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Energy Level Diagram

Energy Level Diagram. Energy Excited States photon’s path Ground State. Light Emission Light Emission. Light Emission. Quantum Numbers - I. 1) Principal Quantum Number = n Also called the “energy “ quantum number, indicates the approximate distance from the nucleus .

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Energy Level Diagram

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  1. Energy Level Diagram • Energy Excited States photon’s path Ground State Light Emission Light Emission Light Emission

  2. Quantum Numbers - I • 1) Principal Quantum Number = n • Also called the “energy “ quantum number, indicates the approximate distance from the nucleus . • Denotes the electron energy shells around the atom, and is derived directly from the Schrodinger equation. • The higher the value of “n” , the greater the energy of the orbital, and hence the energy of electrons in that orbital. • Positive integer values of n = 1 , 2 , 3 , etc.

  3. Energy-level diagram for the electron in the hydrogen atom.

  4. Transitions of the electron in the hydrogen atom.

  5. 1 n12 1 n22 1 2 2 1 4 2 Using the Rydberg Equation Problem: Find the energy change when an electron changes from the n=4 level to the n=2 level in the hydrogen atom? What is the wavelength of this photon? Plan: Use the Rydberg equation to calculate the energy change, then calculate the wavelength using the relationship of the speed of light. Solution: Ephoton = -2.18 x10 -18J - = Ephoton = -2.18 x 10 -18J - = - 4.09 x 10 -19J h x c E (6.626 x 10 -34Js)( 3.00 x 108 m/s) wavelength = = = 4.09 x 10 -19J wavelength = 4.87 x 10 -7 m = 487 nm

  6. Back to Ch 3

  7. Modern Reassessment of the Atomic Theory 1. All matter is composed of atoms. Although atoms are composed of smaller particles (electrons, protons, and neutrons), the atom is the smallest body thatretains the unique identity of the element. 2. Atoms of one element cannot be converted into atoms of another element ina chemical reaction. Elements can only be converted into other elements in Nuclear reactions in which protons are changed. 3. All atoms of an element have the same number of protons and electrons, which determines the chemical behavior of the element. Isotopes of an element differ in the number of neutrons, and thus in mass number, but a sample of the element is treated as though its atoms have an average mass. 4. Compounds are formed by the chemical combination of two or more elements in specific ratios, as originally stated by Dalton.

  8. Predicted Properties Observed properties (average of Si and Sn) Ge Atomic mass 72 72.61 Density 5.5 g/cm3 5.32 g/cm3 Melting Point 82.5C 93.8C Oxide formula XO2 GeO2 Density of oxide 4.7 g/cm3 4.70 g/cm3 Chloride formula XCl4 GeCl4 Boiling point of chloride 100C 86C

  9. Orbital energies of the hydrogen atom.

  10. Electron Configurations Noble Gases Electron OrbitalsNumber of ElectronsElement 1s2 2 He 1s2 2s22p6 10 Ne 1s2 2s22p6 3s23p6 18 Ar 1s2 2s22p6 3s23p6 4s23d104p6 36 Kr 1s2 2s22p6 3s23p6 4s23d104p6 5s24d105p6 54 Xe 1s2 2s22p6 3s23p6 4s23d104p6 5s24d105p6 6s24f14 5d106p6 86 Rn 1s2 2s22p6 3s23p6 4s23d104p6 5s24d105p6 6s24f145d106p6 7s25f146d10?

  11. Figure 8.12: A periodic table illustrating the building-up order.

  12. Heisenberg Uncertainty Principle • It is impossible to know simultaneously both the position and momentum (mass X velocity) and the position of a particle with certainty !

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