Dmitri Mendeleev (1834 – 1907) Дмитрий Менделеев, “Principles of Chemistry”, 1868 was the topic of an earlier blog post.
Here I present: Frederick Soddy, (1877-1956) “The Origins of the Concept of Isotopes”, NOBEL PRIZE LECTURE, 12 November 1922.
Summary.
The Scottish doctor/writer Margaret Todd (1859-1918) coined the term “isotope” in a suggestion to Frederick Soddy (1877-1956) the Scottish English radiochemist in 1913.
Reference.
Frederick Soddy, “The Radioelements and the Periodic Law”, Chemical News, volume 107, year 1913, pages 97-99. was the source for the suggestion of the term “isotope” from Margaret Todd in 1913.
Etymology.
Isotope is a noun in the 1913 sense of the Margaret Todd definition. The term is composed of the Greek language “isos” (equal). The term is also composed of the Greek language “topos” (place). Hence, in the English language the term isotope, is to mean literally “having the same place”. Isotope is a variety of forms of the element occupying the same periodic table place.
Here I presented Frederick Soddy, (1877-1956) “The Origins of the Concept of Isotopes”, NOBEL PRIZE LECTURE, 12 November 1922.
COMMENTS.
Margaret Todd of the Edinburgh, SCOTLAND School of Medicines for Women was the first one connect to levels of anatomy, shown BELOW by coining the term “isotope” for Frederick Soddy.
These levels of the “chemical” that the ancient and medieval alchemist had no words for.
0. Electronic Photon.
1. Elemental Electron.
2. Electronic Element.
3. Isotopic Element.
4. Elemental Molecule.
5. Cellular Molecule.
6. Molecular Metabolism’.
Frederick Soddy was modern radiochemist, and the term “isotope” distinguished him from ancient alchemists, who used the term “elements”. Aristotle the founder of the Lyceum of Athens GREECE was the source the term “element” in text titled ”PHYSICS”; and, Frederick Soddy redefined “element” with the “isotope” concept for the modern world.
The “Soddy Law” is shown in the diagram BELOW. The law describes “radionuclide displacement” in a graphic. Horizontal axis: protons number Z. Vertical axis: neutrons number N.
The law describes which chemical element and isotope is created during the particular type of radioactive decay: alpha decay (α), beta decay (β-), electron capture (EC, β+), neutron capture (n), proton capture (p).
A type of Frederick Soddy periodic table of elements is shown BELOW. The vertical axis (Z) is atomic number: 1 H (hydrogen), 2 He (helium), 3 Li (lithium), 4 (beryllium), 5 B (boron), 6 C (carbon) … etcetera… at bottom left.
The entire isotopic elements Periodic Table is shown BELOW. 
The color of the chart are described as BELOW. “Black” color is for “natural abundance”; and, the 25 essential elements are those of “natural abundance”.
