Alpha and bta dcay quation practic Introduction Alpha and bta particls may b rprsntd in quations in svral diffrnt ways. Diffrnt xam boards hav thir own prfrnc. For xampl: Alpha Bta α β alpha bta Dspit diffrnt ways of writing thm, you nd to know what ach particl is in ordr to mak sns of things. Alpha particls ar oftn calld a hlium- nuclus as thy ar idntical to th nuclus of a hlium- atom (hlium s most common isotop). Thy consist of two protons and two nutrons. Bta particls com in two forms, th on indicatd abov is a ngativly-chargd vrsion (or bta-minus particl). Thr is also a bta-plus form. Both ar quit surprising as, lik alpha particls, thy com from th nuclus of an unstabl radioactiv atom. Bta-minus particls ar fast-moving lctrons, mittd whn a nutron dcays into a proton in th nuclus. www.tachitscinc.co.uk 18 3599 Pag 1 of 6
Alpha and bta dcay quation practic Alpha dcay Whn a radioactiv nuclus mits an alpha particl, th dcaying nuclus obviously bcoms lightr as it loss four particls: two protons and two nutrons. All alpha dcay quations thrfor follow this simpl pattrn: th atomic numbr (or proton numbr) rducs by two, th mass numbr rducs by four (sinc th nuclus loss two protons and two nutrons)..g. 19 radon 15 8 polonium + Somtims quations will b writtn only with th chmical symbols of th atoms, in this cas: 19 Rn Notic th rduction in th atomic numbr from to 8. Th two lost protons ar of cours in th alpha particl ( ). Manwhil, th mass numbr has droppd by four, from 19 to 15. 15 8 For alpha dcays, you must rmmbr that th mass numbr must drop by four and th atomic numbr by two. Po + Complt th following quations by writing in th missing numbrs: 3 Th Ra Rn + 16 8 Rmmbr to chck that things mak sns! Lik any quation, things must balanc. So add up th mass numbrs on th right, thy should qual what you bgan with. Do th sam for th atomic numbrs. Somtims you will b xpctd to balanc th dcay quations going th othr way. Try ths: Bi 8 81 Tl + Ac 1 Fr + 9 You may vn hav to tackl a combination of both: 9 3 37 Np 91 Pa + 13 8 www.tachitscinc.co.uk 18 3599 Pag of 6
Alpha and bta dcay quation practic Bta dcay Whn a radioactiv nuclus mits a bta particl, th dcaying nuclus onc again changs, but nowhr nar as significantly as during alpha dcay. As mntiond bfor, bta dcays com in two typs. At GCSE it is usual just to considr bta-minus dcay. Bta-minus dcay happns whn a nutron changs into a proton in th nuclus, spitting out an lctron (th bta particl) in th procss. This rsults in a mor stabl nuclus. Now you should know that th nuclus only contains protons and nutrons (no nutrons in th cas of th lightst isotop of hydrogn). Thr ar, of cours, no lctrons in any nuclus. It is byond th scop of a GCSE cours to go into how a nutron can chang into a proton and mit an lctron (bta particl). For now, just know that it can happn! In th procss of bta dcay, only th tiny bta particl is mittd from th nuclus, no protons or nutrons lav. This mans th mass numbr of th nuclus bfor and aftr bta dcay rmains xactly th sam. This is clarly worth rmmbring! For bta dcays, you must rmmbr that mass numbr is unchangd aftr th dcay. Manwhil, sinc a nutron changs into a proton, th proton numbr (atomic numbr) must incras by on. Again, you nd to rmmbr this and it will always b th sam for bta-minus dcay..g. 1 6 carbon 1 7 nitrogn + or 1 6 C 1 7 N + Notic that th mass numbr (top row) is unchangd and th atomic numbr (bottom row) gos up by on. Th bta particl (lctron) is shown as having a ngativ proton numbr bcaus it has th opposit lctric charg. As with alpha dcay quations, notic that th top row adds up to th sam thing on both sids of th quation. For bta(-minus) dcays, rmmbr only that th atomic (proton) numbr incrass by on aftr th dcay. Complt th following quations by writing in th missing numbrs: 6 Cu Ni + 9 5 Na Mg + 11 56 Mn F + 5 www.tachitscinc.co.uk 18 3599 Pag 3 of 6
Alpha and bta dcay quation practic As with alpha dcay quations, always chck that th mass numbrs and proton numbrs add up on th top and bottom rows. Now try ths: B 5 B + F N + Br 36 Kr + And thn ths: 15 Sb 5 T + Fr 37 Np + Finally, writ th full dcay quations for th following: 1. Ra into Rn by alpha dcay.. 79 Au into Hg by bta dcay. 15 3. Bi into Po by bta dcay, which thn, in turn, alpha dcays into Pb. www.tachitscinc.co.uk 18 3599 Pag of 6
Alpha and bta dcay quation practic Answrs Alpha: 3 Th 8 Ra Rn + 16 8 1 8 1 Bi 8 81 Tl + 5 89 Ac 1 Fr + 33 9 9 38 9 3 37 Np 33 91 Pa + 13 8 9 8 Bta: 6 Cu Ni + 9 6 3 5 Na Mg + 11 5 1 56 Mn F + 5 56 6 B 5 B + 9 F N + Br Kr + 35 36 15 51 Sb 15 5 T + Fr 37 9 37 Np + Unguidd: 1. Ra 18 Rn +. 79 Au 8 Hg + 15 3. Bi 15 8 Po + 15 11 8 thn Pb 8 + Taching nots This worksht is dsignd to giv you furthr practic on th compltion and writing of both alpha and bta radioactiv dcay quations. It assums you hav bn givn a rasonabl introduction into both procsss by your tachr or through prsonal study using a txtbook or wbsit. Th last pag is a compilation of th practic quations from th worksht. www.tachitscinc.co.uk 18 3599 Pag 5 of 6
Complt th following quations. Alpha and bta dcay quation practic 3 Th Ra Rn + 16 8 6 Cu Ni + 9 56 Mn F + 5 5 Na Mg + 11 Bi 8 81 Tl + Ac 1 Fr + 9 9 3 37 Np 91 Pa + 13 8 B 5 B + F N + Br 36 Kr + 15 Sb 5 T + Fr 37 Np +. Ra into Rn by alpha dcay. 5. 79 Au into Hg by bta dcay. 15 6. Bi into Po by bta dcay, which thn, in turn, alpha dcays into Pb www.tachitscinc.co.uk 18 3599 Pag 6 of 6