113
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How can we see an atom now? What was the scale of this equipment?
The questions of whether you can detect light emitted from an (isolated) atom and whether you can resolve an atom from its neighbours are completely independent.
The spacing between different atoms ...
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83
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If an apple is magnified to the size of the earth, then the atoms in the apple are approximately the size of the original apple
In "back of the envelope" calculations like this, all you can really do is look at orders of magnitude. As others have pointed out, not all apples have the same size, and not all atoms have ...
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41
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How did Rutherford conclude that most of the mass (as well as the positive charge) was concentrated in the nucleus?
This is a good example of how Science works.
Geiger and Marsden observed that some of the alpha particles were being backscattered. This is inconceivable if the alpha particle is scattered by a ...
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How did Rutherford conclude that most of the mass (as well as the positive charge) was concentrated in the nucleus?
Wikipedia explains this rather well but I'll pick out the relevant stuff for you.
Before the Geiger–Marsden experiment, the general idea was that atoms were built of some permeable positive substrate ...
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Why are line spectra only seen in gases?
In liquids and solids the difference in energy between energy levels becomes very small, due to the electron clouds of several atoms bein in very close proximity of one another. These similar energy ...
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36
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How can we see an atom now? What was the scale of this equipment?
To be fair, this is actually explained in your link. To put it simply,
If you illuminate it with the right light, it starts shining so bright that a good camera can detect it.
To make it work, the ...
36
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When two molecules collide, does it produce a sound?
A sound wave is a synchronised movement of millions and millions of atoms or molecules. The random collisions of atoms or molecules are not synchronised and do not produce a sound wave.
A sound wave ...
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33
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How does Brownian motion prove the existence of atoms?
Einstein's mathematical model of brownian motion furnished strong support of the atomic model but did not furnish airtight proof of its uniqueness (that is, the nonexistence of alternative models) at ...
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31
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To what degree of precision are atoms electrically neutral?
See
Bressi, G., et al. "Testing the neutrality of matter by acoustic means in a spherical resonator," Physical Review A 83, (2011): 052101 (DOI: http://dx.doi.org/10.1103/PhysRevA.83.052101)...
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30
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As there is no specific boundary of an atom, how was Rutherford able to estimate the size of an atom?
Rutherford probably estimated the size of gold atoms
as already sketched by @AndrewSteane in his comment.
The density of gold is $\rho=19.3\text{ g/cm}^3$.
The molar mass of gold was known from ...
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28
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Is Avogadro's law applicable for atoms or just for molecules?
I notice that online definitions of this experimental law always say, molecules or atoms.
The problem with just calling them all "molecules" and being done with it is some are uncomfortable with ...
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28
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Are all atoms spherically symmetric? If so, why are atoms with half-filled/filled sub-shells often quoted as 'especially' spherically symmetric?
In general, atoms need not be spherically symmetric.
The source you've given is flat-out wrong. The wavefunction it mentions, $\varphi=\frac{1}{\sqrt3}[2p_x+2p_y+2p_z]$, is in no way spherically ...
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26
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What exactly is the shape of an atom as per modern physics?
The confusion arises because you have not yet learned much about quantum physics. Quantum physics is the most accurate and wide-ranging set of concepts and mathematical methods in physics, and it ...
- 60.2k
24
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If an apple is magnified to the size of the earth, then the atoms in the apple are approximately the size of the original apple
Your question starts out with questioning whether the numbers match up very well, and then you proceed to throw away all the accuracy in your numbers to demonstrate that they don't.
While throwing ...
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23
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To what degree of precision are atoms electrically neutral?
The best bounds I am aware of come from cosmology. (Unfortunately, I know from experience that this is not something that the Particle Data Group tracks very assiduously.) If there were charge ...
Buzz♦
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21
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Why are line spectra only seen in gases?
You see line spectra usually only in gases because there the interaction between the atoms can be neglected. In gases with high pressures you get the so-called collision broadening of the lines which ...
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21
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Why don't electrons fall or collapse around atom when an object accelerates rapidly?
At first, as others have said,- you transfer car momentum to a whole atom system, not just to some part of it,- like electrons, nucleus, etc.
Second,- an electron is not something you can easily mess ...
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20
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Why don't electrons fall or collapse around atom when an object accelerates rapidly?
The laws of motion you are quoting are the classical Newtonian mechanics laws. They do not hold as such at the quantum level, they are emergent for energies and distances where classical mechanics ...
- 235k
20
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How does removing air from a vessel of water create bubbles?
Basically, oxygen and nitrogen, like carbon dioxide, are soluble in water. The higher the pressure in the water, the more soluble they are.
Remove the pressure and they come out of solution, in the ...
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20
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How can we experimentally confirm that atoms/molecules in a solid actually "move"?
The motion of atoms can be studied using various techniques based on neutron scattering. Unlike X-ray scattering, where X-rays are reflected by the electronic clouds surrounding atoms, neutrons are ...
- 61.9k
20
votes
Is Pauli's Exclusion Principle a restatement of what experiments have shown?
I'll take a swing at this, from the standpoint of a puzzled high schooler, which I myself was 52 years ago.
Experiments showed that there were orbitals surrounding nuclei which contained not one but ...
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19
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How can an electron shell hold more than two electrons?
A "shell" is the term for all states with the same principal quantum number $n$, but in each shell there are also possible different values for the angular momentum quantum number $0\leq \ell \leq n$, ...
- 127k
19
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As there is no specific boundary of an atom, how was Rutherford able to estimate the size of an atom?
The size of the atom was estimated before Rutherford did his alpha particle experiment.
One way is to take a drop of oil of known radius and put in on water. It spreads out, given some time, to a ...
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18
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How can we see an atom now? What was the scale of this equipment?
While the physics has already been covered in other answers, let me give you an idea about how to explain the difference between detection and resolution to a 4-year old:
Try an analogy. Something ...
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17
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Does an atom recoil when photon radiate?
The momentum of a photon is not only defined, but is defined very well in the famous Einstein's quation:
$$ E = \sqrt {(mc^2)^2 + (pc)^2 } $$
that leads for massless photons to
$$p=\frac Ec =\...
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17
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How come the number of wandering electrons is same as the number of the positive ions?
The paragraph should be read as "The total charge of the wandering electrons equals the total charge of positive ions". The actual number of positive atoms may be less, but that is offset ...
- 41.9k
17
votes
What exactly is the shape of an atom as per modern physics?
The electrons in an atom do, in a sense, orbit its nucleus. However, if you imagine this as being like planets orbiting a star then this picture is misleading.
One difference is that the shapes of the ...
- 57.6k
16
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In an atom, when an electron loses energy, why is a photon released? If photons are massless, how are they created in this process and why?
We believe that there exist something called an electromagnetic field, this is an invisible interaction, just like gravity that pulls you down, the electromagnetic field is a force that acts on ...
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Accepted
Is it true that the interior of an atom is mostly vacuum or empty space?
I will answer the question by comparing empty space and
vacuum with the properties of the interior of an atom.
I will write at the level of high school physics in order to make my answer accessible.
...
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15
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Accepted
How can we see objects with the help of light if we cannot see atoms?
As explained in a related previous thread, the human eye cannot resolve atoms (in the sense that visible light is too coarse to distinguish one atom from its neighbours in solids and liquids), but ...
- 135k
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