Atoms

Rutherford's Alpha-Scattering Experiment

Bombarding a thin gold foil with alpha particles revealed that an atom has a tiny, dense, positively charged nucleus at its center, surrounded by empty space.

Bohr's Postulates

Bohr proposed that electrons revolve only in specific non-radiating orbits called stationary states where their angular momentum is quantized as integral multiples of h/(2π).

Atomic Spectra

When an electron transitions from a higher energy level to a lower one, it emits a photon of specific frequency, producing discrete spectral lines characteristic of the element.

Hydrogen Spectrum Series

The spectral lines of hydrogen are categorized into series—Lyman (ultraviolet), Balmer (visible), Paschen, Brackett, and Pfund (infrared)—based on the lower energy level involved in the transition.

Radius and Velocity in Bohr's Model

The radius of the nth orbit is directly proportional to n squared (r ∝ n²), while the velocity of the electron in the nth orbit is inversely proportional to n (v ∝ 1/n).