Chapter 4 The Bohr Model of the Atom

Chapter 4 The Bohr Model of the Atom Part 1

Visible Light

Niels Bohr • In 1913 Bohr published a theory about the structure of the atom based on an earlier theory of Rutherford's. • Bohr expanded upon this theory by proposing that electrons travel only in certain successively larger orbits.

Bohr Model of the Atom The Bohr Atom • Electrons orbit the nucleus in orbits that represent specific quantities of energy. • The energies of the electrons in the atom are quantized. • Only certain electron orbits (energy levels) are allowed.

Niels Bohr • Bohr also described the way atoms emit radiation by suggesting that when an electron jumps from an outer orbit to an inner one, that it emits light.

Ground State • The lowest energy state of an atom.

Excited State • Any energy state of an atom that is higher in energy than the ground state.

Energy Absorbed

Absorption (Dark – Line) Spectra

Energy Emitted Electron jumps to a lower orbit

Emission (Bright – Line) Spectra

Emission Spectra

The lines present in an emission spectrum are the lines missing in an absorption spectrum.

Describe the process that occurs inside atoms that produces the spectra? • Energy is absorbed by the atom. • The electrons jump into higher orbits and the atom becomes “excited”. • The electrons return to their original orbits and the atom returns to the ground state. • The electrons release energy in the form of visible light. • The specific energies (wavelengths, frequencies) of visible light absorbed and released produce the spectra.