What is the electron capture reaction for astatine-200 in terms of the individual steps?
1 Answer
Electron capture is when an inner-core electron (
#""_(-1)^(0) e + ""_1^1 p -> ""_(0)^(1) n#
A neutron can then combine into an isotope to give:
#""_(Z)^(A) X + ""_(0)^(1) n -> ""_(Z)^(A+1) X#
And a proton that was used up in the process is lost as follows:
#""_(Z)^(A+1) X -> ""_(Z-1)^(A) X + ""_(1)^(1) p#
Astatine-200,
#""_(85)^(200) "At"#
So, this isotope takes in an electron to lose a proton and gain a neutron as described above:
#""_(-1)^(0) e + cancel(""_1^1 p) -> cancel(""_(0)^(1) n)#
#""_(85)^(200) "At" + cancel(""_(0)^(1) n) -> cancel(""_(85)^(201) "At")#
#cancel(""_(85)^(201) "At") -> ""_(84)^(200) "Po" + cancel(""_(1)^(1) p) + nu#
Overall, we then get...
#color(blue)ul(""_(85)^(200) "At" + ""_(-1)^(0) e -> ""_(84)^(200) "Po" + nu)#
And with