Isotopes such as 26 Al (half-life: 7.2 x 10³ years) are believed to have been present in our solar system as it formed, but have since decayed and are now called extinct nuclides. (a) 26 Al decays by 3+ emission or electron capture. Write the equations for these two nuclear transformations. (b) The earth was formed about 4.7 ×10º (4.7 billion) years ago. How old was the earth when 99.999999% of the 26 Al originally present had decayed?
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Following the somewhat serendipitous discovery of radioactivity by Becquerel, many prominent scientists began to investigate this new, intriguing phenomenon. Among them were Marie Curie (the first woman to win a Nobel Prize, and the only person to win two Nobel Prizes in different sciences—chemistry and physics), who was the first to coin the term “radioactivity,” and Ernest Rutherford (of gold foil experiment fame), who investigated and named three of the most common types of radiation. During the beginning of the twentieth century, many radioactive substances were discovered, the properties of radiation were investigated and quantified, and a solid understanding of radiation and nuclear decay was developed.