John Jacob Livingood made radium E (210Bi) by bombarding common bismuth with deuterons, 1936, the first synthetis of a radioactive substance in the US.
Pierre-Louis Dulong born 1785: discovered nitrogen trichloride; refractive indices and specific heats of gases; law of Dulong and Petit (specific heat times atomic weight is the same for many elements); suggested that acids were compounds of hydrogen; formula for heat content of fuel (Dulong formula)
Synthesis of diamond by Francis Bundy, H. Tracy Hall, Herbert Strong, & Robert H. Wentoff, Jr., at General Electric Research Laboratories announced in 1955.
Julius Thomsen born 1826: heats of reaction, relative strength of acids, manufacture of soda from cryolite
Helen Murray Free born 1923: diagnostic chemistry: reagents and instrumentation for clinical diagnosis in blood and urine chemistry, histology, and cytology
Pierre Jules Cesar Janssen born 1824: astronomical spectroscopy and photography, particularly of the Sun; found a line in the solar spectrum subsequently identified with helium.