Birth of Chien-Shiung Wu

Wu was born in the town of Liuhe, Taicang in Jiangsu province, China, into a family that highly valued education. Her father, an engineer who encouraged women's equality, was a notable activist during the 1911 revolution that modernized the country.

Understanding of the nucleus

Rutherford et al (1911) determine that a tiny, plus-charged nucleus is at the core of the atom with electrons orbiting in mostly empty space. Marsden (1913) introduces the concept of the isotope to explain elemental variations. First atomic transformations achieved by alpha particle bombardment (1919). 

Discovery of radioactivity

New types of radiation observed by Roentgen (x-rays, 1895) and Becquerel (beta rays, 1898) opened study of atomic transformation via radioactive decay. Key principles are established by M. Curie (process of beta decay, 1902) and Rutherford (principle of the half life, 1904).