The Jock Strap of Atomic Theory

Chances are, you’re not like me: you cringe when someone says the word “chemistry.” Your memory of it vaguely harkens back to an undergrad class whose knowledge you flushed once you finished the final. That’s okay — my goal for this series is to change that paradigm, make it understandable to all, and provide some entertainment.

There are two very important things to remember about John Dalton and the beginning of atomic theory:

1) Dalton had no direct physical evidence of atoms.

Zip. Zilch. Nada. Due to this hard to ignore fact, his theory was relegated to chemistry “meta” in some circles of researchers. He did have an abundance of indirect evidence, though, and his theory fit well with the previously established framework.

2) Dalton’s atomic weight system was relative and arbitrary.

Dalton himself recognized these two pieces of the theory could be troublesome. His weights were based off of the fact that since hydrogen was the lightest gas, it should be the benchmark and that all other weights would be based off setting hydrogen’s atomic weight to one.

While he published, presented, and argued his theory until he was blue in the face, he needed to win over minds — he needed support. To accomplish this, other chemists need to incorporate the theory into their work and expand its utility. This article is about two gentlemen who basically acted as atomic theory’s jock strap. (See what I did there? “Jock strap” and “support”?)

The first unsuspecting Dalton wingman was Joseph Louis Gay-Lussac (1778–1850, we’re just going to call him “JGL”). As the son of the king’s lawyer, JGL was one of those well-off scientists we’ve read about a few times now. He studied under Berthollet and Fourcroy, both of whom were students of Lavoisier, so JGL was drinking almost directly from the fountain of greatness. Interestingly, after his forced sabbatical, Berthollet returned to a city south of Paris called Arcueil where he basically started the French version of the Royal Society. Many famous chemists ended up spending time in Arcueil, which lead to the development and…