Francium
Science report
By: Anthony white jnr
Introduction
Francium (pronounced FRAN-see-em;formerly known as eka- caesium and actinitium K) is a chemical element that has the symbol Fr and atomic number 87. It is the second rarest naturally occurring elements after astatine. Francium is a highly radioactive metal that decays into astatine, radium and radon. As an alkali metal, it has one valence electron.
Francium was discovered by Marguerite Perey in France (from which the element takes its name) in 1939. It was the last element discovered in nature, rather than being man made.
Outside the laboratory, francium is very rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays. As little as
20-30g exist at any given time throughout the Earth’s crust; the other isotopes are synthetic. The largest amount ever collected of any isotope was a cluster of about
10,000 atoms (of francium-210) created as an extremely cold gas at Stony Brook in
1997. Francium can be made artificially by bombarding thorium with protons. In a given sample of uranium, there is estimated to be only one francium atom for every 1×1018 uranium atoms. Francium has not yet, as of 2009[update], been synthesized in amounts large enough to weigh. History
As early as 1870, chemists thought that should be an alkali metal after caesium,with an atomic number of 87. It was then referred to by the provisional name eka-caesium. Research teams attempted to locate and isolate this missing element, and at least four false claims were made that the element had been found before an authentic discovery was made. Soviet chemist
D.K.Dobroserdov was the first scientist to claim to have found eka-caesium,or francium.
In 1925, he observed weak radioactivity in a sample of potassium, another alkali metal and concluded that eka-caesium was contaminating the sample.
He then published a thesis on his thoughts of the
By: Anthony white jnr
Introduction
Francium (pronounced FRAN-see-em;formerly known as eka- caesium and actinitium K) is a chemical element that has the symbol Fr and atomic number 87. It is the second rarest naturally occurring elements after astatine. Francium is a highly radioactive metal that decays into astatine, radium and radon. As an alkali metal, it has one valence electron.
Francium was discovered by Marguerite Perey in France (from which the element takes its name) in 1939. It was the last element discovered in nature, rather than being man made.
Outside the laboratory, francium is very rare, with trace amounts found in uranium and thorium ores, where the isotope francium-223 continually forms and decays. As little as
20-30g exist at any given time throughout the Earth’s crust; the other isotopes are synthetic. The largest amount ever collected of any isotope was a cluster of about
10,000 atoms (of francium-210) created as an extremely cold gas at Stony Brook in
1997. Francium can be made artificially by bombarding thorium with protons. In a given sample of uranium, there is estimated to be only one francium atom for every 1×1018 uranium atoms. Francium has not yet, as of 2009[update], been synthesized in amounts large enough to weigh. History
As early as 1870, chemists thought that should be an alkali metal after caesium,with an atomic number of 87. It was then referred to by the provisional name eka-caesium. Research teams attempted to locate and isolate this missing element, and at least four false claims were made that the element had been found before an authentic discovery was made. Soviet chemist
D.K.Dobroserdov was the first scientist to claim to have found eka-caesium,or francium.
In 1925, he observed weak radioactivity in a sample of potassium, another alkali metal and concluded that eka-caesium was contaminating the sample.
He then published a thesis on his thoughts of the