Some history of nuclear models

Some history of nuclear models

An excellent semitechnical review of nucleosynthesis in the universe is by Jennifer A. Interested readers may wish to know that it was published by Johnson. Science on February 1, 2019 (DOI: 10.1126/science.aau9540). It is called „Filling in the Periodic Table: Nucleosynthesis of the Elements” And Figure 1 has a periodic table showing how the elements are formed in the universe. The timetable in the C&EN article is almost identical.

As part of the history, on page 32, Borzak says, “In the 20th century, physicists and chemists settled on a basic picture of the atom. At the dawn of the 1900s, the electron was discovered. Since scientists knew that atoms were electrically neutral, they pictured atoms as packed together with electrons and positively charged particles all mixed together. „Ernest Rutherford and his collaborators proved this wrong,” Borczak says. I once asked Peter Debbie if he took the plum-pudding model seriously. He didn't, they didn't really know what was going on.

Why was the plum-pudding model proposed? In classical electrodynamics, an accelerated charged particle was known to emit radiation, as given by the Larmor formula. As an electron orbiting a nucleus accelerates, it must radiate and spin the nucleus. After Rutherford invented the planetary model of the atom, Niels Bohr explained this violation of Larmor's formula by stating that the electron can only exist in certain energy levels and jump between these levels, at which point radiation is emitted. There is a lower energy state called the ground state. The spectral lines of hydrogen show this very well.

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Thanks again for this and all the great articles you post.

Harvey F. Carol

Lake Forest Park, Washington

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