Question

Activity 27-7. Nuclear decays II [Accompanies Section 27-6] (a) Rank the following decays in order of the change in atomic number Z that occurs in the decaying nucleus, from most positive (greatest increase in Z) to most negative (greatest decrease in Z). If any two decays cause the same change in Z, state this. Explain how you made your ranking. (i) Alpha decay (emission of a He nucleus of charge +2e) (ii) Beta-minus decay (emission of an electron of charge -e and an antineutrino) (iii) Beta-plus decay (emission of a positron of charge +e and a neutrino) (iv) Gamma decay (emission of a photon) (b) Fill in the blanks with the phrase alpha decay, the phrase beta-minus decay, the phrase beta-plus-decay, the phrase gamma decay, or the phrase don't know. (i) If a nucleus is in an excited state, one common way for it to return to its ground state while retaining the same number of protons and neutrons is via (ii) If a nucleus can increase its stability by converting one proton into a neutron, it will undergo (iii) If a nucleus can increase its stability by converting one neutron into a proton, it will undergo (iv) Very large nuclei with more than 82 protons, such as radon, radium, and thorium, can increase their stability by becoming smaller. One common way in which this can happen is

Answer 1

and ci) (0) In order of change in atomic number Z, ice from most positive ( greatest increase inz) to the most negative a greatest decoease) is: (ii) B-decay; (iv) Y- decay; (iiip-decay's Alpha decay. in short (i), (iv), (ii), (i) answer. >Because in ß decay, the mucleon number (A = Z+N) remains the same. but one neubon converts to prolon and (A= (2+. - (Z+1)+(NF-1) = Z HN) atomic number increases by → In r-decay, the nucleus just comes down from excited state to the grouend state by emitting photon and hence atomic number doesn't change doesn't chang. meaning increase by Zero unit thus one unit an a

Time z to Nel A = (2-1) + (N+12=N+ Z remains the same. one also A=ZIN Just like polecay, in ptdecay remains the same. but this decreases to (Z-1) and New creases so that Hence atomic number decreases by! & units. taken → In the a-dechay, two protons are out I along with Ostwo neutšers) hence the atomic number decreases toy - 2 units (b) ciz Gamma decay. (ii) Beta-plus-decay (iii) Beta - neinus - decay (iv) Alpha-decay. The explanations to these is given in (a)