2 Wave Nature of LightElectromagnetic radiation which is a form of energy that exhibits wavelike behavior as it travels through space.Examples: light, radio waves, x-rays, etc
3 Parts of a Wave crest wavelength amplitude origin amplitude wavelength trough
4 Wavelength Waves have a repetitive nature. Wavelength- ( lambda) shortest distance between corresponding points on adjacent waves.Measured in units like meters, centimeters, or nanometers depending on the size.1 x 10-9 meters = 1 nanometer
5 c = lf Frequency # of waves that pass a given point per second. Units are waves/sec, cycles/sec or Hertz (Hz)Abbreviated n the Greek letter nu or by an fc = lf
6 Frequency and wavelength Are inversely relatedAs one goes up the other goes down.High frequency, Short WavelengthLow frequency, Long Wavelength
7 Speed of light = (wavelength) x (frequency) Wave FormulaAll electromagnetic waves, including visible light, travel at the speed of 3.00 x 10 8 m/s in a vacuum.Speed of light = c = 3.00 x 108 m/sc=fSpeed of light = (wavelength) x (frequency)
8 Example ProblemWhat is the wavelength of a microwave having a frequency of 3.44 x 109 Hz?Formula: c=f= ?f = 3.44 x 109 Hzc = 3.00 x 108 m/s3.00 x 108 m/s = (3.44 x 109 s-1)3.00E8 / 3.44E9 = 8.72 x 10-2 m
9 PracticeWhat is the frequency of green light, which has a wavelength of 5.90 x 10-7m?A popular radio station broadcast with a frequency of 94.7MHz, what is the wavelength of the broadcast? ( frequency needs to be is Hz)
10 Different frequencies produce different types of waves. The entire range of frequencies is called the electromagnetic spectrumWe are only able to see with our eyes a small portion of the spectrum = visible lightROY G BIVDifferent colors mean different frequencies/wavelengths
11 Energy & The SpectrumThe energy of a wave increases with increasing frequencyHigh Frequency = High EnergyLow Frequency = Low EnergyBlue light has more energy than Red light
13 Quanta Max Planck suggested the idea of quanta or packets of energy. Quanta is the minimum amount of energy that can be lost or gained by an atom.Energy is quantized = it comes in packets (like stairs or pennies only whole numbers)
14 Energy = (Planck’s constant)(frequency) h = x J.s (Joule seconds)Energy = (Planck’s constant)(frequency)E = h fExample: What is the energy in Joules of a photon from the violet portion of the rainbow if it has a frequency of 7.23 x 1014 Hz?E = ?h = x Jsf = 7.23 x 1014 Hz (or s-1)E = (6.626 x Js)(7.23 x 1014 s-1)E = 4.79 x J
15 Photoelectric EffectIn the 1900s, scientist studied interactions of light and matter.One experiment involved the photoelectric effect, which refers to the emission of electrons from a metal when light shines on the metal.This involved the frequency of the light. It was found that light was a form of energy that could knock an electron loose from a metal.
16 Photon Light waves can also be thought of as streams of particle. Einstein called these particles photons (He won a Nobel Prize for this)A photon is a particle of electromagnetic radiation having zero mass and carrying a quantum energy.
17 Bohr’s Model Why don’t electrons fall into nucleus? Bohr suggested that they move like planets around sun.Certain amounts of energy separate one level from another.
18 Nucleus is found inside a blurry “electron cloud”
20 } Bohr’s Model Further away from nucleus means more energy. Fifth There is no “in between” energyEnergy LevelsFifthFourthThirdIncreasing energySecondFirstNucleus
21 Bohr Model of the AtomGround state- the lowest energy state of an atom.Excited state – state in which an atom has a higher potential energy than its ground state.Energy is quantized. It comes in chunks.quanta - amount of energy needed to move from one energy level to another.Since energy of an atom is never “in between” there must be a quantum leap in energy.
22 Bohr Energy Levels K = 2 electrons – 1st L = 8 electrons – 2nd M = 18 electrons – 3rdN = 32 electrons – 4th
23 Heisenberg Uncertainty Principle This is the theory that states that it is impossible to determine simultaneously both the position and velocity of an electron or any other particle.
24 Quantum TheorySchrodinger derived an equation that described energy & position of electrons in atomSchrodinger along with other scientists laid the foundation for the modern quantum theory, which describes mathematically the wave properties of electrons and other very small particles.