Questions tagged [atoms]

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

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Collision of $\rm H$ atoms [closed]

The question is: Two $\rm H$ atoms in the ground state collide inelastically. The maximum amount by which their combined kinetic energy is reduced by__________ well in this question I solved it ...
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About why electrons in atom don't radiate(considering wave nature also) [duplicate]

It's said in textbooks that electrons won't radiate and fall into nucleus because matter wave of it's form a standing wave but could somebody explain why being a standing wave it doesn't radiate, even ...
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How many states are possible for two (indistinguishable) electrons with $n=2$ in an atom if we forget Pauli’s exclusion principle?

I have been told I can use $^8C_2 = 28$ to obtain the answer to this question, but I am doubtful of this result since I obtain $21$ by simply writing out the possible states as ($ml_{1}$, $ms_{1}$, $...
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How does removing air from a vessel of water create bubbles?

I recently started reading Richard Feynmans 'six easy pieces'. I did physics and chemistry combined in secondary school but that was 3 years ago and thought it would be a nice introduction back into ...
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Relativistic Corrections to the Binding Energy of Atoms

The binding energy of atoms is the minimum energy required to remove an electron of an atom from its orbital. Using dimensional analysis, we can derive the following equation. $$E_B\propto\frac{m(ke^2)...
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What is the function of the RF pulse in NMR?

I am slightly confused about the purpose of the RF (radiofrequency) pulse in NMR. The powerpoint of my course mentioned that an RF pulse perturbs the equilibrium magnetization and sets the nucleus ...
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Why don't electrons fall or collapse around atom when an object accelerates rapidly?

In laws of motion, everything has an equal and opposite reaction, and it applies to all matters in the reality. If the earth stops moving suddenly just for one second, then everything on earth will be ...
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Nuclear energy and Nuclear fission

It is mentioned that the lesser the total mass of the nuclei, greater would be the binding energy per nucleon. I do not seem to understand this.. As per my understanding of binding energy, it is the ...
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Is the motion of an electron bound into an atom inertial?

When a particle moves on a gravitational potential subject to no contact and tidal forces, the particule clearly is in inertial movement. But what about the "motion" of an electron bound ...
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Are there any different ways to theorise that atoms exist?

I have read that Albert Einstein and some notable others theoretically proved atoms through Brownian motion. Are there any other perspectives or methods to theoretically or experimentally prove that ...
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About normal Zeeman effect and Hydrogen atom

I think that the normal Zeeman effect is experimentally observed only when we can neglect the spin i.e. if we consider a spin-singlet state with total spin $S=0$. Since in the hydrogen atom there is ...
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Forces between electron, neutron and proton

What are the forces between a proton and another proton? I think they are electromagnetic, gravitational and nuclear. Forces between proton and electron? I think, electromagnetic, gravitational and ...
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Attraction power of london dispersion forces

London dispersion forces are forces of attraction between atoms or non polar molecules (Despite they have symmetrical distribution of electrons in it). It's mentioned in my book that london dispersion ...
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Do individual atoms have any semblance of rotation (aka yaw, pitch, rol)?

When describing a static 3d object in 3d space, we often use 6 numbers: x, y, z coordinates of one of objects points and yaw, pitch, rol for objects rotation. Do individual atoms have any semblence of ...
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Why does aluminium lose its three valence electrons when the electron pair have opposite spins?

Why does aluminium lose its three valence electrons when the electron pair have opposite spins? Why do metals generally lose electrons completely instead of attaining pairs of electrons with opposite ...
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Selection rules for atoms

I was told that in atoms the transitions between the energy levels are restricted by so called selection rules. For example if $J$ (resp. $J'$) denotes the (angular plus spin) momentum of the atom ...
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Is that electron which jumps from one stationary state to another?

In classical physics book of Kleppner, I read that An atom can "jump" from one stationary state a to a lower b by emitting radiation with $E_a-E_b$. The frequency of the emitted "...
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Separable Hamiltonian systems in quantum mechanics

Why is it that in separable Hamiltonian problems the total eigenfunction is equal to the product of the individual eigenfunctions, but the individual Hamiltonians must commute? In mathematics, when ...
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To which orbital does an excited electron in a hydrogen atom go?

For atoms other than hydrogen, each subshell within an energy level has distinct energy. For hydrogen, however, all orbitals within an energy level are degenerate (have the same energy). So, when the ...
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Is gravity the result of protons and electrons? [closed]

I understand that gravity is the result of a curved space/time caused by mass. But is it possible that gravity is the result of protons and electrons magneticly interacting on a massive scale? Large ...
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What is the difference between band gap and first ionisation energy?

To me both the band gap and first ionisation energy seems to be the same thing as both are the energy required to remove the valence electron from the atom. So I am confused whether they b are the ...
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Can Wavelength also be used as Circumference?

Could Lights wavelength be the result of the electron orbits and its distance? Could this be why wavelength and orbit circumference measurements are the same? This would imply that wavelength radius ...
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How come the number of wandering electrons is same as the number of the positive ions?

My book mentions the following: Cause of resistance : When an ion of a metal is formed , its atoms lose electrons from its outer orbit . A metal ( or conductor ) has a large number of wandering ...
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Do noble gases attract each other?

When 2 atoms come close enough, the nucleus and the electron cloud attract each other, the electron clouds are pulled between the the nuclei's until an equilibrium distance is reached. Why doesn't ...
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What is currently the most accurate visual depiction of the atom? What does an atom look like so far as we know?

During my undergrad studies, I am constantly told how Bohr's image is wrong, for example, and how all my pre-notions of an atom are bad. Still, I've never been shown what the accepted contemporary ...
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Stern Gerlach experiment vs Zeeman effect

In the Stern-Gerlach experiment, we discover that electrons have an intrinsic angular momentum, that we happen to call "spin". They applied a magnetic field to a source of atoms (originally, ...
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Binding energies for muonic atoms - database

Does exist a database reporting binding energies for muonic atoms as done for electrons in the case of NIST [1]? Obviously I don't expect such a level of detail, but would be useful if something ...
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Why does greater the distance between light source and screen in the diffraction results in smaller error of wavelength?

So I just did an experiment about diffraction grating to understand the spectrum of atoms and I got a weird correlation that greater the distance between light source and screen caused a smaller error ...
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Is my understanding of the limitations of the Bohr model related to atomic spectra correct?

I'm talking about a neutral hydrogen atom here: According to Bohr, if the electron jumps from $n=2$ to $n=1$, there'd be only one wavelength of light being emitted. However, that is not the case we ...
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What is the magnetic quantum number for $p_x$, $p_y$, $p_z$?

After tons of research, I've come to the conclusion that the $p_x$ and $p_y$ orbitals can have either $m_\ell=+1$ or $-1$, but $p_z$ is $0$. But my professor said that we can attribute any $m_\ell$ ...
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22 votes
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As there is no specific boundary of an atom, how was Rutherford able to estimate the size of an atom?

On the basis of the observations, Rutherford drew the following conclusions regarding the structure of an atom: Most of the space in the atom is empty as most of the alpha particles passed through ...
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How many gold atoms can fit around earth's equator?

I know that earth has a radius $R_E = 6371\,km$ and gold has the following properties: $\rho_{Au} = 1.932 \cdot 10^4 \frac{kg}{m^3}$ $M_{Au} = 196.9666 \cdot u \quad (u = 1.66054*10^{-27}\,kg)$ ...
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Invalid structure of atoms on a classical scale and wrong assumption for the time of publication

(Actual question at the very bottom) In his 1911 paper "The scattering of α and β particles by matter and the structure of the atom" Rutherford starts with this assumption: Consider an atom ...
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Units in Bohr's model of an atom

In the Bohr model the values of the orbital kinetic moment and of the allowed radii are quantized according to : $$mv_nr_n = n \hbar, \, r_n = \frac{n^2 \hbar^2}{me^2}$$ By combining the two, i get : $...
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Number of electrons in an atom referenced by Rutherford

I have been reading the original paper of Rutherford and came across his reference of a paper from J.A. Crowther. Crowther concluded that the number of corpuscles in an atom is equal to about three ...
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What's the difference between $ΔE_{\rm atom} = (Δn)hv$ and $ΔE_{\rm atom} = hv$?

I'm so much confused with so look-alike formulas ; So to begin with: How is this Different to this They are basically the same ΔEatom And last question: In this picture, we can use ΔEatom for any ...
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Is atom mostly empty space or not? [duplicate]

I have read in many science popularizing articles that atoms are mostly empty space but on more research I have found that that is not the case since what interacts generally with the surrounding is ...
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Air and Empty Space

Dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases Which means if I were to take a differential volume dV of air, at any instant of ...
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Why excited electrons come back to ground or some intermediate level?

Everything I have read did not explain it at all and just stated the fact. So WHY (what specific forces involved) excited electron spontaneously comes back to ground energy levels. Is it nucleus ...
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Number of neutrons per same weight samples

I've stumbled on this question that I can't seem to figure the answer of: Which of the following 4 samples contains the least number of neutrons, considering that they all have the same mass. ...
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What exactly happens in a slit and behind it?

In the considerations in many QM books the usual simple scheme of a slit is represented and a plane wave (e.g. particles of almost fixed velocity) are falling on it. After the slit one has (if the ...
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Corrections to energy levels in many-electron atoms

While I've been solving the Hydrogen atom problem, using quantum mechanics, I came across several correction factors, that give rise to the fine structure of the hydrogen spectrum. The Hamiltonian can ...
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What is the fastest velocity that has been observed for an atom?

I know that particle accelerators have sent electrons to velocities that are significant percentages of the speed of light. My question is instead, have they done the same with atoms? And do the ...
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Internal structure of atomic nuclei

When one considers the decay chain of heavy elements, alpha decay forms a significant part of the decay series. This make me wonder about the internal structure of atomic nuclei. When atomic nuclei ...
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What is the atomic explanation for why some materials cannot be magnetized? [duplicate]

I have heard many variations on the explanation for why certain materials like iron can be magnetized by being stroked with a magnet, but I haven't yet found any source directly explaining why some ...
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When two molecules collide, does it produce a sound?

When we are in an empty room with no one around, we don't hear any sound, but there are billions of atoms and molecules that are colliding at the same instant. So my question is, when two molecules ...
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Would the electric force on electrons be larger if the neutrons were polarized by protons inside the core instead they weren't polarized?

Would the electric force of the nucleus on electrons be larger if the neutrons were polarized by protons, compared to if they weren't polarized? Would neutron polarization add some extra force acting ...
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Where does the kinetic energy of recoil in hydrogen come from?

I came across a rather simple question asking the recoil speed of hydrogen atom when it releases photon while electron goes from n=2 to n=1. The photon emitted will have energy released during the ...
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State of atom build from ion?

If an atom builds up from an ion capturing an electron which state of the atom is more probable as a first transition (immediate after capturing) - with higher energy (excited state) or lower (more ...
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Can we simulate hydrogen atom formation?

Is it possible to simulate the formation of a hydrogen atom from a single free electron and a free proton? The Hamiltonian for the Schrodinger equation of a free electron and free proton is the same ...
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