Whose work first separated uranium and its decay products into distinct radioactive elements?

Ernest Rutherford and Frederick Soddy developed the theory of radioactive decay between 1902 and 1903. They showed that radioactive atoms change into other elements at a measurable rate, a revolutionary idea for chemistry. Their work explained decay chains involving uranium, thorium and radium and introduced the concept of half-life. This was a major step toward nuclear chemistry and modern atomic science.