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

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40 views

Why is the melting point of an object inversly proportional to pressure?

In my science book it is written that as the pressure increases the melting point of a solid decreases but i think that it is wrong as the pessure will make the molecules stick together instead of ...
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1answer
43 views

Classical Hydrogen Atom

I was wondering about the Hamiltonian description of the classical hydrogen atom (two point particles interacting through a Coulumb potential). In particular, I want to know if the fact that ...
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0answers
27 views

What happens when you use an electric field to match atom oscillations?

I've been thinking about this question for the last few days: "What happens when you either use an electric field or sound / light to match the frequency of the atomic lattice?" What would happen to ...
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0answers
33 views

Why doesn't a nuclear reactor's filament deform?

Why doesn't a nuclear reactor's filament deform? The filament in the core of a nuclear reactor is usually made of uranium rods. So in the nuclear reactions the neutrons constantly move from filament ...
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1answer
63 views

How much am I floating above the chair I am sitting on? [duplicate]

The electrostatic repulsion between me and the chair keeps me hovering above the chair at all times. What is the average distance that exists between any two everyday object due to electrostatic ...
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2answers
59 views

Bohr/De Broglie simplfied model - joining orbitals

I understand that Quantum Mechanics has taken over and fully explains this but I'm struggling to understand in terms of the old model. Bohr's model as modified by de Broglie suggested that orbits ...
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1answer
50 views

If we hit an electron will it go to an excited state?

For example i have a block of silicon doped with phosphorous and i hit it hard with a hammer will the energy get transfered to the block and make the electrons excited?
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1answer
19 views

How can silicon have a capacity of 8 electrons in the outer shell?

I was reading an article on how solar cells work in this website- http://science.howstuffworks.com/environmental/energy/solar-cell2.htm In that website I have a doubt in the first paragraph i.e.- ...
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1answer
23 views

Whats the maximum number of electrons that can fit into the outer shell of boron?

Whats the maximum number of electrons that can fit into the outer shell of boron? Like silicon has 4 electrons in the outer shell but the maximum it can hold is 8 electrons so whats the maximum number ...
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0answers
35 views

mirror nuclei: accounting for the difference in mass between nuclei

I was wondering if anyone here could guide me in the right direction with respect to the following problem: two nuclei are considered mirror nuclei if interchanging the neutrons and protons turns one ...
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2answers
55 views

Atoms in a piece of paper?

How many atoms are there in a common paper sheet? I mean, for example, in one of those we use for photocopies, numerically speaking, how many atoms in total? (Ten to the power of..?) And I'd like to ...
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0answers
23 views

What are the reactions that take place inside battery at the quantum level?

I was just studying about how a battery works on the internet and found out that there are reactions of chemicals which make the electrons move. But what exactly happens inside a battery (lets take a ...
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3answers
5k views

Is it possible that every single isotope is radioactive, and isotopes which we call stable are actually unstable but have an extremely long half-life?

I've read that tellurium-128 has an half-life of $2.2 \times 10^{24}$ years, much bigger than the age of the universe. So I've thought that maybe every single isotope of every single atom are ...
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1answer
50 views

Can an Atom be negatively as well as positively charged simultaneously?

For example there are three atoms- atom A, atom B, atom C. Atom A has 3 electrons, atom B has 4 electrons and atom C has 2 electrons. If we bring together atom A and atom B, in this case atom A is ...
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1answer
47 views

What are these wavish patterns around atoms on microscopic images?

This is an IBM movie about how they move single atoms: http://www.youtube.com/watch?v=oSCX78-8-q0 There are often some "wavish" pattern around atoms on these pictures, like below some of them marked ...
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2answers
42 views

How do atoms in a solid “communicate” force to each other?

What is the mechanism that carries and communicates force in a solid, on the atomic level? Is there some other mechanism besides atomic deformation and proximity? That is, if I had an infinitely ...
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1answer
42 views

Electricity should deform the conductor then why doesn't it?

In electric current both negative particles and positive particles flow but in opposite directions. So why doesn't the conductor's shape deform because its particles are moving here and there? OR is ...
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0answers
38 views

Do the norms of the total and the orbital angular momentums commute? If yes, why is there a problem with 2p_{1/2}?

Question: For $\vec L$ the orbital angular momentum of an electron, $\bar S$ its spin, and $\vec J:=\vec L+\vec S$ the sum, do $\vec J^2$ and $\vec L^2$ commute? I assume it does: $[\vec J^2,\vec ...
2
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1answer
84 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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3answers
60 views

How nuclear fission works in power plants? [closed]

As per the laws we are not able to see atoms (atom is microscopic). Then how does the nuclear fission works? *. In nuclear fission, splitting atoms is a exact calculation or probability(like we 1 ...
3
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1answer
44 views

If we cut an object in half and touch the two halves together, why do the bonds not reform automatically?

A friend recently posed this question to me: let us take an arbitrary object and cut it into two pieces (not necessarily equal in any way). If we touch the two pieces back together so the object ...
46
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1answer
4k views

Is it possible to “see” atoms?

As per my knowledge, atoms are small beyond our imaginations. But there is an image on Wikipedia that shows silicon atoms observed at the surface of silicon carbide crystals. The image: How can we ...
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1answer
140 views

Do electron shells exist within equipotential regions?

I had to read up on equipotential surfaces recently and I noticed the pattern of equipotential surfaces around a point charge. The idea came to me then that since no work is done in moving charges ...
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1answer
100 views

Electricity is the movement of electrons or ions?

Electricity is the movement of electrons from one atom to another or the movement of charged negative particles (ions)?
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0answers
29 views

What exactly is cutting with a knife will look like on the atomic scale? [duplicate]

Some times I like to view the world in the microscopic scale .ie. at this level all objects any thing will be collection of atoms which we normally don't view with our naked eye. At that scale I ...
4
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1answer
60 views

How can absorption spectra form if atoms can't remain in an excited state?

I have been tasked to write a research paper on stars. However, I know very little about physics in general. I am learning about how we can glean information about stars by analyzing the light that ...
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2answers
161 views

Why are atoms of the same element exactly the same?

Based on what we know about atomic structure all atoms have an electron density function which describes the uncertainty in the position of an electron. Thus theoretically 2 atoms of the same element ...
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1answer
31 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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1answer
82 views

Where does the energy within atoms come from?

Most kinds of energy I know about involve a finite measurement and are transferred. In other words, energy in the universe is finite and is not lost or gained but only transferred through space one ...
2
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1answer
83 views

In atoms, what is potential energy?

I was reading about how potential energy in atoms is measured by how far apart they are from one another. From what I have heard of potential energy, it's a way of showing how fast an object could ...
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1answer
119 views

What is the most accurate experimental confirmation of Rutherford's $\sin^{-4}\phi/2$ law?

What is the most accurate experimental confirmation to date of Rutherford's $\sin^{-4}\phi/2$ law, where $\phi$ is the scattering angle?
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5answers
4k views

What enables protons to give new properties to an atom every time one is added?

How does adding one more particle to the nucleus of an atom give that atom new properties? I can see how it changes it's mass, that's obvious... But how does it give that new atom different properties ...
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1answer
97 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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2answers
1k views

Do we really not know why atoms 'decide' to produce a photon?

I was watching the Cosmos documentary where Neil deGrasse Tyson explained how certain energy photons get absorbed by an atom, which causes the electrons of that atom to climb into a higher energy ...
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0answers
37 views

What properties affect the color of item?

I already understand how gap bands work and how atoms can absorb/reflect light. I also already understand that rough objects will reflect light differently in comparison to smooth objects, but I do ...
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1answer
51 views

One color frequency items

I asked a slightly different question before, but how common are one color frequency items? Many things can reflect many colors of light, but predominantly show one under white light. If they are ...
3
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1answer
66 views

Why are some elemental materials grey?

How does grey occur in elemental materials such as metals? I believe that grey arises from the simultaneous reflection and absorption of all colors of the spectrum (in different atoms of course), as ...
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1answer
33 views

Reflections of objects of a particular color

How can any color reflect the color of light shone upon it? I tested this by shining different colors of light on different objects, and instead of becoming black, it reflected a hazier form of that ...
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2answers
58 views

The Color White

How can something that is white reflect all colors? It would have to reflect all frequencies or at least blue green and red, correct? How can a two element compound, such as NaCl reflect all of these ...
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1answer
103 views

How can we prove that the shape of atom is spherical? [closed]

i am looking for a derivation that can prove that the shape of an atom is spherical . I experimentally proved this statement but i need a theoretical way.
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2answers
949 views

Why is Graphene Transparent?

Graphene is always in the news now a days and its key features are that it is; very strong, conductive and transparent. It is so transparent that each layer of graphene will only absorb 2% of Light ...
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2answers
99 views

Why is Graphene So Strong?

There has been a lot of news about Graphene since its discovery in 2004. And as we are all told it is a revolutionary material which is very strong, conductive and transparent. But what is it about ...
0
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1answer
36 views

photon absorption and emission

I was reading a book (Sears Zemansky) about this subject but I didn't understand something of an example, and this is that according to me there should be a process of emission for each of absorption ...
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2answers
101 views

Why are atoms empty so much?

To clarify: My question is not Why are atoms empty?, my question is Why are they empty so much? The classical orbit of an atom, roundly speaking, is where the probability to find an electron is ...
4
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1answer
102 views

How are atoms entangled, and can it be done remotely?

First of all, how exactly do you entangle two atoms? I've heard about how they entangled atoms in quantum Teleportation experiments, but I don't get how they did it. I've heard that the atoms must ...
0
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3answers
83 views

Do electrons get accelerated or decelerated by the atoms of the anode during X-rays production?

The electrons striking the anode get deflected by the heavy nucleus. Though the speed may or may not change, the direction of motion changes which leads to acceleration. The charged particles emit ...
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1answer
90 views

Is charge transfer from A to B positive or negative?

I see this term pop up a lot -- for instance "charge is transferred from atom A to atom B", but it's never specified whether they're talking about positive or negative charge. I know electrical ...
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0answers
21 views

Photon absorption by a hydrogen atom : [duplicate]

How does the photon absorption takes place in a hydrogen? The classical mechanics shows the absorption of photonic energy resulting in the excitation of atom. Intuitively, a photon with frequency ...
4
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1answer
94 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 ...
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0answers
162 views

How to calculate the $g$ degeneracy factor for alkali metals and their singly ionized species?

The Saha ionization equation is $$\frac{n(X_{i+1})}{n(X_{i})} = \frac{(2\pi m k T)^{1.5}}{n_e h^3}\frac{2g_{i+1}}{g_{i}}e^{-\chi/kT}$$ where $\chi$ is the energy difference between the two ...