May 4, 1870, in Zoetermeer (Netherlands) – October 25, 1926, in Bilthoven (Netherlands)
In 1895, he graduated from the University of Leiden (Netherlands) and the Sorbonne in Paris (France).
His father wanted him to be a lawyer like him and between 1895 and 1900 he worked in a law office in The Hague, however, later he studied mathematical economics in Vienna and Berlin and finally, from 1903, his interest focused on Physics while living in the following eight years between France and Germany.
His great contribution to science was the direct correlation between the charge of the atomic nucleus and the periodic table that was published in the scientific magazine "Nature" on July 20, 1911. He was the first to realize that the number of a element in the periodic table (now known as atomic number) corresponds to the charge of its atomic nucleus. This hypothesis inspired the experimental work of Henry Moseley that quantitatively justified the concept of atomic number which he designated with the letter Z.