Electrons Negative charge e- Located in the electron cloud far from the nucleus Have mass, but it is negligible Also have wave-like properties

Bohr Model of the atom Bohr model: e- move in fixed orbits around the nucleus

Wave-Mechanical Model of the atom Wave-mechanical model: e- move in areas called orbitals An orbital is a region where an e- is likely to be found

Electrons have Electron S in their lowest possible energy state are in the GROUND STATE

Electron S in a HIGHER possible energy state are in the EXCITED STATE

Ground State Excited State e-

For an e- to jump from the ground state to the excited state, it must absorb energy (a photon of light) When an e- falls back down from excited state to ground state, it releases energy (a photon of light)

Fluorescent and neon lights are caused by excited e- returning to ground state

Ordinary light is seen by our eyes as a continuous spectrum

The visible light produced by e- falling back to ground state is called a bright line spectrum Light is emitted only at certain wavelengths

Each element has its own distinct bright line spectrum Bright line spectra can be used to identify elements, by comparing the spectral lines to known spectra