From Alchemy to Physics: Converting Lead into Gold

Gold-without doubt the most spell-bindingly beautiful of the metals to behold! In addition to its metallic yellow magnificence, gold is limited in abundance, and in very heavy demand for many applications based on its marvelous properties. For these reasons, it has been the dream of many persons to discover gold and to gain a fortune in so doing. The pursuit of yellow gold is not merely a modern phenomenon. It has been the driving force of treasure-seeking, grand larceny, and-at times-even murder. The lust for gold serves well as the symbol of greed.

Turning to Pseudo-Science

Alchemy is a kind of hybrid blend of philosophy with science. The goals of the alchemist were to find the impossible to achieve. The tool to be used was a substance labeled the "philosopher's stone." It may have had its roots in pagan religion. Among its range of capabilities would be converting something as ordinary as lead into the precious yellow gold. The search, as we know, was in vain. There is no true scientific basis for such a tool. Yet, during the 20th century, physicists would find a tool comparable to the philosopher's stone, that actually would and did enable them to convert the soft, gray, lead into gold.

Physicists' Success

Physicists can convert lead into gold by causing a net change in protons contained in the atomic nucleus¹ (also called the atomic number) (lead, atomic number 82, yields gold, atomic number 82, plus 3 protons). How is this done? One suggested method² is by bombarding lead-204 atoms with hydrogen-1 nuclei to form the intermediate bismuth-205 atoms, which would then eliminate two alpha particles (helium-2 atoms) to form Gold-197. Notice how the atomic numbers and the atomic weights of each element all balance.

Atomic number: Lead 82 + Hydrogen 1 → Bismuth 83 → Gold 79 + Helium 2 x 2.

Atomic weight: Lead 204 + Hydrogen 1 → Bismuth 205 → Gold 197 + Helium 4 x 2.

Why is Gold Still Rare?

With such a process combining inexpensive hydrogen gas and lead, why isn't gold manufactured in this way, making it both abundant and cheap? For very good reason. The energy required to bombard the lead atoms into bismuth, which would decay into gold, costs much more than the gold would be worth.

¹ The number of protons in an atom's nucleus is called its atomic number.

²Rutgers University Physics and Astronomy Education Research Group

Resources:

LeMoyne College - Selected Classic Papers - History of Chemistry

University of Nevada, Las Vegas - Transmutation Research Program Annual Report 2001