Below is a table showing the steps of decay of uranium-238. Notice that the first step has an extremely long halflife but remaining steps have a relatively short halflives.  For example, half of a sample of Th-234 decays to Pa-234 in 24 days. This means that the transitory radioactive elements do not live long but contribute the greatest health hazard to people working in Uranium mines.

Sometimes there are alternative paths taken.  Notice radon decays to polonium in the seventh step.

Here is the same for U-235. Notice the chain finishes in a different isotope of lead!

Diagrams thanks to Wikipedia