11.1.11—Α- and β-decay by a radioactive decay equation of the form UT h92 238 90 234

An alpha decay lowers A by 4 and Z by 2; beta-minus raises Z by 1; beta-plus lowers Z by 1, with A unchanged. Gamma leaves A and Z unchanged.

Balance the daughter nuclide first, then include the emitted particle and check both A and Z totals.

^238_92U→^234_90Th+^4_2He is balanced for alpha decay; β− changes a neutron-rich nucleus’s Z upward by one.

Beta decay changes element identity through Z, while gamma decay changes only nuclear energy state, not the element.