Chapter 1
The Beginnings
Antoine-Henri Becquerel, director of Paris' Museum of Natural History; responsible for large collection of luminescent minerals that his father had assembled. When these minerals absorbed light, they would emit light of wavelengths (colors) different from the original source.
Luminescence: while the incident light is present
Fluorescence: continues to emit the light even when the incident light (e.g., sunlight) is removed
Phosphorescence: if the luminescence continues
Becquerel started testing various minerals.
Uranium: named in 1789 after the newly discovered planet Uranus; it was a heavy metal found mainly in European mines; it was used to color ceramics and glass; no evidence there was anything special about it
Becquerel discovered that uranium phosphoresced even without an antecedent light; laying a piece of uranium on a photograhic plate in a darkened drawer; some time later, the developed play would reveal the outline of the mineral shape that had been placed there.
Concept of ionizing rays.
Chapter Two
The Curies
Madame Curie tested uranium compounds for emitting ionizing rays (which she called "activity"): the ability of an element to emit ionizing rays depended directly upon the amount of uranium it contained, rather than on its physical or chemical state. - p. 24
Madame Curie decided to test many minerals looking for ionizing rays. Only two metals she tested gave off invisible ionizing rays: uranium and thorium.
Thorium, a mineral first identified in Norway, was named in 1829 after the Norse god Thor.
Curie named this "power": "radio-activity," in 1898. These rays became generally known as "Becquerel rays," a term first used by the Curies in the same year.
"If radioactivity was a property of certain elements regardless of their physical or chemical state, radioactivity must be a property of the atoms of these elements, an atomic property. At that time it was considered very important to distinguish between atomic properties and molecular properties. Atomic properties were presumed to be unchanging characteristics of individual atoms, while molecular properties characterized combinations of atoms, such as chemical compounds.."
"As an atomic property, radioactivity would take its place among the established atomic properties of weight, spectra, and valence."
"Looking back, it is tempting to read more into the term atomic property than it meant at the time, and Marie Curie herself encouraged this extrapolation. Becquerel had already concluded that radioactivity was a property of a specific element. Curie went one step further by stating that radioactivity was an atomic property. This insight was significant. However, the term atomic in 1898 did not have the associations it acquired after the discovery of atomic transmutation, especially after atomic reactors and bombs entered the picture." -- p. 26
New Elements! -- p. 26
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