History of the Periodic Table of the Elements (CHEM 1360) Part 1

1. History of the Periodic Table of the Elements (CHEM 1360) Part 1

2. Democritus 460?-370? B.C. Proposed matter was composed of indivisible particles he called “atoms”

3. Lucretius — 95?-55? B.C. Roman poet and philospher who attempted to explain sensory appearances of matter on physical properties of atoms

4. “Honey and milk are pleasant to the tongue. . . . From smooth round atoms come those things which touch Our senses pleasantly. . . .”

5. “But wormwood and red gentian both are bitter. . . .”

6. “Little spurs projecting just a bit, to tease our senses, To tickle rather than sting, like wine or elecamphane. . . .”

7. “Hard things. . . flint, iron, bronze. . . tight knit, Must have more barbs and hooks to hold them, Must be more interwoven, like thorny branches. . . .”

8. “Water must be composed of rounded particles. . . . and salt atoms are roughened and pitted. . . .”

9. According to Lucretius, the properties of matter observed by us depend on the physical behavior and motion of atoms (while the atoms themselves do not possess these properties). FOR EXAMPLE: • Lemons are sour not because lemon atoms are sour, but because lemon atoms are ragged and scrape across the tongue. • The saltiness of ocean water is not due to salt atoms that taste salty, but because salt atoms have pitted and rough surfaces that rub on the tongue. In fact, the rough salt atoms can be removed by filtering through earth — the rougher surface helps them stick in earth.

10. Aristotle (384-322 B.C.) believed in a primordial substance that is the basis of all matter in the universe.

11. Change the qualities of wetness, dryness, hotness, coldness Earth Fire Primordial Matter Air The four “elements” of Aristotle result Water According to Aristotle, one form of matter can be transmuted into another by simply changing the qualities of the primordial matter.

12. Tin Bronze Copper As an example of Aristotle’s philosophy, we can blend the quality of “tin” with the quality of “copper” to obtain a new quality of “bronze.”

13. Aristotle’s idea of primordial matter which could be subtly varied by Nature was reinforced by observations by miners. Silver, for example, can be observed to grow into intricate forms — proof, it was thought, that metals are alive.

14. Just as caterpillars can transmute into butterflies, we see all of Nature is constantly striving for perfection. Thus, all metals in the bowels of the earth are evolving. . . .

15. And we see the even basest of metals — lead — slowly transforming in nature into the most perfect metals of all — gold.

16. The contribution of Democritus and Lucretius was the concept that matter is composed of tiny particles which may look very strange indeed and whose behavior on an atomic scale determined how the matter was perceived and sensed by us. The contribution of Aristotle was the idea of primordial matter. This concept laid the foundation for the dreams of alchemists who aspired to duplicate Nature and transmute base metals into gold, thereby discovering thousands of new chemicals. After the true “immutable” elements were discovered (Lavoisier, 1789), Aristotle’s idea led, in the twentieth century, to the discovery of the “primordial matter” of protons, electrons, and neutrons and to the realization that elements were not really immutable after all.