x = c E  h (What atoms have to do with it) Chapter 4 H Chem The Atom…cont’d Bohr Model (Proven by looking at Bright-Line Spectra) Therefore These are called: Defined as: Filling order for atoms with more than one electron The observer affects the observed What DeBroglie said Shown with: 1. or 2. The Rutherford Model could not explain… The atom does not collapseThe light emitted by atoms Wave-likeParticle-like (Young…Double Slit) wavelength frequencySpeed of light 3.0 x 10 8 m/s (Planck / Einstein) Quantum of energy Planck’s Constant… 6.6x Js (Photo-electric effect) (photon) Bright-Line Spectra For hydrogen: electrons can have only certain energies colors are emitted when electrons jump from higher to lower energy levels For H: En=En= kJ mole e - n 2 Wave Mechanical Model Heisenberg’s Uncertainty Principle If light has a dual nature…why not matter Schroedinger Electrons are waves (Max Born) …only certain energies allowed Energy levels exist Sub-levels exist spdf orbitals High probability regions in space where the electron is likely to be found (1)(3)(5)(7) Aufbau Pauli Hund’s Config. Orbital Electrons are waves of chance.

Determine the wavelength of light given off when an electron in the 9 th energy level drops to the 8 th energy level in hydrogen

E 9 = kJ/ 81 mol e - = kJ/mol e - E 8 = kJ/ 64 mol e - = kJ/mol e -  E = kJ/mol e - - (-16.2 kJ/mol e - ) = -4.3 kJ/mol e - (4.3 kJ/mol e - )(1 mol e - / 6.02 x e - ) = 7.1 x kJ/ e - energy released→ 7.1 x J = h 1.1 x / s =  (1.1 x / s) = c  = 2.7 x m 7.1 x J/ e - =

Compare the electron orbits of the Bohr model with the electron orbitals of the wave mechanical model Electron orbits in the Bohr Model were paths etched out by the electrons as they circled the nucleus…the electron was viewed as a particle. Electron orbitals are high probability regions in space where the electron is likely to be found. The regions are the result of the application of Schroedinger’s Wave equation to find were the electron position is knowing it possesses a certain amount of energy. There are many places of equal probability; hence a region instead of just one location (the electron cloud!)

Describe an orbital pair. Electrons with the same overall energy spinning in opposite directions.

What does it mean about the positions of the electrons in an atom when the electrons are in the ground state Electrons in the ground state are in there lowest energy configurations.

Write the configuration notation for Cl 1s 2 2s 2 2p 6 3s 2 3p 5 - (chlorine the ion) 6 How many unpaired electrons in the chlorine ion?) zero