Chemistry – Chapter 4

Rutherford’s Atomic Model

Wave-like Characteristics of Light  All forms of electromagnetic radiation form the electromagnetic spectrum = continuous.  All forms of electromagnetic radiation move at a constant speed = 3.00 X 10 8 m/s  Properties include – frequency and wavelength  Formula – c = ʎv  c= speed of light, a constant (3.00 x 10 8 m/s)  ʎ = wavelength (m)  v = frequency, in units of hertz (Hz, sec -1)

Electromagnetic Spectrum

Wavelength

Relationship Between Wavelength and Frequency

Visible Light

Relationship Between Frequency and Energy E = hv E = energy v = frequency h = x Jxs (Planck’s constant)

Particle Theory of Light  Photoelectric effect – light is emitted in small specific amounts called quanta.

Photoelectric Effect  Quantum – the minimum amount of energy lost or gained by an atom.  Aka - photon

Absorption and Emission  If a photon’s frequency is below the minimum requirement, electrons in the atom cannot move.  Different metals have different minimum frequencies.  Ground state –  Excited state -