Today in Science History – February 13 – Étienne Geoffroy

Étienne François Geoffroy

Étienne François Geoffroy (1672 – 1731)

February 13 is Étienne François Geoffroy’s birthday. Geoffroy was the French physician best known for compiling the first chemical affinity tables.

Chemists have long known if you mix two substances together, sometimes you get something new. The substances that do form new products are said to share an affinity towards each other. Geoffroy made systematic tests of acting substances on one another and recording the results. He then published tables of substances and the things that share an affinity with them.

This is an example of one of Geoffroy’s tables taken from the 1718 book Memoires de l’Academie Royale des Sciences.

Affinity table

Tables des rapports or Table of Affinities by Étienne François Geoffroy

The top of the table is the substance. Everything underneath in the vertical column is a substance that shares an affinity with the top row substance.

Geoffroy’s tables of chemical affinity were the beginning of understanding chemical bonding. Today, chemical affinity refers to the tendency of atoms to form bonds with other atoms and compounds.

Notable Science History Events for February 13

1990 – Voyager 1 spacecraft returns “Family Portrait”

NASA’s Voyager 1 spacecraft sent back a series of sixty images as it left our Solar System. These images were combined into a single photograph called the Family Portrait. This picture contained the Sun and the planets Neptune, Uranus, Saturn, Venus, Earth and Jupiter and their relative positions. Most of the images were taken with Voyager’s wide-angle camera and the planets themselves were taken with the narrow-angle camera for more detail.

Voyager 1 Family Portrait

Family portrait mosaic photo taken by Voyager 1.

1960 – France tests their first nuclear device.

France tested their first atomic device in the “Gerboise Bleue” test. The device was tested in the Algerian Sahara Desert and had a yield of 70 kilotons. France was the fourth country to develop a nuclear weapon.

1946 – ENIAC first introduced to the public.

J. Presper Eckert and John Mauchly introduced Electronic Numerical Integrator and Computer, or ENIAC, the first general purpose, electronic computer. ENIAC was a giant step forward in computing technology. By doing all functions electronically, it could beat calculation speeds of earlier computing machines. ENIAC was a very large and complex piece of electronics, weighing in at 27 tons and 8.5 ft x 3 ft x 80 ft.

1910 – William B. Shockley was born.

William Shockley (1910 - 1989)

William Shockley (1910 – 1989)
Credit: Stanford News Service

Shockley was an American physicist who shares the 1956 Nobel Prize in Physics with John Bardeen and Walter Houser Brattain for the development of the semiconductor transistor. Transistors are electronic devices used to amplify or switch electronic signals and a basic unit in electronic design. Prior to the semiconductor transistor, transistors were high voltage vacuum tubes. The semiconductor transistor is much smaller, generates less heat and is less expensive.

1909 – Julius Thomsen died.

Julius Thomsen

Julius Thomsen (1826 – 1909)

Thomsen was a Dutch chemist who first suggested the periods in the periodic table should end with valence equal to zero, or the noble gases. He also made contributions to thermochemistry by determining the amount of heat released in 3,500 different chemical reactions.

He is known for the Thomsen-Berthelot principle where chemical changes are accompanied by the production of heat and the process that produces the most heat will be the favored reaction.

1672 – Ètienne-François Geoffroy was born.

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