1、CHEMISTRY 161Chapter 7 Quantum Theory and Electronic Structure of the Atom www.chem.hawaii.edu/Bil301/welcome.html,1. Structure of an Atom,subatomic particles,electrons,protons,neutrons,mass number,atomic number,18 neutrons,2. What forces combine atoms to molecules?,e-,classical physics predicts tha
2、t electron falls into nucleus,1. Why are atoms stable?,2. Properties of Waves,Intensity,Distance,.,.,direction of propagation,l,wavelength m,amplitude,Intensity,Time,.,.,direction of propagation,Period s,T,Frequency s-1,1 Hz = 1 s-1 Hertz,Frequency and Wavelength,wavelength,frequency,speed of radiat
3、ion,meter (m),Hz or s-1,m s-1,LONG WAVELENGTH, LOW FREQUENCY,SHORT WAVELENGTH, HIGH FREQUENCY,Which wave has the longest wavelength?,The number of waves passing a given point per second is:,2 = THE FREQUENCY,1 = THE SPEED,3 = THE WAVELENGTH,light can be described as a wave,James Maxwell,POSTULATE,vi
4、sible light consist of electromagnetic waves,speed of propagation (speed of light)c = 300,000 ms-1,light has two components Electric field component Magnetic field component,ELECTROMAGNETIC SPECTRUM,INCREASING FREQUENCY,Which color has the higher frequency?,1 = orange,2 = blue,ln = c,Wavelength l (n
5、anometers),VISIBLE SPECTRUM,The wavelength of the yellow light from a lamp is 589 nm.,What is the frequency of the radiation?,Max Planck,POSTULATE,h is Plancks constant h = 6.626 x 10-34 J s,Li,Na,K,Different atoms emit distinct light,Plancks Quantum Theory,HEAT,ANALYSE,Heat hollow object,CLASSICAL
6、any amount of energy can be emitted or absorbed,NON-CLASSICAL energy can be emitted or absorbed only in discrete quantities (little packages),energy is not continuous,QUANTUM smallest amount of energy which can be absorbed/ emitted,Einitial,Efinal,ABSORPTION OF A PHOTON,atoms and molecules absorb di
7、screte photons (light quanta),THE PHOTOELECTRIC EFFECT,light,electron,metal,shine light on a piece of metal and electrons are emitted,electrons are emitted only if the frequency of the light,is greater than a minimum value depending on the metal,3. Properties of Photons,THE PHOTOELECTRIC EFFECT,Albe
8、rt Einstein,Electromagnetic radiationcan be viewed as a streamof particle-like units calledphotons,POSTULATE,de Broglie,Duality of Wave and Corpuscle,light has properties of a wave and of a particle,SUMMARY,1. light can be described as a waves of a wavelength and frequency,2. light can be emitted or absorbed only in discrete quantities (quantum package - photon),3. duality of wave and corpuscle,HomeworkChapter 7, pages 245-252problems,
