“Writer, physician, and
Doctor Graham Travers:
Last role, pseudonymic, for
Margaret G. Todd.
Term ‘isotopic,’ her
Etymologic endeavor,
Will clarify masses at odds.”
The 14 April 2022 Twitter biography poem alluded to some of the many STEM-related achievements of physician Margaret Todd (1859-1918), including a contribution to the disciplinary vocabulary of chemistry.
“Writer, physician, and /
Doctor Graham Travers: /
Last role, pseudonymic, for /
Margaret G. Todd…”
Margaret Georgina Todd was a Scottish writer and doctor. The first two lines seem somewhat redundant in describing her career (“physician and doctor”), but as the third and fourth lines note, “Graham Travers” was the pseudonym under which she wrote her most famous book: Mona Maclean, Medical Student.
“Term ‘isotopic,’ her
Etymologic endeavor,
Will clarify masses at odds.”
In the field of chemistry, Todd is known for proposing the term “isotope,” in a conversation with radiochemist Frederick Soddy.
Soddy had been studying elemental forms that corresponded to the same entry on the Periodic Table of the Elements (PTE). These species shared the same atomic number (number of protons) but were seen to behave chemically differently in some scenarios, which could be ultimately attributed due to their different mass numbers (number of protons plus number of neutrons). Via collaborations with Ernest Rutherford, Soddy developed the concepts of nuclear reactions and radioactivity, proposing processes by which some of these intriguingly different chemical entities could decay into one another.
Learning about this research, Todd suggested a new term (“etymologic endeavor”) with which to describe these interesting species. She proposed the word “isotope,” from the Greek for same (“iso”) and place (“topos”), since isotopes are located at the “same place” on the PTE: they are instances of the same element.
At the macroscopic level, the behavior of isotopes explains why atomic weights (average atomic masses, represented by the numbers underneath the chemical symbols on the PTE) are not whole numbers: different isotopes are present on Earth in different “abundances,” ultimately resulting in fractional values for these average quantities.
Chemphasis 