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

  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-s: spherical, lowest energy

Principle-p: dumbbell

Diffuse-d: 4 lobes

Fundamental(flower)-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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