Questions tagged [atomic-theory]

For questions about the history and origin of atomic models and atomic theory. Topics include the classical Greek atomism and the development towards the atom models of Dalton and Rutherford.

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How did Niels Bohr arrive at the second postulate of his atomic model?

Niels Bohr's second postulate of the Atomic Model states that the electron revolves in specific orbits in which the electron's angular momentum is an integral multiple of $\large\frac{h}{2π}$. Since ...
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Bohr's idea of 1, 2, 3 and 4 energy levels in which are 1, 2, 3 and 4 pairs of electrons

In his book VALENCE and The Structure of Atoms and Molecules Gilbert Newton Lewis wrote We may next consider a very recent idea advanced by Bohr (1921), which is not based so much upon deductions ...
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How did Rutherford detect the deflected alpha particles?

All I know is that detecting the deflecting alpha particles was a very tedious process, so much so that that was probably one reason why he asked Hans Geiger and Ernest Marsden to do the experiment. ...
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Earliest measurement of proton's mass

I was looking for the earliest experiment or the paper which shows the determination of the mass of proton. In NIST CODATA, the mass of proton is listed as "1.672 621 923 69 x 10$^{-27 }$kg"....
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Around 1904, did the scientific community take the atomic hypothesis seriously?

The time when Thomson discovered electrons, around 1897, what did the scientific community think about the atomic hypothesis? Was there a majoritarian consensus that matter is made of indivisible ...
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What was the attitude towards atoms around the turn of the nineteenth century?

Einstein invented, on his own, a statistical mechanics, presupposing the existence of atoms. I can't imagine he was unaware of the shortly-before-invented statistical approach by Boltzmann and others, ...
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How did Antonius Van den Broek come up with his hypothesis that the atomic number matches the charge of the nucleus?

Antonius van den Broek was the first person to suggest that the atomic number (which at that time only referred to an element's position in the periodic table and had no physical interpretation) of an ...
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What exactly was the Rutherford model of the atom?

I was recently doing research on the "Rutherford model" of the atom. I found that there seem to be three different accounts of Ernest Rutherford's theory circulating online: Electrons move ...
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How did J.J. Thomson learn that what he discovered was different than an atom or a molecule?

Wikipedia says he discovered that the electron was different than an atom or molecule. His line of reasoning is not shown. I additionally searched stack exchange and unless I missed it..... I am lost ...
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Is string theory today facing the same backlash that atomic theory faced during its inception?

I read in this Quanta article that although many critics say that it is far removed from nature, it has developed many powerful tools. Furthermore some don’t care if it’s a theory of everything and ...
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How did Millikan consider utilizing oil to help determine the charge of the electron?

Robert Millikan's oil drop experiment help to find the charge of electrons using oil. An x-ray was aimed at the oil drops to give them a charge, and the droplets were attracted to the negative plate. ...
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On atomism and philosophy of science

The background of this question is as follows. Sean Carroll is in the process of giving a series of talks recorded in his home office and published on YouTube. The setup is intentionally very informal....
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How did Einstein know the Avogadro Number?

Wikipedia says the Avogadro number was determined by Perrin in 1908. But Einstein used the value $$N=6\times 10^{23}$$ as early as 1905 in order to estimate the size of the fluctuations of an ...
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How did early physicists experimentally assign electronic transitions in atoms?

The spectrum of hydrogen was very well studied by the mid-19th century. However, if one were doing experimental spectroscopy for more complex atoms, one would see plenty of spectral lines in the ...
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Who associated the sharp, principal, diffuse, fundamental spectral terms with electron's momentum?

It is well documented that the notation for the electronic configuration (s,p,d,f) of atoms as used today originates from the words sharp, principal, diffuse, fundamental from alkali metal spectra (...
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Did Ludwig Boltzmann read Albert Einstein's publication published on Brownian motion one year before Boltzmann passed away?

Apparently there was some negative reception of Boltzmann's idea of an "atom". I assume the mathematics used by Einstein in his publication did not use any of Boltzmann's statistical mathematics ...
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What was the relation between Euclid's points and Democritus' atoms?

Geometry as described in Euclid's Elements originated roughly at the same same time as Democritus described his atomic theory. I wonder how close these two points of view were related at those times: ...
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Did Sommerfeld derive or measure the fine structure constant the first time he introduced it?

I used Wikipedia to try to figure this out but I am not clear on the explanation. As for Newton's Law of Gravitation does not give the value for the Gravitational constant but it was measured by ...
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What work did Hideki Yukawa do during the Second World War?

Yukawa received a Nobel Prize in 1949 for predicting the pi meson but while in Japan he published his theory which explained the interaction between protons and neutrons in 1935. What work did he do ...
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The Discovery of Atoms

It is not at all obvious that atoms exist and there's no reason why there should be an indivisible unit of matter. Is there an experiment that was conducted which gave strong evidence for the ...
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Before the discovery of the neutron, how did scientists explain standard atomic weights?

The neutron was predicted in 1920 and discovered 12 years later. Before this time, how did scientists explain standard atomic weights? For example, Lithium has a standard atomic weight of about 6.9 ...
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To what extent were the scientists involved in the Manhattan project aware of the goals?

I want to understand the extent to which scientists and technicians employed in the Manhattan project understood that they were building a bomb that would kill hundreds of thousands of people. ...
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Is there any history into the methodology that Balmer used for the spectral line formula?

What I am referring to is the Balmer formula as it appears in Wikipedia. To come up with this series by trial and error along with its constants is asking a little too much but I can't understand how ...
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In what sense did J.J. Thompson split the atom?

I am a little confused on who first split the atom. Wikipedia says that J.J Thomspon did with his cathode ray tube experiments. In what sense does this split the atom? But then it also says ...
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Is this quote from James Gleick about the Manhattan project accurate?

In his book 'Chaos' he says, 'In theory the WWII atomic bomb project was a problem in nuclear physics. In reality the nuclear physics had been mostly solved before the project began, and the business ...
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History of molecular constituency and structure

During times when there was no spectroscopy of any kind, people did make guesses on the molecular constituency and structure. For example, John Dalton's original atomic hypothesis was that all ...
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How was proton determined to be a common component of all atoms?

Based on what I know of the discovery of positive charges, Thompson measured the $e/m$ ratio of various nuclei and their $e/m$ ratio (charge-to-mass ratio) was not constant. People did not know ...
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Who first noticed violation of aufbau principle of elements like Cr, Cu, Pd, Au, and how?

It is often referred to as 'anomalous electron configurations' or 'unusual order of filling of orbitals' of a few elements e.g. Cr, Cu, Nb, Mo, Ru, Rh, Pd, Au etc.
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Hidden agenda of the Galileo trial?

Redondi argued that Galileo's trial on heliocentrism was merely a show trial concealing the real objection against Galileo among the catholic establishment, which was his atomism thought to be at ...
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Atomic models in the 1910's and early 1920's [duplicate]

The Rutherford model that invalidated the plum pudding model occured in 1909, while the first model for quantum mechanics was around 1924, leaving a period of 15 years without an adequate model for ...
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Was there any atomic model(s) that came between Bohr's and the actual beginning of Quantum Mechanics in early 20s?

Well, the question arose in the physics chat when slereah mentioned about it. So, was there any prominent model that came to light after Bohr and before the actual beginning of Quantum Mechanics in ...
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Was Thomson's model of Plum Pudding widely accepted as a model of atom?

Was this model widely accepted in the time as a model for the atom? or was it just a model between many alternatives?
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Dmitri Mendeleev's Periodic Table

Dmitri Mendeleev arranged his first periodic table according to the number of protons and valency electrons. How did he, and others of his age, know of these subatomic particles and electron shell ...
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Did anybody question the indivisibility of the atom because there were "too many" elements?

The realisation that the atom was divisible, and thus that elements were not the "fundamental building blocks" arguably began around 1897 with J. J. Thomson's discovery of the electron and proceeded ...
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Were there alternative names for electron orbitals?

Electrons orbits are referred to as s, p, d, and f, then alphabetically. These stand for sharp, principal, diffuse and fundamental respectively (or maybe the German translations). Was any other ...
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Why did the "old quantum theory" start off considering circular electron orbits?

It seems that both Bohr and Rutherford assumed circular orbits of electrons around the atom. But why did they do so, instead of assuming e.g. elliptical orbits?
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What is the historical reasoning for electron orbital names?

Electron orbitals are referred to as s, p, d and f. I have read that there was a Latinate basis for this, but never found anything more specific. (Obviously, the discovery of electron orbitals by Bohr ...
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8 votes
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When was atomism first considered a scientific theory?

Of course it is difficult, if not impossible, to know whether classical philosophers that talked about atomism thought that "atoms" could be manipulated by men. However, I was startled to know that ...
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What were the dominant non-atomic theories of matter in the 19th century?

From what I have read, the atomic theory of matter was cemented by a 1905 paper by Einstein in which he explained the erratic motion of a bit of pollen suspended in water using the assumption that ...
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