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

learn more… | top users | synonyms

1
vote
2answers
61 views

Does the doppler shift have any effect on the energy that the atom absorbs?

Does an atom moving towards the light that is falling on it, absorb more energy than when it is stationary? The atom should a see blue shift due to Doppler effect so the atom will see a light of ...
6
votes
3answers
5k views

Why do electrons in an atom 'fall' back to the ground state?

Why, after absorbing a photon does an atom's electron 'fall' back to its ground state (what causes it to immediately lose its absorbed energy)?
0
votes
2answers
282 views

Mathematical description of electron configuration

Does there exist a mathematical model for determining the electron configuration of an atom? I mean the theory which would generalize the notion behind the informal elements of the Aufbau principle.
-3
votes
1answer
3k views

Have we ever seen an atom? If not, how do we know they exists? [duplicate]

Question is what exactly title says that have we ever seen an atom through any means (microscopes/equipments.etc)? If not, how do we know they exists?
0
votes
3answers
136 views

Which particles can go right through the atom?

Can elementary particles (like the electron, photon, or neutrino ) go through an atom (not the nucleus)?
1
vote
5answers
1k views

Can we squeeze atoms?

Lets consider few water molecules (or monoatomic noble gas or $H^+$ ions or electron gas) to be present inside a vessel, now if we enclose the vessel with certain hard material which could act as ...
2
votes
3answers
840 views

Do atoms of a surface excite to reflect the light?

How do surfaces reflect certain colours and absorb the others?
-2
votes
1answer
119 views

Angular momentum Bohr's model

I have been trying to derive speed, radius etc. in hydrogen atom using Bohr's postulates and not neglecting the coulombic attraction on proton. I know that they will be revolving around their centre ...
1
vote
1answer
233 views

How much smaller will be human body, when we hypothetically get of every space between particles [closed]

I had an interesting dream, where advanced civilization compress their body with technology, that turn off space betweens atoms/particles. They travel in small spaceship with billions citizens very ...
0
votes
3answers
138 views

In what form does proton give energy to electron?

According to Bohr, electron revolves around the nucleus because of force of attraction between electron and proton. This force of attraction gives energy to the electron. So my question is this that- ...
2
votes
1answer
138 views

Atomic transitions and density: clarification

A laser passes though a cell containing vapor of an alkaline element which causes atomic transitions. I was told that the formula for the atomic density in a Rubidium cell, for example, is given by: ...
6
votes
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.
1
vote
0answers
39 views

An EM problem of polarized sphere

Today, I'm doing an EM problem and my question is exactly the same as this site shows: http://www.physicsforums.com/showthread.php?t=133501 To reiterate my confusion, why we can't use that integral ...
0
votes
2answers
793 views

question on dipole moment of water molecule

I read a line today and don't get it: "Molecules with mirror symmetry like oxygen, nitrogen, carbon dioxide, and carbon tetrachloride have no permanent dipole moments." http://hyperphysics.phy-astr....
0
votes
0answers
29 views

Rutherfords alpha scattering conclutions? [duplicate]

Please can some one give me rutherfords observations and his conclutions from each onbservation, I have looked in text books but they only give them sepratly with no direct link betweeen which ...
1
vote
1answer
449 views

Hydrogen ionization energy [closed]

Proton and electron have a distance equal to the Bohr radius apart in the hydrogen atom. Knowing this, what's the ionization energy of the atom? So we know $U = -kq^2/a_B$, but this is potential ...
2
votes
1answer
306 views

The position of center of mass of electron cloud in an atom

I read Griffiths EM today and it says something very interesting but a little bothering to me. It states for an atom, the position of center of mass of an electron cloud lies in the center of the ...
2
votes
1answer
151 views

Smallest possible object made of atoms that is spherical to a given degree [closed]

I recently saw a video, World's Roundest Object, which discussed a sphere made of silicon-28. The researcher in the video stated, if the object was scaled to the size of the Earth, the highest and ...
0
votes
1answer
428 views

Expectation value of energy from the position state of hydrogen atom [closed]

I was given with the position state of hydrogen atom: $$ R_{21} =\left(\sqrt{\frac{1}{3}}Y^0_1 + \sqrt{\frac{2}{3}}Y^1_1\right) $$ I am getting confused about getting the expectation value of energy,...
0
votes
1answer
6k views

Why electrons get excited? [closed]

Why and how are electrons get excited and what happen inside an atom when electrons get excited?
1
vote
2answers
96 views

Quarks are now considered to be fundamentals, but so were atoms some time ago. So the way we see is only limited by our technological advances? [duplicate]

After watching this FuseSchool - Global Education episode, I cannot stop thinking how can something not have a substructure, how it cannot be split? http://www.youtube.com/watch?v=nlv06lSAC7c
0
votes
1answer
197 views

How do magnetic objects exhibit attraction/repulsion across empty space?

Magnets will attract or repel over a distance before physically touching each other. What makes this effect possible? My best guess is that the forces generated by the angular momentum of the ...
4
votes
2answers
210 views

Electron speed in Atoms

Is the speed of electrons in Atoms consistent in all Atoms or clusters/groups/individual elements, and if it is consistent in any atom, is that speed constant?
0
votes
2answers
276 views

Are particles solid?

My intuitive understanding is that although atoms are mostly empty space, the nucleus is solid. Thus a neutron or a neutrino can collide with it and do things like deflect or cause a nuclear reaction....
1
vote
0answers
27 views

How does beta+ decay actually occur? [duplicate]

I'm having difficulty in understanding beta plus decay. How can a proton which has slightly less mass than neutron transform into a neutron, positron and neutrino? Form where does the extra mass for ...
3
votes
1answer
220 views

Do atomic nuclei have fixed orientation and position with respect to the electron cloud?

Does the nucleus of an atom of any element (besides protium) maintain a particular orientation in relation to its electron cloud? Does it bounce around within its cloud? Can it be ejected from its ...
2
votes
0answers
50 views

Cathode Ray Tube

I am considering the cathode ray tube of the set up, when the cathode rays were discovered Voltage = Very High Gas = any Atmospheric Pressure = We change (In the following example i am just changing ...
4
votes
2answers
475 views

Hydrogen atom: potential well and orbit radii

I happened to open up an old solid-state electronics book by Sah, and in it he says: "it is evident that the electron orbit radius is half the well radius at the energy level En" The orbit radius is ...
1
vote
2answers
74 views

Molecules and electrons energy types

What are the types of energy that an atom or a molecule could have? For example they have kinetic energy, could they also have other types?
2
votes
2answers
105 views

How do you know which atoms are in a specific piece of matter?

If you have a piece of matter in front of you, how can you know of which atoms it consists? And starting from nothing, how can I discover all the elements (or just a lot of them) of the periodic table?...
34
votes
4answers
5k views

Are atoms unique?

Do atoms have any uniquely identifying characteristic besides their history? For example, if we had detailed information about a specific carbon atom from one of Planck's fingerprints, and could time-...
1
vote
0answers
919 views

Show that the circumference of the Bohr orbit of hydrogen is an integral multiple of the wavelength of the electron in it [closed]

We have an electron revolving in a the $n$th Bohr orbit of an atom of hydrogen. The problem is to prove that the circumference of the orbit is an integral multiple of wavelength of this electron $\...
3
votes
0answers
139 views

What are the assumptions behind “term symbols”?

In multi-electron atoms, the electronic state of the optically active "subshell" is often expressed in "term symbols" notation. I.e. $^{2S+1}L_J$. This presumes that the system of electrons has ...
0
votes
2answers
258 views

What happens to the atoms and their constituents when we break something ?

My query is: how does an atom stable itself. When we break something, what actually happens in the chemical bonding of its atoms, does it rupture or remain intact?
0
votes
1answer
2k views

Why is the charge on protons == to charge on electrons? [duplicate]

I am not a expert on physics, just another high schooler, so sorry if the question is obvious. This is something I've been wondering about for a while. Why is the charge on a proton equal but ...
4
votes
4answers
167 views

Are atoms getting weaker? [duplicate]

If the universe is expanding, it would make sense that the spaces between particles are getting bigger. If this is so, then the particles which make up atoms are also affected. Does that imply the ...
2
votes
1answer
64 views

Can there exist a Wave which changes the quantum states of particles?

i'm a high school student and i was reading about electromagnetic waves and how they transport energy and that the electric and magnetic fields sustain each other. I have also read about longitudinal ...
2
votes
2answers
589 views

What is the reason for the electrons in a given subshell to orient in certain preferred regions?

My text book says: "Magnetic quantum number describes the behavior of electron in a magnetic field. We know that the movement of electrical charge is always associated with magnetic field. Since the ...
4
votes
2answers
6k views

Why do atoms stick together?

The atoms in my table "stick together" to form a rectangle. Why? What makes them stick together? I know about ionic/covalent bonding etc., but consider a sheet of pure iron. Just atoms of one element....
0
votes
3answers
317 views

Atoms and electrons?

Consider a copper atom. If you place an electron near it, the protons in the nucleus would attract it like they attract the existing electron in the valence shell. However the electron you placed ...
2
votes
1answer
2k views

Is it that electron of an atom can be found anywhere in the space?

Simple pictures showing orbital shapes are intended to describe the angular forms of regions in space where the electrons occupying the orbital are likely to be found. The diagrams cannot, however,...
0
votes
1answer
61 views

Is there a probability that an electron in an atom change its energy level due to emitting gravitational wave?

Is there a probability that an electron in an atom change its orbital by emitting a quantum of gravitational radiation instead of photon?
7
votes
3answers
939 views

Why is a proton assumed to be always at the center while applying the Schrödinger equation?

Why is a proton assumed to be always at the center while applying the Schrödinger equation? Isn't it a quantum particle?
0
votes
2answers
2k views

Why would an electron in an orbit be accelerating continuously and would thus radiate away its energy and fall into the nucleus in a classical model? [duplicate]

I was reading this answer by madame anna v: You are right, the planetary model of the atom does not make sense when one considers the electromagnetic forces involved. The electron in an orbit is ...
3
votes
1answer
49 views

Measuring spin direction by means of coherent light?

Let us assume that we have the ferromagnetic surface where all atoms have the same direction of spins. And we can interact with the single atom in such lattice. Is it possible to measure the ...
3
votes
4answers
1k views

How to determine what an object is composed of?

Heads up: This question has never been asked (here) before the way I will ask it here, so let's shed some light on it a bit. Prelude and anecdote(can be skipped): The other day I was walking home, ...
0
votes
1answer
245 views

Electron Decay, Why are there P and higher orbitals?

Related: Decay from excited state to ground state My confusion arose initially from the definition of binding energy being the lowest energy state (n=1) in the hydrogen atom. This, I assume, is ...
0
votes
5answers
2k views

Do electrons collapse into nucleus, if electrons in the atom are constantly excited?

From the Bohr's atomic model, it is clear that electron can have only certain definite energy levels. When the electron is present as close to the nucleus as possible, the atom has the minimum ...
1
vote
4answers
1k views

Why is the Bohr's idea of defined circular orbits overruled?

If we consider a thought experiment for determining position of an electron by using photons of light. According to principles of optics, if we use light of wavelength $\lambda$, then the position of ...
0
votes
1answer
7k views

How can I calculate out the 'specific charge' of an atom? [closed]

I know that it's charge/mass. But what steps do I take to calculate the specific charge of say, carbon-12? What about ions too?