evolution of atomic structure. dalton 1805 billiard ball model composed of indestructible,...
TRANSCRIPT
Evolution of Atomic Structure
Dalton 1805
• Billiard Ball Model• Composed of
indestructible, indivisible atoms
• Identical for each element but different from other elements
Thompson 1904
• Raisin Bun Model• Atoms have electrons
embedded in a positive material
Rutherford
Nuclear Model• Atom is composed of a
tiny nucleus and orbiting electrons
• Most of the atom is empty space
• Very small electrons occupy most of the space
• Nucleus is composed of protons and neutrons
Key experiment:Gold Foil Experiment
http://www.mhhe.com/physsci/chemistry/essentialchemistry/flash/ruther14.swf
http://micro.magnet.fsu.edu/electromag/java/rutherford/
Quantum Theory
Hot Body Spectrum
Continuous Spectra?
• Mathematical model’s could not explain the entire distribution of light at the time
• Max Planck surmised that the spectra was not continuous but rather had steps
Photoelectric Effect
• When specific wavelengths of light hit some metals electrons will be displaced
• The intensity of the light did not effect the current produced
• The wavelength of light did effect the current
Bohr Model
Quantized Model Electrons exist in
exact orbits/shells The distance from the
nucleus of each orbit is quantized
Used Balmer’s line spectra
http://www.upscale.utoronto.ca/PVB/Harrison/BohrModel/Flash/BohrModel.html
Types of Spectra
Line
Spe
ctra
Bohr’s Postulates
Bohr’s First PostulateBohr’s First PostulateElectrons do not radiate energy as they orbit the nucleus. Each orbit corresponds to a state of constant energy (called a stationary state).
Bohr’s Second PostulateBohr’s Second PostulateElectrons can change their energy only by undergoing a transition from one stationary state to another.
Quantum Numbers
Principal Quantum Number
• Main Shell
Secondary Quantum Number
• The secondary quantum number relates primarily to the shape of the electron orbit. The number of values for l equals the volume of the principal quantum number.
Magnetic Quantum Number
• The magnetic quantum number, ml, relates primarily to the direction of the electron orbit. The number of values for ml is the number of independent orientations of orbits that are possible.
• Values of ml range from –l to +l
Spin Quantum Number
• The spin quantum number, ms, relates to a property of an electron that can best be described as its spin. The spin quantum number can only be 1/2 or1/2 for any electron.
p. 162 – 184
p. 166 # 1-6, 11
p. 173 #1-5
p. 180 # 1-4, 7, 9, 10
p. 184 # 1-6