Unit 1 - Chemistry Notes
, Bohr Atomic Model
Electromagnetic Spectrum
Rutherford’s Atomic Model
Rutherford’s Atomic Model
● If this model was correct, atoms would emit a continuous spectrum when passed through a
prism/diffraction gradient (appears white)
● Each type of atom emits a unique line spectrum rather than a continuous spectrum.
, What are Photons?
● A quantum is a discrete quantity of energy.
● A photon is a quantum of light radiation.
● The energy of a photon depends on the wavelength or frequency of light.
● Long wavelength = red light
● Short wavelength = purple light
Bohr’s Atomic Model
Ground State Electrons
● While in these energy levels, electrons are very stable, and are said to be in their ground state
● Electrons cannot exist between orbits
● Electrons cannot move into another orbit until more energy is added to the system.
Excited State Electrons
● Electrons can absorb photons of energy (i.e., from an electrical current) and jump up to a
higher energy level resulting in an excited state
● Atoms in an excited state are unstable
● Excited electrons will return to ground state, releasing energy as a photon in the process (with
a particular colour of light).
● Line spectra results when an electron in an excited state emits a photon as it falls to a lower
energy level (also known as an emission spectrum)
, Bohr Atomic Model
Electromagnetic Spectrum
Rutherford’s Atomic Model
Rutherford’s Atomic Model
● If this model was correct, atoms would emit a continuous spectrum when passed through a
prism/diffraction gradient (appears white)
● Each type of atom emits a unique line spectrum rather than a continuous spectrum.
, What are Photons?
● A quantum is a discrete quantity of energy.
● A photon is a quantum of light radiation.
● The energy of a photon depends on the wavelength or frequency of light.
● Long wavelength = red light
● Short wavelength = purple light
Bohr’s Atomic Model
Ground State Electrons
● While in these energy levels, electrons are very stable, and are said to be in their ground state
● Electrons cannot exist between orbits
● Electrons cannot move into another orbit until more energy is added to the system.
Excited State Electrons
● Electrons can absorb photons of energy (i.e., from an electrical current) and jump up to a
higher energy level resulting in an excited state
● Atoms in an excited state are unstable
● Excited electrons will return to ground state, releasing energy as a photon in the process (with
a particular colour of light).
● Line spectra results when an electron in an excited state emits a photon as it falls to a lower
energy level (also known as an emission spectrum)
