4 Electron Configurations Electron configurations are...
5 Electron Configuration Vocab Principle Energy Levelcorrelates to the period (1-7), periods go from left to right across the periodic tableSublevelare located in the principle energy level. There are 4 that we will talk about s, p, d and f.Orbitallocated in the sublevel. Where electrons are most likely to be found1 ORBITAL HOLDS 2 ELECTRONS
6 Writing Electron Configurations Principle Energy Level[sublevel]number of electrons ORa[b]cGet your periodic table!Start from left to right!
7 Orbital Diagrams Tool for creating electron configurations 2 dimensional representation of where electrons are in an atom
8 Aufbau Principleelectrons are added to the lowest available energy level.Hydrogen as an example:
9 Pauli Exclusion Principle each orbital can hold two electronsthose electrons must have opposite spinsspin is represented by the arrow facing up or down.
10 Hund’s RuleOrbitals of equal energy are occupied by one electron before 2 electrons occupy 1 orbital. The second electron is added after all orbitals have one electron
12 Noble Gas Configuration – Short cut Locate the element on the PTTrace backward to the nearest noble gasPut that noble gas in  (brackets)Fill in remaining electrons
13 Principle Quantum Numbers Quantum numbers define the characteristics of a particular electron.Work as an address for the electronelectrons repel each other, no two electrons can have the same address.Pauli Exclusion principle
14 Quantum Numbers – electron Address StateCityStreetNumber ofyour homen - principle energy level1, 2, 3,l – sublevel“shape” of the region of space (s, p, d, f)m - orbital orientationaxes of the magnetic moment.s – spinCan be +1/2 or –1/2 for electrons
15 Valence Electrons Electrons in the HIGHEST energy level (n) Electrons that interact during chem rxnsAlways in the s & p sublevels
16 Finding Valence Electrons Locate the highest energy levelCount the electrons presentOrbital diagrams SUPER helpfulExample: SulfurHow many valence e’s?
22 Heisenberg Uncertainty Principle An electron’s location and speed cannot be determined at the same time.If we cause change to find one variable, we are no longer looking at the actual e- situation.If we need to slow or stop it to locate it or if we need to locate it to find its speed, then we allow the chance of change.So quantum mechanics can tell us the probability that an electron is somewhere, but it does not tell us how it got there.
23 Nodal SurfacesA nodal surface is a region that defines the border of an orbital. This is where the probability function equals zero. Electrons CAN NOT exist in this area.Nodal surfaces are NOT spherical for other orbitals.Nodal surfaces are spherical for the “s” orbitals.2p orbital3s orbital
27 Wave Comparison Red Light Low frequency Long wavelength Violet Light nm = 1 x 10-9 mRed LightLow frequencyLong wavelengthViolet LightHigh frequencyShort wavelength
28 Waves & WavelengthHow many wavelengths are represented in each figure below?
29 C=It stands to reason that if energy is constant then (wavelength) is inversely proportional to (frequency).ORAs wavelength increases frequency decreases
30 Max PlanckMax Planck mathematically determined “h” that could be multiplied by to solve for energy (E) every time an electron gave off light as it fell. (This simply means that all wavelengths are proportional)E = hThus E will tell us the relative distance apart of each energy level in a given atom based upon the spectral lines.
31 C=Remember that Einstein told us that matter and energy are the same thing. Matter is simply frozen energy.From Einstein we were able to come up with several more equations to understand quantum mechanics.C= = wavelengthEx: yellow orange = 580 nanometersSo as in the lab, using a spectroscope we can determine the wavelength of the color of light (). We can solve for frequency () mathematically.
32 De BroglieDe Broglie argued that as particles (i.e.electrons) drop back to lower energies, photons of energy are given off in “packets” or specific amounts called quanta. His doctoral board scoffed and was ready to deny his degree but changed their minds when Einstein supported him fully.His model changed the Bohr model so that all elements could be explained according to their frequencies of energy.Remember that energy is constant and that standing waves are quantized as well (they only increase by multiples of ½)
33 De BroglieEssentially the model went fromde BroglieBohrto
34 SpectraWith the de Broglie Model, it became possible to explain the spectral lines of all models.Each wavelength would allow electrons to fall back to lower energy levels emitting various energieswhich translate to frequencies thus defining a wavelength
36 Some Atomic Emission Spectra HydrogenMercuryArgonHelium
37 de Broglie and Wave Model An electron in its path is associated with a wavelength.The wavelength depends on the mass:
38 Example ProblemWhat is the characteristic wavelength of an electron with a velocity of 5.97 x 106 m/s? (Use 9.11 x kg for the mass of an e-)
39 Bright-line SpectraAtoms are quantized, existing only in definite energy states so an atom absorbs a specific quanta of energy pushing electrons to higher energy levels. An “EXCITED” electron jumps from its ground state to a higher energy level. The energy cannot be maintained so it falls back to where it came from losing exactly the same amount of energy that it absorbed.
40 Energy of ElectronsWe can calculate the energy the electrons of a hydrogen atom emit when they fall by using the Balmer equationSo if an electron falls from the 6th energy level to the 2nd energy level then –Note: energy levels are not actually distances between electrons and the nucleus.n = 3,4,k = constant = 2.179x10-18
42 Quantum or Wave Mechanics Schrodinger applied idea of e- behaving as a wave to the problem of electrons in atoms.He developed the WAVE EQUATIONSolution gives set of math expressions called WAVE FUNCTIONS, Each describes an allowed energy state of an e-E. Schrodinger
43 Waves: standing, travelling Q1 - A standing wave is the combination of two waves (travelling in opposite directions). It has nodes, where a portion of the wave remains stationary (spring demonstration)W = 0.5W = 1.5W = 1W = 2Notice that a standing wave (which is what an electron is) can only have certain wavelengths (0.5, 1, etc.) because the ends are fixed as nodes