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How did Niels Bohr connect the periodic table to electron structure?

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Periodic table of the elements with color-coded categories and labeled element groups, showing atomic numbers, symbols, and basic information for each chemical element. — periodic table Modern version of the periodic table of the elements. To learn an element's name, atomic number, electron configuration, atomic weight, and more, select one from the table.

Niels Bohr’s 1913 Bohr model was a foundational step in connecting the periodic table to atomic structure by introducing the concept of quantized electron orbits. By proposing that electrons occupy specific, discrete energy levels (or shells) around the nucleus, Bohr provided the framework for understanding how atoms are built up as electrons fill these shells.1234

While the original Bohr model was limited in its ability to explain multielectron atoms, it established the essential idea that an atom's chemical properties are determined by its outermost, or valence, electrons. This concept explains why elements in the same column of the periodic table exhibit similar chemical behaviors: they share analogous valence electron configurations.45

The full connection to the periodic table was later solidified by incorporating the Pauli exclusion principle, which dictates how electrons fill available orbitals. Together, these developments transformed the periodic table from an empirical observation into a system based on the underlying electronic structure of atoms.625