1. Chapter 4: Electron Configurations Development of New Atomic Model

2. Properties of Light Light emission/absorption – Electromagnetic spectrum  rays, X rays, UV-visible-IR, microwave/radar, radio waves (TV, FM, Short wave), long waves Light as a wave – Electromagnetic radiation acts like a wave c =  speed of light = (wavelength)(frequency)= 3 x 10 8 m/s – Wavelength is inversely proportional to frequency Interference, diffraction, refraction, & reflection

3. Electromagnetic Radiation Spectrum

4. Wave’s Anatomy

5. Properties of Light, continued Light as a particle – Photoelectric effect Emission of electrons from metal when light hits it Red light’s frequency is too low to excite electrons – Quantum of energy Minimum amount of energy lost/gained by an atom Quantum = small, specific packet of energy – “Photon” : term coined by Einstein Particle of electromagnetic radiation, no mass, 1 quantum Energy of photon = (Plank’s constant)(frequency) E photon = h ; h = 6.626 x 10 -34 Joule second, = 1/sec

6. H-atom Line-Emission Spectrum Electricity through low pressure gas increases atoms’ potential energy (excited states) Atoms have only 1 ground state When atoms return to ground state, they emit that extra energy as electromagnetic radiation Hydrogen shows specific bands ( ) – Balmer series – visible (4 lines/ colors for H) – Lyman series – ultraviolet (5 lines for H) – Paschen series – infrared (3 lines for H)

7. Hydrogen Visible Light Spectrum

8. Quantum Model of the Atom Shows why H atoms emit specific frequencies E photon = E 2 – E 1 = h  – Energy of photon equals difference between excited & ground states – Absorption = added energy moving e - to higher E – Presence of specific bands => fixed energy levels – Electrons only exist is very limited energy states – Niels Bohr’s model: electrons go in defined orbits

9. De Broglie’s Hypothesis Electrons have dual wave-particle nature too Any wave confined to a space has limited Electron beams behaved as waves empirically – Diffraction = bending of waves passing by edges – Interference = overlapping waves or energy – E photon = h  where corresponds to Bohr’s orbits

10. Heisenberg Uncertainty Principle Electrons found by interaction with protons Photons have ~ same energy as electrons Using photons to find electrons kicks e - away THEREFORE… It’s impossible to know both the position & velocity of electron/ particle simultaneously

11. Schrodinger Wave Equation Treats electrons in atoms as waves Only waves of specific energies worked Heisenberg’s Uncertainty Principle plus Schrodinger wave equation  Quantum theory Quantum Theory: mathematical description of wave properties of electrons & other very small particles

12. Quantum Numbers Principal Quantum Number – n = main energy level of the electron Angular Momentum Quantum Number – l = shape of orbital = 0 and n - 1 Magnetic Quantum Number – m = orientation of orbital = + l Spin Quantum Number – s = spin state = clockwise/counterclockwise= + 1/2

13. To Be Continued … Please absorb this information first, then proceed with the PowerPoint entitled “Electron Configuration of atoms & ions” Thank you for your attention Have a good day!