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

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43 views

Interpretation of TEM pictures of atoms

I've got a question about images taken with Transmission Electronic Microscope. Are the images we find on scientific papers and articles on the web the negative of the real image appearing on the ...
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0answers
25 views

Emptiness of the atom [duplicate]

If the atom is actually 99.99% empty, why can't we just put our hands or things inside them?
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0answers
39 views

Can a quark be changed to a different flavour?

For example, is it possible to change an up quark into a down quark or vice versa? If so, what is the practical process for doing such a thing? What is the theory behind it? For an example, lets say ...
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2answers
37 views

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 ...
6
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7answers
2k views

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

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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0answers
10 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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1answer
55 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 ...
4
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1answer
100 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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2answers
403 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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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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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 ...
1
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1answer
28 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
83 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 ...
4
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3answers
124 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
51 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 ...
4
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3answers
87 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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2answers
57 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
81 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 ...
6
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2answers
83 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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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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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
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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3answers
76 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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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
76 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
56 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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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 ...
3
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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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1answer
44 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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47 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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0answers
49 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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1answer
92 views

vibrational motion in gases

In a debate, I argued that vibrational atomic movement as cause of internal energy is prominent in solids (due to their crystal structure) and it is not prominent in gases. I think this also applies ...
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1answer
67 views

Can electrons within a positive ion absorb and reflect light?

I understand that in a crystalline metallic structure, such as one making up a bar of gold, there are one, or more, valance electrons of each atom that have left their outer shell (became free ...
2
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2answers
114 views

Element 137 - Theoretical limit [duplicate]

I've seen a few sources that mention the speed of an electron in a hydrogen atom is 1/137 the speed of light. This article also mentions what looks like a correlation between atomic number and the ...
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0answers
20 views

Does an electron's energy decrease while performing its motion? [duplicate]

While revolving around the nucleus if the electron's energy decreases then will it hit the nucleus and if it does what will happen?
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4answers
146 views

What is meant by an excited atom?

I want to know how an atom is when it is excited. If an atom, due to collision of another fast moving atom, becomes fast moving as well, is that also an "excited state"?
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1answer
138 views

Atoms, Gravity and Electrostatic Charge [closed]

How close do 2 atoms of any type the have can be together before gravity with an electrostatic charge that repulses?
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1answer
67 views

Earnshaw's Theorem and Plum Pudding

I'm trying to understand what Thompson's motivation for his Plum-pudding model was. He chose the nucleus to be a sphere of uniform charge because it was mathematically nice, and chose the charge to be ...
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1answer
36 views

How does conduction happen?

I'd like to ask you how does conduction happen ? I mean, the atoms vibrating more hits the less vibrating atoms and gives energy. But how is that energy transferred ? For atoms to collide they must be ...
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3answers
114 views

Can atoms lose electrons by themselves?

I know atoms lose or gain electrons through ionic bonding but when they are by themselves do they lose electrons? I read in a book on metallic bonding which involves free electrons(the lost ones) and ...
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1answer
47 views

The atomic mass of an isotope from atomic weight

I'm reading for an entrance exam and have a practice question about the atomic mass of an isotope that I have to figure out. I am given the atomic weight of the element. How can I calculate the ...
2
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1answer
56 views

Is it possible to view an atom? [duplicate]

Is it possible to view an atom? What would it look like? Would it resemble a traditional atomic diagram?
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2answers
137 views

Why doesn't silicon emit light? [closed]

Why doesn't silicon re-emit light when light falls on it? Or if it emits light then why we can't see it?Hence it has valence electrons.
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1answer
31 views

Gasses and Gravity

I have two questions. First question. When gas is placed inside a container it fills the container evenly with constant pressure. If the container size varies the gas expands or is compressed but the ...
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1answer
45 views

Why insulators do not conduct electicity when they are negatively charged?

The following excerpt is from Young and Freedman 13th edition: Most metals are good conductors, while most nonmetals are insulators. Within a solid metal such as copper, one or more outer ...