## General, Organic, and Biological Chemistry: Structures of Life (5th Edition)

a) curium-243: $^{243}_{96}$Cm --> $^{239}_{94}$Pu + $^4_2$He b) $^{252}_{99}$Es --> $^{248}_{97}$Bk + $^4_2$He c) $^{251}_{98}$Cf --> $^{247}_{96}$Cm + $^4_2$He d) $^{261}_{107}$Bh --> $^{257}_{105}$Db + $^4_2$He
An alpha particle always equals a Helium atom, or $^4_2$He. When alpha decay takes place with an isotope, the resulting product is a new isotope of a different element, plus one alpha particle. To balance the equation, and find the new atom/isotope, you must subtract 4 from the mass number of the original isotope and 2 from the atomic number of the original isotope, which will give you a new element, plus an alpha particle.