Question 19.PS.3: Nuclear Stability For each of these unstable isotopes, write......
Nuclear Stability
For each of these unstable isotopes, write a nuclear equation for its probable mode of decay.
(a) Silicon-32, ^{32}_{14}Si (b) Titanium-43, ^{43}_{22}Ti
(c) Plutonium-239, ^{239}_{94}Pu (d) Manganese-56, ^{56}_{25} Mn
(a) ^{32}_{14}Si → ^{~~0}_{-1}e + ^{32}_{15}P (b) ^{43}_{22}Ti → ^{~~0}_{+1}e + ^{43}_{21}Sc ro ^{43}_{22}Ti + ^{~~0}_{-1}e → ^{43}_{21}Sc
(c) ^{239}_{94}Pu → ^{4}_{2}He + ^{235}_{92}U (d) ^{56}_{25} Mn → ^{~~0}_{-1}e + ^{56}_{26}Fe
Strategy and Explanation Note the ratio of protons to neutrons. If there are excess neutrons, beta emission is probable. If there are excess protons, either electron capture or positron emission is probable. If the atomic number is greater than 83, then alpha emission is probable.
(a) Silicon-32 has excess neutrons, so beta decay is expected.
(b) Titanium-43 has excess protons, so either positron emission or electron capture is probable.
(c) Plutonium-239 has an atomic number greater than 83, so alpha decay is probable.
(d) Manganese-56 has excess neutrons, so beta decay is expected.