Presentation on theme: "3-Atomic Structure Overview Characteristics of Atoms"— Presentation transcript:
13-Atomic Structure Overview Characteristics of Atoms Interaction b/tw matter and lightPhotoelectric EffectAbsorption and Emission SpectraElectron behaviorQuantum numbers
2Atomic Structure Atomic orbitals Periodic table Orbital energies Electron configuration and the periodic tablePeriodic tablePeriodic propertiesEnergy
3Characteristics of Atoms Atoms possess massAtoms contain positive nucleiAtoms contain electronsAtoms occupy volumeAtoms have various propertiesAtoms attract one anotherAtoms can combine with one another to form molecules
4Atomic StructureAtomic structure studied through atomic interaction with lightLight: electromagnetic radiationcarries energy through spacemoves at 3.00 x 108 m/s in vacuumwavelike characteristics
7Wavelength () & Frequency () amplitude = number of complete cycles to pass given point in 1 second
8Energy c = x = 3.00 x 108 m/s long wavelength low frequency Low EnergyHigh Energyshort wavelength high frequency
9Energy Mathematical relationship: E = h E = energy h = Planck’s constant: 6.63 x 10–34 J s = frequency in s–1
10Energy Mathematical relationship: E = h c = x E = Energy: directly proportional to frequencyinversely proportional to wavelength
11Problems 3-1, 2, & 3a) Calculate the wavelength of light with a frequency = 5.77 x 1014 s–1b) What is the energy of this light?2. Which is higher in energy, light of wave-length of 250 nm or light of 5.4 x 10–7 m?3. a) What is the frequency of light with an energy of 3.4 x 10–19 J?b) What is the wavelength of light with an energy of 1.4 x 10–20 J?
12Photoelectric Effect Light on metal surface Electrons emitted Threshold frequency, oIf < o, no photoelectric effectIf > o, photoelectric effectAs , kinetic energy of electrons
13Photoelectric Effect Einstein: energy frequency If < o electron doesn’t have enough energy to leave the atomIf > o electron does have enough energy to leave the atomEnergy is transferred from light to electron, extra is kinetic energy of electronEphoton = hphoton = ho + KEelectronKEelectron = hphoton – hoAnimation
14Problem 3-4A given metal has a photoelectric threshold frequency of o = 1.3 x 1014 s1. If light of = 455 nm is used to produce the photoelectric effect, determine the kinetic energy of the electrons that are produced.
15Bohr Model Line spectra Light through a prism continuous spectrum: Ordinarywhitelight
16Bohr Model Line spectra Light from gas-discharge tube through a prism line spectrum:H2 discharge tube
22Electrons All electrons have same charge and mass Electrons have properties of waves and particles (De Broglie)
23Heisenberg Uncertainty Principle Cannot simultaneously know the position and momentum of electronx = hRecognition that classical mechanics don’t work at atomic level.
24Schrödinger Equation Erwin Schrödinger 1926 Wave functions with discrete energiesLess empirical, more theoreticaln Enn wave functions or orbitalsn2 probability density functions
25Quantum Numbers Each orbital defined by 3 quantum numbers Quantum number: number that labels state of electron and specifies the value of a property
26Quantum Numbers Principal quantum number, n (shell) Specifies energy of electron (analogous to Bohr’s n)Average distance from nucleusn = 1, 2, 3, 4…..
27Quantum Numbers Azimuthal quantum number, (subshell) = 0, 1, 2… n–1 n = 2, = 0 or 1n = 3, = 0, 1, or 2Etc.1234spdfg
28Quantum Numbers Magnetic quantum number, m Describes the orientation of orbital in spacem = –….+ If = 2, m = –2, –1, 0, +1, +2
29Problem 3-5 Fill in the quantum numbers in the table below. n m 3 3s2–2, –1, 0, 1, 22p
30Schrödinger Equation Wave equations: Each electron has & E associated w/ itProbability Density Functions: 2-graphical depiction of high probability of finding electron
31Probability Density Functions Link to Ron Rinehart’s page energy2 probability density functions, p, d, f, g1s3s2sNode: area of 0 electron density
32Probability Density Functions Node: area of 0 electron densitynodesLink to Ron Rinehart’s page
33Electrons and Orbitals Pauli Exclusion Principle: no two electrons in the same atom may have the same quantum numbersElectron spin quantum number ms = ½Electrons are spin paired within a given orbital
34Electrons and Orbitals = 0, m = 0, ms = ½2 electrons possible:1,0,0,+½ and 1,0,0,–½2 electrons per orbital1s1 H1s2 He
35Electrons and Orbitals = 0, m = 0, ms = ½2,0,0, ½2 electrons possible = 1, m = –1,0,+1, ms = ½2,1,–1, ½ ,1,0, ½ 2,1,+1, ½6 electrons possible