Ernest Rutherford made several groundbreaking discoveries in the field of atomic and nuclear physics:

• He discovered that radioactive emissions consist of two distinct types of radiation, which he named alpha and beta rays

• He proposed the laws of radioactive decay and identified alpha particles as helium nuclei

• Most famously, through his gold foil experiment conducted by Hans Geiger and Ernest Marsden under his direction, Rutherford discovered the atomic nucleus in 1911. This showed that atoms have a small, dense, positively charged nucleus containing most of the atom's mass, surrounded by mostly empty space

• He postulated that the hydrogen nucleus (proton) is a fundamental building block of other nuclei and named this particle the proton in 1920

• Rutherford also theorized the existence of neutrons, which was later confirmed by his associate James Chadwick in 1932

• Additionally, he discovered the radioactive element radon and demonstrated that radioactivity is a natural transmutation of elements

These discoveries laid the foundation for modern nuclear physics and atomic theory, earning him the Nobel Prize in Chemistry in 1908