Ch 5-1 Properties Of Light
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CH 5 ELECTRONS IN ATOMS 5-1 Light and Quantized Energy Some elements emit visible light when heated with a flame. This chemical behavior is due to the
arrangement of e- in atoms.
ELECTROMAGNETIC RADIATION Form of energy that exhibits wave-like behavior as it travels through space. There are many types of electromagnetic radiation and all are represented in the ELECTROMAGNETIC SPECTRUM
ELECTROMAGNETIC SPECTRUM
PARTS OF A WAVE
Frequency (v, nu) –The number of complete wavelengths that pass a given point each second. Units: wave/second = 1/s = s-1 = Hertz (Hz)
Wavelength (λ , lambda) – The distance between identical points on successive waves. (crest to crest or trough to trough) Units: meters (m)
c=λ v c = speed of light, 3.00 x 108 m/s
WAVE NATURE OF LIGHT
Max Planck theorized that all matter can gain/ lose energy in small “chunks” of light (quanta).
Quantum- minimum amt of energy that can be gained or lost by an atom. o o
Ex: Iron when hot appears red or blue, emits nrg that is quantized has a specific frequency. Heating water – temp increases by molecules absorbing a specific amt or quanta.
Calculated as follows: Equantum = hv o o o
E = Energy (J) h = Planck’s constant 6.626 x 10-34 (J s) v = frequency ( Hz or s-1 )
PARTICLE NATURE OF LIGHT Photoelectric effect – electrons are emitted from a metal’s surface when light of a specific frequency shines on the surface. Albert Einstein (1905) assumed that light travelled as a stream of tiny particles or packets of energy called photons. Photons- EM radiation w/ no mass that carries a quantum of energy.
EM radiation has both wavelike and particle- like nature. Ephoton = hv
Photon = quantum of energy
ATOMIC EMISSION SPECTRA Set of frequencies of light waves emitted by an atom of an element. Line spectrum – consists of several individual lines of color from light energy emitted by excited unstable atoms
Only certain colors (frequencies) appear in an element’s AES & it can be used to identify the element.
arrangement of e- in atoms.
ELECTROMAGNETIC RADIATION Form of energy that exhibits wave-like behavior as it travels through space. There are many types of electromagnetic radiation and all are represented in the ELECTROMAGNETIC SPECTRUM
ELECTROMAGNETIC SPECTRUM
PARTS OF A WAVE
Frequency (v, nu) –The number of complete wavelengths that pass a given point each second. Units: wave/second = 1/s = s-1 = Hertz (Hz)
Wavelength (λ , lambda) – The distance between identical points on successive waves. (crest to crest or trough to trough) Units: meters (m)
c=λ v c = speed of light, 3.00 x 108 m/s
WAVE NATURE OF LIGHT
Max Planck theorized that all matter can gain/ lose energy in small “chunks” of light (quanta).
Quantum- minimum amt of energy that can be gained or lost by an atom. o o
Ex: Iron when hot appears red or blue, emits nrg that is quantized has a specific frequency. Heating water – temp increases by molecules absorbing a specific amt or quanta.
Calculated as follows: Equantum = hv o o o
E = Energy (J) h = Planck’s constant 6.626 x 10-34 (J s) v = frequency ( Hz or s-1 )
PARTICLE NATURE OF LIGHT Photoelectric effect – electrons are emitted from a metal’s surface when light of a specific frequency shines on the surface. Albert Einstein (1905) assumed that light travelled as a stream of tiny particles or packets of energy called photons. Photons- EM radiation w/ no mass that carries a quantum of energy.
EM radiation has both wavelike and particle- like nature. Ephoton = hv
Photon = quantum of energy
ATOMIC EMISSION SPECTRA Set of frequencies of light waves emitted by an atom of an element. Line spectrum – consists of several individual lines of color from light energy emitted by excited unstable atoms
Only certain colors (frequencies) appear in an element’s AES & it can be used to identify the element.
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