Plutonium is a member of the actinide family. The actinides occur in Row 7 of the periodic table. The periodic table is a chart that shows how chemical elements are related to one another. The actinides get their name from element 89, actinium, which is sometimes considered the first member of the family.he half life of a radioactive element is the time it takes for half of a sample of the element to break down. Consider the isotope plutonium-242, with its half life of 376,300 years. In 376,300 years (one half life), only half of a sample prepared today would still be plutonium-242.