Presentation on theme: "3-Atomic Structure Overview Characteristics of Atoms"— Presentation transcript:
1 3-Atomic Structure Overview Characteristics of Atoms Interaction b/tw matter and lightPhotoelectric EffectAbsorption and Emission SpectraElectron behaviorQuantum numbers
2 Atomic Structure Atomic orbitals Periodic table Orbital energies Electron configuration and the periodic tablePeriodic tablePeriodic propertiesEnergy
3 Characteristics 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
4 Atomic StructureAtomic structure studied through atomic interaction with lightLight: electromagnetic radiationcarries energy through spacemoves at 3.00 x 108 m/s in vacuumwavelike characteristics
7 Wavelength () & Frequency () amplitude = number of complete cycles to pass given point in 1 second
8 Energy c = x = 3.00 x 108 m/s long wavelength low frequency Low EnergyHigh Energyshort wavelength high frequency
9 Energy Mathematical relationship: E = h E = energy h = Planck’s constant: 6.63 x 10–34 J s = frequency in s–1
10 Energy Mathematical relationship: E = h c = x E = Energy: directly proportional to frequencyinversely proportional to wavelength
11 Problems 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?
12 Photoelectric Effect Light on metal surface Electrons emitted Threshold frequency, oIf < o, no photoelectric effectIf > o, photoelectric effectAs , kinetic energy of electrons
13 Photoelectric 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
14 Problem 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.
15 Bohr Model Line spectra Light through a prism continuous spectrum: Ordinarywhitelight
16 Bohr Model Line spectra Light from gas-discharge tube through a prism line spectrum:H2 discharge tube
22 Electrons All electrons have same charge and mass Electrons have properties of waves and particles (De Broglie)
23 Heisenberg Uncertainty Principle Cannot simultaneously know the position and momentum of electronx = hRecognition that classical mechanics don’t work at atomic level.
24 Schrödinger Equation Erwin Schrödinger 1926 Wave functions with discrete energiesLess empirical, more theoreticaln Enn wave functions or orbitalsn2 probability density functions
25 Quantum Numbers Each orbital defined by 3 quantum numbers Quantum number: number that labels state of electron and specifies the value of a property
26 Quantum Numbers Principal quantum number, n (shell) Specifies energy of electron (analogous to Bohr’s n)Average distance from nucleusn = 1, 2, 3, 4…..
27 Quantum Numbers Azimuthal quantum number, (subshell) = 0, 1, 2… n–1 n = 2, = 0 or 1n = 3, = 0, 1, or 2Etc.1234spdfg
28 Quantum Numbers Magnetic quantum number, m Describes the orientation of orbital in spacem = –….+ If = 2, m = –2, –1, 0, +1, +2
29 Problem 3-5 Fill in the quantum numbers in the table below. n m 3 3s2–2, –1, 0, 1, 22p
30 Schrödinger Equation Wave equations: Each electron has & E associated w/ itProbability Density Functions: 2-graphical depiction of high probability of finding electron
31 Probability Density Functions Link to Ron Rinehart’s page energy2 probability density functions, p, d, f, g1s3s2sNode: area of 0 electron density
32 Probability Density Functions Node: area of 0 electron densitynodesLink to Ron Rinehart’s page
33 Electrons 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
34 Electrons and Orbitals = 0, m = 0, ms = ½2 electrons possible:1,0,0,+½ and 1,0,0,–½2 electrons per orbital1s1 H1s2 He
35 Electrons 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