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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Did Democritus predict atoms using sharp phase transitions

In the Wikipedia page for the Ising Model it is written without citations: One of Democritus' arguments in support of atomism was that atoms naturally explain the sharp phase boundaries observed in ...
Diana's user avatar
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In Geiger-Marsden experiments how was charge of alpha particle and charge of gold atom found?

Here: https://en.wikipedia.org/wiki/Geiger%E2%80%93Marsden_experiments Some calculations were done to show how JJ Thomson's model predicts alpha particles will be mostly undeflected by the gold foil. ...
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A summary of Major events in Pre-Modern Atomist Philosophy of Chemistry [closed]

When I started learning about Laws related to "constant proportions" and other hypothesis like "all matter is composed of smallest indivisible particles", I didn't notice it was ...
Dheeraj Gujrathi's user avatar
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2 answers
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Did the plum pudding model of the atom make any successful predictions?

Bohr’s model of the atom predicted hydrogen’s spectral emissions lines —— a huge success. What about Thomson’s plum pudding model? Did it make any successful predictions?
littleO's user avatar
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The case of Felix Exner and Brownian motion

I'm reading some articles about the history of Brownian Motion, for example, that of Maiocchi (https://www.jstor.org/stable/4026755) or Genthon (https://arxiv.org/pdf/2006.05399.pdf), and they all ...
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On Einstein's argument at the beginning of his PhD thesis

In Investigations on the theory of Brownian movement, he says that osmosis holds for solute particles but not for Brownian ones, since they are too big to pass through a permeable membrane. So what? ...
ric.san's user avatar
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Who popularized the atom icon (atomic whirl or planetary model)

There is a symbol or icon for an atom that is instantly recognizable and is associated with nuclear physics and with chemistry. A search for "nuclear atom symbol" (on 3/23/2023) shows what ...
Karsten Theis's user avatar
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When was the hydrogen's absolute mass found first in history?

When was hydrogen's absolute mass i.e, in Kg, was found for the first time. What method was used and what information from earlier researches were used for it? Also was there any method at that time ...
Arsenal Creation's user avatar
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How did Thomson claim that charge on hydrogen ion was equal to charge on electron without knowing charge on electron?

From "The Electron" by J. J. Thomson, published in The Scientific Monthly Vol. 20, No. 2 (Feb., 1925), pp. 113-115 https://www.jstor.org/stable/7115 [Continued discussion] previously ...
Arsenal Creation's user avatar
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Why were Cathode ray tubes first invented?

Cathode ray tubes have played a very important role in the development of physics around 1900. They have also served as a key component in old-fashioned TVs. This is great and all, but what was the ...
Maximal Ideal's user avatar
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How did they explain the radiation from hot objects at different wavelengths before the concept of atom was widely accepted?

I was reading about blackbody radiation and came across the following quote. Planck did not believe in atoms, nor did he think the second law of thermodynamics should be statistical because ...
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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. ...
Adil Mohammed's user avatar
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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"....
AChem's user avatar
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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 ...
Solidification's user avatar
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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, ...
Deschele Schilder's user avatar
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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 ...
Hayden Soares's user avatar
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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 ...
Mark Morales II's user avatar
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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 ...
user3518839's user avatar
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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. ...
Nachiket Kulkarni's user avatar
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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 ...
Eric David Kramer's user avatar
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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 (...
AChem's user avatar
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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: ...
Hans-Peter Stricker's user avatar
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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 ...
Sedumjoy's user avatar
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5 votes
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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 ...
Sedumjoy's user avatar
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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 ...
StopReadingThisUsername's user avatar
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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. ...
Elle Najt's user avatar
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1 answer
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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 ...
Sedumjoy's user avatar
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1 vote
1 answer
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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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2 answers
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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 ...
futurePast's user avatar
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1 answer
146 views

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 ...
Shivay Vadhera's user avatar
4 votes
1 answer
288 views

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.
Dude Threefourseven's user avatar
16 votes
1 answer
954 views

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 ...
Mikhail Katz's user avatar
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4 votes
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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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1 answer
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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 ...
user avatar
10 votes
2 answers
2k views

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?
FNH's user avatar
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9 votes
1 answer
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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 ...
StopReadingThisUsername's user avatar
13 votes
2 answers
1k views

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 ...
TripeHound's user avatar
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1 answer
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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 ...
VicAche's user avatar
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4 votes
1 answer
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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?
Quantum spaghettification's user avatar
11 votes
1 answer
647 views

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 ...
Ellie Kesselman's user avatar
8 votes
2 answers
237 views

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 ...
mau's user avatar
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29 votes
1 answer
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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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