Final answer:
Ernest Rutherford, a New Zealand physicist called the 'father of nuclear physics,' greatly advanced the understanding of atomic structure with his nuclear model, proposing a dense nucleus surrounded by electrons, following his famed gold foil experiment in 1909.
Step-by-step explanation:
Ernest Rutherford and His Contribution to Atomic Theory
Ernest Rutherford was a pioneering physicist and is widely known as the 'father of nuclear physics.' His significant experiments marked a turning point in the understanding of atomic structure and the nature of radioactivity. Born in New Zealand in 1871, Rutherford conducted his most notable research in Canada and England, where he became the first Nobel laureate from Oceania in 1908 for his work on the disintegration of elements and the chemistry of radioactive substances.
Rutherford's groundbreaking experiment, conducted in 1909 with colleagues Hans Geiger and Ernest Marsden, involved firing alpha particles at a thin sheet of gold foil. They observed the unexpected scattering of the particles, leading Rutherford to propose the nuclear model of the atom. This model posited a small, dense, positively charged nucleus surrounded by electrons, which drastically altered the earlier plum pudding model proposed by J.J. Thomson.
This discovery of the nucleus and characterization of alpha, beta, and gamma radiation was pivotal in the timeline of atomic theory. It provided the foundation for modern nuclear chemistry and the subsequent work of many other scientists. Rutherford's model serves as a fundamental piece of our current understanding of atomic and nuclear physics, defining the very structure of matter.