2. Created by C. Ippolito October 2006 Electron Configurations Objectives: 1. explain the use of wave-mechanics in atomic theory 2. describe the wave-mechanical model of the atom 3. locate electrons in energy levels, sublevels, and orbitals 4. make orbital diagrams and write electron configurations for elements with atomic numbers from 1 through 38

3. Created by C. Ippolito October 2006 Classical (Newtonian) Mechanics laws of motion developed by Isaac Newton  explains motion of objects on earth and solar system  can explain behavior of some gases  used in Bohr model jumping contradicts smooth continuous changes in kinetic energy

4. Created by C. Ippolito October 2006 Spectroscopy studies the behavior of substances exposed to a continuous exciting energy elements release absorbed energy as light LIGHT  electromagnetic energy in the form of a wave Frequency (f) cycles/second hertz Wavelength (lambda = λ) nanometers Amplitude height of peaks and troughs –velocity = f λ for light velocity = c (3.0 x 10 8 m/s)

5. Created by C. Ippolito October 2006 Line Spectra  unique set of light wavelengths released by excited substance returning to ground state sodium (Na + ) potassium (K + ) barium (Ba +2 ) strontium (Sr +2 ) lithium (Li +1 )

6. Created by C. Ippolito October 2006 Wave (Quantum) Mechanics studies the motion of relatively small particles that travel at relatively fast speeds  Max Planck light energy not released continuously released in small spurts –quantum –quantum – packet of electromagnetic energy –photon –photon – packet of light energy energy is related to frequency of light –f = c/λ c = 3.00 x 10 8 m/s –E = hf –h= 6.6 x 10 -34 j/hz

7. Created by C. Ippolito October 2006 Photoelectric Effect refers to the emission of electrons from certain substances when exposed to light of a particular frequency  Albert Einstein wins Nobel Prize if energy from light is enough to free electron it will; any additional energy does not free additional electrons

8. Created by C. Ippolito October 2006 De Broglie’s Hypothesis combines Einstein and Planck  equation predicts “wave length” of particle with known mass and velocity  combined Planck and Einstein equation E = mc 2 and E = hf so that mc 2 = hf  replaced f with v/λ wave frequency is velocity/wavelength mv 2 = hv/λ  solves for wavelength λ = h/mv Wave-Particle Duality of Nature Wave-Particle Duality of Nature  waves can act like particles and particles can act like waves

9. Created by C. Ippolito October 2006 Measuring Position and Momentum Werner Heisenberg Werner Heisenberg  Heisenberg Uncertainty Principle exact position and exact momentum CANNOT be determined at the same time look at object to see it (light to eyes) –small objects like electron light bouncing off it changes its velocity  can never know where an electron will be or where it is going

10. Created by C. Ippolito October 2006 Schrodinger’s Work Erwin Schrodinger Erwin Schrodinger  electron a wave  develops an equation using quantum number ELECTRON CLOUDdescribes the probable location as an ELECTRON CLOUD Four Quantum Numbers Four Quantum Numbers  used to describe electron behavior in complex atoms

11. Created by C. Ippolito October 2006 Principle Quantum Number (n) describes energy levels used find maximum number of electrons  2n 2 = maximum electrons on level  n 2 = number of orbitals #n2n2 Orbitals2n 2 # of e - 1(1) 2 12(1) 2 2 2(2) 2 42(2) 2 8 3(3) 2 92(3) 2 18 4(4) 2 162(4) 2 32

12. Created by C. Ippolito October 2006 Second Quantum Number (l) sublevels complex atoms with more than one level have higher level divided into sublevels  s – lowest sublevel – “sharp”  p – second sublevel – “principal”  d – third sublevel – “diffuse”  f – fourth sublevel –”fundamental”

13. Created by C. Ippolito October 2006 Third Quantum Number (m) represents subdivisions in the sublevels – orbitalsorbitals  s – one electron pair  p – three electron pairs  d – five electron pairs  f – seven electron pairs

14. Created by C. Ippolito October 2006 Distribution of Electrons Pauli’s Exclusion Principle Pauli’s Exclusion Principle  no two electrons can have exactly the same quantum numbers Fourth Quantum Number –describes magnetic spin Hund’s Rule Hund’s Rule  electrons prefer to occupy an empty orbital before it will occupy one as a pair

15. Created by C. Ippolito October 2006 Diagonal Rule atoms with high atomic numbers do not fill orbitals in order

16. Created by C. Ippolito October 2006 Electron Dot Diagrams chemical properties depend on valance (outermost) electrons  element symbol represents nucleus and all lower level electrons  write out electron configuration  draw dots on sides to represent electrons in orbitals (basically last level of Bohr diagram)

17. Created by C. Ippolito October 2006 Electron Configuration Samples H – 1s 1 He – 1s 2 O – 1s 2 2s 2 2p 4 Ca – 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 Cd - 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10