucleus. For ...
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1answer
31 views

Why the properties of a substance like color changes when we go into the nano scale?

I have heard that the physical as well as chemical properties of a substance changes when we go to the nano scale. For example, Gold is considered an inert material in that it doesn’t corrode or ...
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1answer
39 views

Atomic radii for elements as hard spheres

In neutron scattering, the atoms in a system are considered as hard spheres. Where could I find the appropriate (reliable) values of the atomic radii consistent with this physical picture? Thank you ...
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1answer
133 views

why is it that the photon incident on metastable state stimulates atom to go into ground state but not to even higher energy state?

isnt it possible that photon incident on atoms at metastable state goes to further high energy state rather than the ground state? whilist there is always that stimulated emisson taking place. why ?
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3answers
64 views

Can electrons emit light when they are independent? [duplicate]

If an electron is independent, it is an individual electron, i.e. not in the orbit of the atom. Is it able to emit light or does the orbit have to do with the production of light?
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1answer
1k views

Nanotech - zero dimensional fullerene

Not really a physics junkie, and I think this is a chemistry question, but since there's no chemistry.stackexchange.com (yet) I think here is the best place. I was just reading up on nanotech and ...
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0answers
31 views

Estimate the threshold for $e^+e^-$ production due to the vacuum instability in an atom.

When a nucleus with very high $Z$ is created, the binding energy of the innermost electronic orbit becomes sufficient to create $e^+e^-$ pairs. The pair can be created out of the vacuum – the electron ...
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2answers
6k views

How many atoms are there in our solar system?

Including all objects gravitationally bound to the Sun, how many atoms are there in our solar system?
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1answer
652 views

Atomic gravitational field?

This might be a silly question, but if every atom has its own gravitational force could atoms or molecules be attracted to each other over vast distances in the void of space if there were no other ...
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2answers
67 views

How can only one valence electron in sodium cause doublet in spectrum?

The valence electron in sodium atom gets excited and moves to higher orbital say $3P$ and it then comes to the lower energy state $3S$ thus there should be only one line in spectrum (regarding this ...
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1answer
53 views

The Space Between Atoms And Sub-Atomic Particles And More [closed]

I was wondering what the space between atoms or electrons is called. Is it Vacuum ? And what is in there ? Is it really free or empty space ? And if so, how can nothing exist ? It is a bit of an odd ...
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3answers
6k views

Photon hitting an atom with higher energy than needed to ionize

Suppose we have an atom with several energy levels (e.g. an hydrogen), and it is hit by photons. I know that in order to have the atom change energy levels, the photon must have an energy level ...
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8answers
10k views

Why does space expansion not expand matter?

I have looked at other questions on this site (e.g. "why does space expansion affect matter") but can't find the answer I am looking for. So here is my question: One often hears talk of space ...
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0answers
12 views

In non-metallic solids w/ just atoms or ions (no molecules), are bonds (vibrations) and electronic transitions the sole cause of blackbody radiation?

Since there wouldn't be a conduction band filled with any electrons in a non-metallic solid made of just atoms or ions (no molecules), it's hard to imagine any other type of movement and dipole moment ...
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1answer
48 views

Hydrogen in a glass of water

One of the great Sagan quotes is that we are made of star stuff - meaning the atoms in our bodies were formed from stellar nucleosynthesis. However, what about the hydrogen in a glass of water? Would ...
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5answers
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How can the nucleus of an atom be in an excited state?

An example of the nucleus of an atom being in an excited state is the Hoyle State, which was a theory devised by the Astronomer Fred Hoyle to help describe the vast quantities of carbon-12 present in ...
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1answer
42 views

Does Rydberg's formula work for different orbitals?

Rydberg's formula is given as $\frac { 1 }{ \lambda } =R\left( \frac { 1 }{ { { n }_{ 1 }^{ 2 } } } -\frac { 1 }{ { { n }_{ 2 }^{ 2 } } } \right) $ where ${ n }_{ 2 }$ and ${ n }_{ 1 }$ are the ...
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1answer
28 views

In Rayleigh scattering, does a light wave cause the electrons (themselves), in a particle, to move at the same frequency as the incoming light?

The excerpt below, about Rayleigh scattering, is taken from the following page: https://en.m.wikipedia.org/wiki/Rayleigh_scattering Rayleigh scattering results from the electric polarizability of ...
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0answers
42 views

How many atoms do we need to store a bit?

And which kind of storage (HDD, flash, blue-ray, etc) has the most efficient atoms/bit ratio?
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1answer
43 views

Number of photoelectrons vs Frequency

This is the graph plotted between photocurrent (proportional to number of photoelectrons) and potential applied with different frequencies. As it can be seen, the number of photoelectrons released ...
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2answers
548 views

How are anti-matter atoms created?

What is the reaction, or reactions that make anti-matter? I don't understand how anti-matter is created by CERN if interaction with normal matter causes annihilation.