5 Electromagnetic Spectrum All forms move at speed of light, c, 3.00x108 m/sForms identified by:wavelength, , the distance b/ corresponding points on adjacent waves. Units: nm, cm, or mFrequency, , # of waves that pass a given point in a specific time, 1 sec. Unit: 1/s = Hertz, Hz
7 Wavelength and Frequency Inverse proportion equation!!Frequency, 1/sspeed of light, m/swavelength, m
8 CalculationCalculate the wavelength of a radio wave with a frequency of x 106s-1Determine the frequency of light whose wavelength is nm.
9 Particle Nature of Light Photoelectric Effect: emission of electrons from a metal when light shines on the metal
10 Photoelectric EffectLight had to be certain frequency to knock e- looseWave theory any frequency should work (just might take a while)Light must also be a particle!Max Planck(1900) explanation: objects emit energy in small packets called quantaVideo - 16
11 Max PlanckQuantum of energy is the smallest amount of energy that can be lost or gained by an atomE = hFrequency, s-1Energy of quantum, in joules, JPlanck’s constant, 6.626x10-34 Js
12 Energy CalculationWhat is the energy of green light, with a wavelength of 500. nm?
13 Albert Einstein Light is both wave and particle! Particle of light = photon, having zero mass and a quantum of energyPhotons hit metal and knock e- out, but photon has to have enough energy
14 H-atom Emission Spectrum Pass a current through gas at low pressure it excites the atomsGround state: lowest energy state of an atomExcited state: atom has higher potential energy than it has in ground state
15 H – Atom SpectrumWhen atom jumps from excited state to ground state it gives off energy LIGHT!E2Ephoton = E2 – E1 = hvE1
22 Bohr Model of H-atomFrom wavelengths of emission spectrum Bohr calculated energy levels of H-atomModel worked ONLY for H-atom
23 Quantum Model of Atom Can e- behave as a wave? Yes!To find e- use a photon, but photon will knock the e- off courseHeisenberg Uncertainty Principle: impossible to determine position and velocity of a particle at the same time.
24 Schrödinger Wave Equation 1926 – developed equation and only e- waves of certain frequencies were solutionsQuantization of e- probability of finding e- in atomNo neat orbits probability clouds or orbitals
26 Atomic OrbitalsDef: 3-D region around nucleus that indicates the probable location of an electronEnergy levels or shells:Numbered 1-7Smaller number = closer to nucleus, lower energy
27 Sublevels Each shell has sublevels s p d f 1 – s orbital 3 – p orbitalsd5 – d orbitalsf7 – f orbitals
28 Shells and Sublevels Shells and sublevels together: 1s 2s, 2p 3s, 3p, 3d4s, 4p, 4d, 4f, etc.s is the lowest energy and f is the highest
29 Orbitals Each orbital in a sublevel can hold a maximum of 2 e- 1 – s 2 e- max.3 – p orbitals 6 e- max.5 – d orbitals 10 e- max.7 – f orbitals 14 e- max.
30 Electron Configurations Arrangement of e- in atomOrbital Notation:H has 1e-Rules:Aufbau Principle: electron occupies lowest energy level that can receive it
31 Electron Configurations 2. Pauli Exclusion Principle: no two e- in an sublevel orbital can have the same spin3. Hund’s Rule: orbitals of equal energy are occupied by one e- before pairing up e-. All single occupied orbitals must have same spin.He – 2e-