- Helium, neon, argon, krypton, xenon, and radon never form compounds. We called them "inert gases". But compounds of xenon were synthesized in 1962. The discoveries have continued, most recently the synthesis of a helium compound in 2013. Neon is the only holdout — for now.
- Cosmic rays are electromagnetic. The textbooks said cosmic rays are similar to radio waves, infrared, visible light, ultraviolet, and X-rays, all of which are photonic and comprise the electromagnetic spectrum. This understanding of cosmic rays never had much experimental evidence and was rejected in the 1950s. Cosmic rays are, in fact, high energy particles; 90% are naked protons.
- Most positive integers have an odd number of prime factors. This assertion of mathematics appeared in 1919, and it's true for numbers that you can test with pencil and paper. But in 1958 a mathematician proved that a counter-example existed, and two years later a computer that could do arithmetic with very large numbers found it.
- Protons and neutrons are indivisible particles. This assertion was completely smashed (pardon the pun) by the theory of quarks, first published in 1964.
- Radioactive atoms decay into atoms of elements of fewer protons, like uranium to lead. Half the story. Radioactive atoms also decay into atoms of more protons through a process called beta minus decay. The classic example is the transmutation of carbon-14 (atomic number 6) to nitrogen-14 (atomic number 7). Although beta minus decay was proposed as far back as 1913, understanding its mechanism required knowledge of quarks. See above.
Saturday, August 8, 2015
Errors in what we were taught
In January I blogged that the traditional depiction of a lithium atom is spectacularly wrong. Here are other items in physics, chemistry, and mathematics taught to my generation in the late 1960s and early 1970s that were dubious or downright wrong even while we were in the classroom:
at 7:28 PM