Ernest Rutherford (1871-1937), Baron Rutherford of Nelson, a British physicist, worked out the nuclear theory of the atom in 1911. Earlier, he had published his theory of atomic transmutation. He also discovered alpha and beta rays and protons. Because of Rutherford's many contributions to science, he has been called the father of nuclear science.
In the nuclear theory of the atom, Rutherford discarded the notion that atoms were like solid "building blocks." He explained that they are constructed much like the solar system. That is, a heavy part, called the nucleus, forms the center of each atom. Particles of negative electricity, called electrons, form the outer part of the atom, most of which consists of space. Niels Bohr later combined the nuclear theory with the quantum theory in the Bohr theory of atomic structure.
In 1902, Rutherford published his theory of atomic transmutation. The theory explains that radioactive elements give off electrically charged particles known as alpha and beta rays. This process changes the parent (original) atom into a daughter atom. Because of the changes, the new atom is in the form of a different chemical element. This achievement won Rutherford the 1908 Nobel prize in chemistry. Rutherford produced the first man-made atomic disintegration.
