1. Electronic Structure

3. Wave-Particle Duality Wave-Particle Duality JJ Thomson won the Nobel prize for describing the electron as a particle. His son, George Thomson won the Nobel prize for describing the wave-like nature of the electron. The electron is a particle! The electron is an energy wave!

4. The Wave-like Electron Louis deBroglie The electron propagates through space as an energy wave. To understand the atom, one must understand the behavior of electromagnetic waves.

5. Electromagentic Waves Electromagentic Waves Waves have three primary characteristics: Waves have three primary characteristics: 1. Wavelength (λ) – distance between two consecutive peaks or troughs in a wave 2. Frequency ( ט ) – number of waves per second that pass a given point in space 3. Speed of light (c) – equal to the wavelength multiplied by the frequency (c =λ ט ) c=3.0x10 8 m/s

6. Electromagnetic Radiation Electromagnetic Radiation Radiant energy that exhibits wavelike behavior and travels through space at the speed of light in a vacuum Radiant energy that exhibits wavelike behavior and travels through space at the speed of light in a vacuum Wave energies are classified by their wavelength and frequency in the electromagnetic spectrum Wave energies are classified by their wavelength and frequency in the electromagnetic spectrum Spectrum of a substance – the wavelength emitted or absorbed unique to the substance Spectrum of a substance – the wavelength emitted or absorbed unique to the substance Electromagnetic Spectrum

7. E = h E = h E = Energy, in units of Joules (kg·m 2 /s 2 ) h = Planck’s constant (6.626 x 10 -34 J·s) = frequency, in units of hertz (hz, sec -1 ) = frequency, in units of hertz (hz, sec -1 ) The energy (E ) of electromagnetic radiation is directly proportional to the frequency ( ) of the radiation. Energy is quantized into “packets” of energy called quantums Energy is quantized into “packets” of energy called quantums

8. LongWavelength= Low Frequency = Low ENERGY ShortWavelength= High Frequency = High ENERGY Wavelength Table

9. BOHR – began answering the Dilemma of the Atom Treat electrons as waves Treat electrons as waves As the electron moves toward the nucleus, the wavelength shortens As the electron moves toward the nucleus, the wavelength shortens Shorter wavelength = higher energy Shorter wavelength = higher energy Higher energy = greater distance from the nucleus Higher energy = greater distance from the nucleus Treat electrons as waves Treat electrons as waves As the electron moves toward the nucleus, the wavelength shortens As the electron moves toward the nucleus, the wavelength shortens Shorter wavelength = higher energy Shorter wavelength = higher energy Higher energy = greater distance from the nucleus Higher energy = greater distance from the nucleus

10. Bohr’s “Planetary” Model of the Atom Neils Bohr (Danish Physicist), 1913 Neils Bohr (Danish Physicist), 1913 Similar to Rutherford’s model Similar to Rutherford’s model New Idea: Electrons are arranged in concentric circular paths (orbitals) around the nucleus New Idea: Electrons are arranged in concentric circular paths (orbitals) around the nucleus Orbitals are known to have certain amounts of energy “ENERGY LEVELS” Orbitals are known to have certain amounts of energy “ENERGY LEVELS” http://images.search.yahoo.com/search/images/

11. Bohr’s Theory Energy exists in the atom and increases like a ladder as you move from orbital to orbitalEnergy exists in the atom and increases like a ladder as you move from orbital to orbital Electron transitions involve jumps of definite amounts of energy.Electron transitions involve jumps of definite amounts of energy. This produces bands of light with definite wavelengthsThis produces bands of light with definite wavelengths

12. Electron Movement Ground State – electrons in their lowest possible energy level Excited State – electrons gain energy and are boosted to the next energy level this “jump” is called a QUANTUM

13. Spectroscopy The study of substances exposed to a continuous source of “Exciting Energy” The study of substances exposed to a continuous source of “Exciting Energy” * Each element or compound produces a unique energy change when exposed to exciting energy unique Metals – burn certain colors Sodium – orangeBarium - green Lithium – redCopper - blue Potassium – lilacAluminum - silver

14. Fireworks Calculate the Energy Associated with each sparkler given the color Calculate the Energy Associated with each sparkler given the color NitrateColor Energy E = hc/λ Red (λ = 650 nm) Yellow (λ = 570 nm) Green(λ = 510 nm) Blue(λ = 475 nm) E = Energy, in units of Joules (kg·m 2 /s 2 ) h = Planck’s constant (6.626 x 10 -34 J·s) c = speed of light, 3.0 x 10 8 (m/s)