Wave-Particle Nature of Light
-Rutherford’s time
-Electrons: Particles
-Light: Waves
-1900’s: 1. Electrons have certain wavelike properties
2. Light has certain particle like properties
-Duel wave-particle nature
Wave Behavior
Electromagnetic Radiation: Form of energy that exhibits wavelike behavior as it travels
through space
-Moves through a vacuum at 3.0 x 108 m/s
-Speed of light in air
Electromagnetic Spectrum: Consists of all electromagnetic radiation, arranged according to
increasing wavelength
Wavelength ( lambda): The distance between corresponding points on adjacent waves
Frequency (
nu): The number of waves that pass a given point in a specific amount of time
(usually 1 s)
-As wavelength decreases: Frequency increases
-As wavelength increases: Frequency decreases
-Frequency measured in Hz
1 Hz = 1 wave/s
Continuous Spectrum: A spectrum in which all wavelengths within a given range are included
(rainbow of colors)
Particle Behavior
Photoelectric effect: Emission of electrons by certain metals when light shines on them
-Max Plank: Proposed that hot objects lose energy
-Not loosing it continuously
-Packets of energy (Quanta)
-Quantum: A finite quantity of energy that can be gained or lost by an atom
-Photon: A quantum of light
E = hv
E: Energy of photon
H: Planks constant = 6.626 x 10-34 J.s
V: frequency
Light can be described as particles or waves
Quantum Model of Atom (electron cloud)
-1924 Louis de Broglie (French physisist)
-Proposed that electrons may also have wave-particle nature
-Electrons can be thought of as waves confined to space around the nucleus
II. Quantum Numbers: Specify the properties of atomic orbitals and their electrons
-Derived from the Schrodinger equation
-Indicates region occupied by a given orbital in terms of
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1. Distance from nucleus
2. Orbital shape
3. Orbital position in respect to the 3 dimensional x,y,z axis
4. Specifies one or two possible orientations
1. Principle Quantum Number: (n) indicates the main energy levels surrounding the nucleus
-Shells (equivalent to Bohr orbits)
n = 1-7 in their ground states
Orbital quantum Numbers: Indicates the shape of an orbital
Sharp
Principle
Diffuse
Fundamental (flower)
-s: spherical, lowest energy
-p: dumbbell
-d: 4 lobes
-f: Complex: highest energy
3. Magnetic quantum numbers: Indicates the orientation of an orbital around a nucleus
4. Spin quantum number: 2 possible values (+1/2, -1/2) indicates two possible states of e- in an
orbital
-Spin on axis generating a magnetic field
a. Magnetism: All magnetic phenomena stem from motions of electrons about the nuclei of
atoms
4.3 Electron Configuration: Arrangement of electrons in atoms
1. Aufbau principle (building up): An electron occupies the lowest-energy orbital that
can receive it
2. Hund’s Rule: Orbitals of equal energy are each occupied by one electron before any is
occupied by a second electron
3. Pauli Exclusion Principle: No two electrons in the same atom can have the same 4
quantum numbers
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