Unformatted text preview: PreAP Notes chpt 5 Electron Configuration I. Electromagnetic Spectrum and Theory of Electron Shapes (chapter 5 pgs 116 133) A. Energy that has wave like behavior B. Terms to learn 1 1. Wavelength = λ (lambda) = measure from crest to crest or trough to
nm ( 1 x 10 9 meters nm ( 1 x 10 a) Measured in m, cm, or Measured in Hertz = 1/s or s-1 2. Frequency = ν(nu) = number of waves going through a given point 1. Amplitude = wave height Read How a Laser works page 144 on the online text now C. Waves travel at speed of Light ****C = λν ****C λν Work practice problems number 1,2,3 bottom of page 121 1. Speed of light = 3.00 x 10 8 m/sec in a vacuum Speed PreAP Notes chpt 5 Electron Configuration 2 D. Classification of Electromagnetic Radiation 1. Waves have the same speed a) Waves can have different wavelengths and frequencies b) Looking at the EM Spectrum= relationship between wavelength and frequency in an inverse relationship wavelength 2. Particle Nature of Light a) Max Planck = matter can gain or lose energy only in small quanta or in specific amounts Equantum= h v h = Planck’s constant = 6.626 x 10 -34J ∙ s 3. Photoelectric Effect a) Electrons are emitted from a metal’s surface when light with a certain frequency shines on the surface of certain substances certain b) Look at picture on top of page 123 of your textbook 4. Einstein • • Proved that light has wave and particle characteristics Light is a wave with bundles of energy called photons a) Energy of a Photon
photon • E = h ∙í • The energy of a photon must have a certain minimum threshold value to eject
electrons from metals Do A Practice Problem • Problem number 5 bottom page 124 Look at Figure 7.6 See the difference between a continuous spectrum (a) and a hydrogen line spectrum (b) E. Atomic Emission Spectra 1. Definition = Atomic emission spectrum of an element is equal to a set of frequencies of the EM Spectrum emitted by atoms of an element of Look at page 126 of your book PreAP Notes chpt 5 Electron Configuration The spectrum is not continuous Why not ?????? 2. Bohr Model of the Atom − Studied hydrogen − The H electron has only certain allowable energy states 3 – Lowest energy state = ground state – When it absorbs energy, then excited = Look at page 127 of your book
a) Shortcoming of Bohr Model r Explained only H W r Did not explain chemical behavior of the elements W 3. Louis de Broglie r 1924 – If waves can have particle like behavior than can particles of W matter have wave like properties matter Yes!!!! All moving bodies have a wavelength ë=h mv ë = wavelength of a particle m = mass h = planck V = velocity velocity 4. Heisenberg Uncertainty Principle 4. a) Impossible to tell the velocity and position of a particle at the same time same 5. Schrodinger r Treated the electron of the hydrogen atom as a wave W r Makes no attempt to describe a path but just a probable region of electron W location location r Boundaries of orbitals are fuzzy W Boundaries r ******To overcome uncertainty, an orbital surface is defined to W contain 90% of an electron’s probable distribution***** contain Representations of the Hydrogen 1s, 2s, and 3s Orbitals Representations Shape ?___________________________ The Boundary Surface Representations of All Three 2p Orbital PreAP Notes chpt 5 Electron Configuration Shape ?________________________________ The Boundary Surfaces of All of the 3d Orbitals Shape number ___________________________________ Representation of the 4f Orbitals in Terms of Their Boundary Surfaces Shape Number_______________________________________ F. Electron configuration = ways electrons are arranged around an atom 1. Electron clouds only give you a probability of electron existences. We use quantum numbers to describe quantum A. Principle Quantum number = N = indicates most probable distance of the electron from the nucleus a) b) B. Orbital Quantum number = l = indicates the shape of the 4 orbitals a) b) Level 1 Level 2 Level 3 Level 4 Level 5 C. Magnetic Quantum number = m = the number of positions of C. clouds around 3 axis in space of the orbit a) b) D. Spin Quantum Number = s = tells whether an electron is spinning clockwise or counterclockwise
a) b) Developed by Pauli. Called Pauli Exclusion Principle DO WORKSHEET ON QUANTUM NUMBERS PreAP Notes chpt 5 Electron Configuration 5 PreAP Notes chpt 5 Electron Configuration 6 2. Methods of drawing the electrons of the atom 2. Methods of drawing the electrons of the atom A. Electron configuration notation= use a chart with the DIAGONAL RULE Now just use the periodic chart and the noble gasses ( easy, easy!) PreAP Notes chpt 5 Electron Configuration 7 B. Orbital Notation = this method breaks down each subshell into individual orbits 1) Aufbau principle = electrons enter orbitals of lower energy first 2) Pauli Exclusion = electrons must have opposite spins. Can have only 2 electrons per cloud shape 3) ***Hund’s Rule*** = when orbitals of identical energy are available, electrons tend to occur in these singly rather than in pairs. We use arrows a Ex = the p suborbital has a capacity of 6 electrons and has 3 cloud shapes ____ ____ ____ b. If you had 2 electrons in the p suborbital, the arrows are drawn as _____ _____ _____ c Example of a d orbital notation with 6 electrons ___ ____ ____ ___ ____ Do a worksheet for practice C. Electron Dot Configuration 1) This is least used for details of electron locations because it only represents the outer electron shell electrons or valence electrons 2) The outer most electrons are known as valence electron. These are the electrons that can be shared or given to another atom 3) Examples PreAP Notes chpt 5 Electron Configuration 8 3. Exceptions to predicted configurations A. The Aufbau works all the way up until number 23 V but chromium and copper show a difference from what is expected 1) Why – half filled orbits and filled sets of s and d orbitals or more stable more 2) Do the electron configurations of copper Expected In reality 3) Do the electron configurations for chromium Expected In reality B. Sometimes electrons jump or hybridize to different suborbitals on the same level so that more bonds can be formed with other elements Ex. Carbon Silicon ...
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- Spring '08