Talk:History of atomic theory

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Archives: Index 1

This page has archives. Sections older than 90 days may be automatically archived by when more than 4 sections are present.

Relativistic atom

Would a comment on Walter Gordon (physicist) on solving the relativistic equation (Dirac equation) for the hydrogen atom be of interest here? What about the Lamb shift? Or are these ideas heavily focused on hydrogen? ReyHahn (talk) 12:20, 23 March 2024 (UTC)[reply]

Hydrogen is simply the iconic atom. Both issues are related to atomic theory IMO. Johnjbarton (talk) 17:43, 23 March 2024 (UTC)[reply]

Energetics

Maybe a mention to Ostwald's energetics could fit in the statistical mechanics section. ReyHahn (talk) 09:36, 19 April 2024 (UTC)[reply]

Mass of an electron

@Johnjbarton: The article says that Thomson measured the mass of an electron to be 1/8000 of a proton. But I looked through Thomson's paper and he didn't measure the mass, but the mass-to-charge ratio. When was the mass measured? Was it Milikan's oil drop experiment? If you measure the charge of an electron and you already know the mass-to-charge ratio, you can then calculate the mass. Kurzon (talk) 12:00, 14 May 2024 (UTC)[reply]

I didn't find 8000, but I did edit the m/e section for the electron based on Whittaker. Johnjbarton (talk) 18:17, 14 May 2024 (UTC)[reply]

@Johnjbarton: In his 1899 paper, Thomson writes: "This mass is exceedingly small, being only about 1.4 × 10^-3 of that of the hydrogen ion". Does that mean the electron is 1,400 time smaller than hydrogen, or 1/0.0014 times smaller? Kurzon (talk) 18:35, 14 May 2024 (UTC)[reply]

"being only about" 1.4 times 1/1000 times hydrogen ion. So 700 times less massive, my mistake. (and it's not smaller but lighter) Johnjbarton (talk) 18:43, 14 May 2024 (UTC)[reply]

@Johnjbarton and Ajrocke: How did Thomson know the charge on a hydrogen ion is equal to the charge on an electron? Which papers did he lay out his proof? Kurzon (talk) 09:21, 15 May 2024 (UTC)[reply]

Doesn't this follow from charge neutrality? The hydrogen atom is neutral.--ReyHahn (talk) 09:29, 15 May 2024 (UTC)[reply]

Thomson measured e for ions and for photo-electrons. He measured m/e for cathode rays and photo-electrons. In his photoelectron paper he says

W. Wien (Wied. Ann. lxv. p.440) and Ewers (Wied. Ann. lxix. p.187) have measured the ratio of m / e for the positive ions in such a tube, and found that it is of the same order as the value of m / e in ordinary electrolysis; Ewers has shown that it depends on the metal of which the cathode is made. Thus the carriers of positive electricity at low pressures seem to be ordinary molecules, while the carriers of negative electricity are very much smaller.

Johnjbarton (talk) 22:04, 15 May 2024 (UTC)[reply]

Well I don't think at the time Thomson knew that a hydrogen atom had just one electron. Kurzon (talk) 09:59, 15 May 2024 (UTC)[reply]

Multiplier/multiples

@Johnjbarton: Let's revisit this issue.

In an April 1911 paper, Ernest Rutherford estimated that the charge of an atomic nucleus, expressed as a multiplier of hydrogen's nuclear charge (e), is roughly half the atom's atomic weight, based on how various types of metal foil scattered alpha particles.

I think it should be "multiplier".Kurzon (talk) 18:30, 18 May 2024 (UTC)[reply]

? I guess this is a quote from somewhere. But it is unrelated to the discussion on Rutherford scattering experiments. In the quote above "multiplier" seems fine to me. The other sentence was different and anyway I removed it for other reasons. Johnjbarton (talk) 19:06, 18 May 2024 (UTC)[reply]