Chapter 13 Section 3 -Quantum mechanical model grew out of the study of light -light consists of electromagnetic radiation -includes radio and UV waves, X-rays, gamma rays, visible light -these waves move at a constant speed of 3.00X10 8 m/s or 3.00X10 10 cm/s -this is the speed of light (c)

origin

amplitude- height of a wave from the origin to the crest wavelength- (λ) - distance between two adjacent crests (units= m, cm, nm) frequency- (ν) - # of wave cycles that pass through a given point per unit time -(units= cycles/sec or 1/s or s -1 or hertz- Hz) -each complete wave cycle begins at the origin and returns to the origin

-frequency is directly proportional to the speed at which the wave is traveling- the faster the wave, the higher the frequency -frequency and wavelength are inversely proportional

visible light- light that can be seen by the human eye -wavelength determines the color of the visible light -can see colors when white light is passed through a prism -red, orange, yellow, green, blue, indigo, violet -red light has the longest wavelength (750nm) -violet has shortest (400nm)

-electrons emit light when they are excited by the passage of an electric discharge through an element atomic emission spectrum- range of wavelengths emitted by a particular element that can be used to identify an element Ex- neon lights

Formulas c = νλ c = speed of light (3.00 x 10 8 m/s or 3.00X10 10 cm/s) ν = frequency (1/s, s -1, Hz) λ = wavelength (m, cm, nm(10 -9 )) λ = c/νν = c/λ Book problems

Max Planck -found that energy of a body changes in small discrete units E = hν E = energy in joules (J) h = Planck’s constant = x J∙s ν = frequency (1/s, s -1, Hz) v = E/h

photons- particles of light photoelectric effect- metals emit electrons when light shines on them *especially the alkali metals -used in solar calculators