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# Isotopes such as $^{26} \mathrm{Al}$ (half-life: $7.2 \times 10^{5}$ 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 $\beta^{+}$ emission or electron capture. Write the equations for these two nuclear transformations.(b) The earth was formed about $4.7 \times 10^{9}(4.7 \text { billion) years ago. How old was the earth when } 99.999999 \% \text { of the }$ 26 Al originally present had decayed?

## a) $26 \mathrm{Al} \rightarrow_{12}^{26} \mathrm{Mg}+_{+1}^{0} \mathrm{e}$, $_{13}^{26} \mathrm{Al}+_{-1}^{0} \mathrm{e} \rightarrow_{12}^{26} \mathrm{Mg}$b) $1.7 \times 10^{7}$ years

#### Topics

Nuclear Chemistry

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##### Stephanie C.

University of Central Florida

##### Allea C.

University of Maryland - University College

### Video Transcript

but the action the presents the radioactive decay off mercury quantity into platinum 1 76 as follow with the release off alpha particle. The body, it shows the decay off. Give Jim 90 in tow. Zirconium 90 part C shows the radioactive decay off tourney, um 2 32 in tow. We don't do it. The reaction also represents the decay from they don't tow, tow it in tow, active him to do it. But the last part shows the gay off me or 19 in tow floor in 19.

University of New Mexico

#### Topics

Nuclear Chemistry

##### Stephanie C.

University of Central Florida

##### Allea C.

University of Maryland - University College