Today In Science History – September 22 – Frederick Soddy and Isotopes

Frederick Soddy
Frederick Soddy (1877-1956) Credit: Nobel Foundation

September 22 marks the passing of Frederick Soddy. Soddy was the English chemist who came up with the idea of isotopes.

With the new discovery of radioactivity, chemists were discovering what they thought were new elements almost constantly. Many of these seemed to be formed from radium, thorium, and uranium. These elements had names like mesothorium, radiothorium, Radium A, B, C, D, E, F and Uranium X, each with a different half-life. Chemists were trying to separate elements like radiothorium from thorium but could find a chemical technique that would accomplish the task.

Soddy theorized many of these new elements were actually all the same elements and could not be separated chemically. They had slightly different atomic masses but were the same elements. He gave the name ‘isotope’ to the atoms in this elemental mixture. He cited radium D and thorium C were actually two different isotopes of lead and behaved the same as lead chemically. Unfortunately, at the time, Soddy couldn’t prove his theory. It would take the discovery of the neutron by James Chadwick to give credit to his theory.

Soddy also described the mechanics of radioactive decay with William Ramsay as the transmutation of one element into another. They showed alpha decay was the emission of a helium nucleus, 2 protons and 2 neutrons which lowered the atomic number by 2 and the atomic mass by 4. Beta decay involved the emission of a beta particle (electron) that raised the atomic number by 1.

Soddy was one of the discoverers of the longer-lived isotope of brevium. Brevium was the original name of the element protactinium. Brevium was discovered by Kasimir Fajans and Oswald Helmuth Göhring by examining uranium decay products. They named their new element brevium after the element’s short half-life of 6.7 hours. Soddy and others found another isotope that had a more stable half-life of 32,000. Since the element wasn’t all that brief anymore, the name was changed to protoactinium because it was part of uranium’s decay chain on the way to actinium. The name was shortened to protactinium in 1949 by the IUPAC.

Soddy would receive the 1921 Nobel Prize in Chemistry for his isotope theory and work on radioactive decay. It was around this time Soddy changed his focus to economics instead of science. He published four books on the subject and led a campaign to restructure the global monetary systems based on the ideas of thermodynamics. For the most part, he was considered a crank for his ideas, but some point to his work as the beginning of ecological economics.

Other Notable Science Events for September 22

2013 – David Hunter Hubel died.

Hubel was a Canadian-American physiologist who shares half the 1981 Nobel Prize in Medicine with Torsten Wiesel for their discovery of the method nerves pass visual information from the eye to brain. Their experiments involved the insertion of a tiny electrode in the visual cortex of a cat’s brain and monitoring the electrical activity as they projected light and dark patterns in front of the cat. They found the brain responded to light patterns different from dark patterns. The other half of the prize went to Roger Sperry for describing how the brain’s hemispheres divide up their functionality.

1979 – Otto Robert Frisch died.

Otto Frisch ID badge
Otto Frisch (1904 – 1979) Los Alamos Manhattan Project ID photo

Frisch was an Austrian physicist who first described the process where uranium atom nuclei split into smaller pieces when bombarded with neutrons and named the process ‘fission’. He took the name from the biological process where cells split into two parts. He was also the first, with Rudolph Peirerls, to discover a possible violent chain reaction of Uranium-235 would take a much smaller mass than the common Uranium-238. This made the atomic bomb a practical possibility.

1956 – Frederick Soddy died.

1922 – Chen Ning Yang was born.

Chen Ning Yang is a Chinese-American physicist who shares the 1957 Nobel Prize in Physics with Tsung-Dao Lee for their contributions to elementary particle physics. They developed a theory where parity is not conserved in weak interactions. It was believed that all forces remained the same under mirror reflection where you would expect identical results if your experimental setup was reflected in a mirror. They found the weak interaction force did not follow parity and their theory was confirmed.

1901 – Charles Brenton Huggins was born.

Charles Brenton Huggins
Charles Brenton Huggins (1901 – 1997)
Nobel Foundation

Huggins was a Canadian-American physician who was awarded half the 1966 Nobel Prize in Medicine for his hormonal treatment of prostate cancer.

He believed that since the prostate gland is controlled by androgen hormones that perhaps blocking those hormones could help treat any cancerous tissue. He originally had the idea of castrating his patients to block these hormones but found the same results could be achieved by using female sex hormones.

1791 – Michael Faraday was born.

Michael Faraday
Michael Faraday (1791 – 1867)

Faraday was an English natural philosopher who made several contributions to the study of electricity and magnetism. He built the first electric motor and discovered electromagnetic induction and of the laws of electrolysis. He also discovered the chemical benzene and introduced the concept of oxidation numbers. The SI unit of capacitance, farad, is named in his honor. The faraday constant is the charge equivalent of a mole of electrons.

1750 – Christian Konrad Sprengel was born.

Sprengel was a German theologian and botanist who was the first to describe the mechanics of pollination in plants. He observed how insects would transfer pollen from the stamen of one flower to the pistil of another. He also coined the term dichogamy to describe the process of maturation of the male and female parts at different times.