Francium is extremely rare, and naturally unstable, as it is highly radioactive and the most stable isotope has a half life of 21 minutes. This means that if a francium atom is formed it will almost certainly disappear very, very quickly. At any one time there is only about 25g of naturally occurring francium in the whole of Earth. Its extreme rarity means it is very difficult to find. ...
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...on" is a second full moon in the same month. Usually, there is just one full moon a month. But due to differences between the length of calendar months and the length of the lunar month, a second full moon can occur in the same month. This happens on... more
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... many reasons :This was because francium was a rare substance which only can be extracted out of its ores by radium or astatine. Radium and astatine are very radioactive materials and needed to be dea... more
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