4 Where are the electrons? Electrons are traveling at 6 x 10⁶m/sec around the nucleusPerspective of the speed:How long would it take a space vehicle to travel to the moon at the electron’s speed?
5 Distance fromEarth to Moon:383,401 kmFastest travel to the moon8 hours, 35 minutesPluto mission fly-by
6 Electrons: Earth to moon distance: 383,401 km Convert to meters Calculate the time to travel to the moon at the speed of an electron (6 x 10⁶ m/sec):Distance = Time x Speed
7 Electrons & Electromagnetic Radiation By studying the light emitted when heating up a chemical sample, scientists better understood the electron:Its position in the atom;Its energy; &Its role (bonding = forming compounds)Scientists used the electromagnetic radiation to study electrons
8 Electromagnetic Radiation Form of energy that has a wave-like propertiesCharacterized byWavelengthFrequencyEnergy
17 Bohr’s discovery and model: saved video from Discovery Education Starts with historical perspective
18 Bohr’s Model of the Atom Electrons orbit the nucleus at:At the lowest energy level possibleCalled the ground stateElectrons can be excited by:Electricity, light, chemical reactionsWhen excited, an electron will absorb only a certain amount of energy,A “packet” of energy called a photon or quantum
19 Bohr’s model When excited, the electron Will jump to a higher energy levelCalled the excited stateThe electron does not stay in the excited state but falls back toward the nucleus and releases energy
25 How do neon lights produce the glowing colors? FACTS:Neon is a colorless, inert (non-reactive, non-flammable) gasNeon lights are tubes filled with neon gas.
26 Neon atoms Normal conditions Electricity passing through the tube Electrons are at the ground stateNo light (energy) is emittedElectricity passing through the tubeAtoms absorb energyElectrons become excited and unstableElectrons are pulled back toward the nucleusElectromagnetic radiation is emitted
27 Elements and their electromagnetic radiation Emissions spectrumUnique for each elementElectrons are excited by electricityWhen they are pulled back by the ____________, they give off __________
28 Emission Spectrum White light Hydrogen: Nitrogen: Mercury: Neon: Write the order of the colorsHydrogen:Nitrogen:Mercury:Neon:Other:
31 Emissions Spectra - Simulation Produce light by bombarding atoms with electrons. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors.
32 Emission Spectra Unique for each element Used to identify elements as part of unknown compounds
37 Electrons in models of atoms Exploratory LabHow did scientists figure out the structure of atoms without looking at them? Try out different models by shooting light at the atom. Check how the prediction of the model matches the experimental results.
38 Quantum Model Video – www.teachersdomain.org (thinking behind current atomic model)The space in between
39 Video electron arrangement Video – (low volume)
40 Probable location of the electron The electron arrangement represents where an electron can be found 90% of the time.
54 Energy Diagram n = principal energy level Sublevels: Orbitals Electrons & spinIncreasing EnergyExamples: Sulfur & IronNucleus
55 Energy Diagram Students: Phosphorus Calcium Krypton n = principal energy levelSublevels:OrbitalsElectrons & spinIncreasing EnergyStudents:PhosphorusCalciumKryptonNucleus
56 Energy Diagram n = principal energy level Sublevels: Orbitals Electrons & spinIncreasing EnergyNucleus
57 Energy Diagram n = principal energy level Sublevels: Orbitals Electrons & spinIncreasing EnergyNucleus
58 Orbital NotationThe orbital is indicated by a line____ wioth the name written below.Arrows represent the electrons.ExamplesNe: ___ ___ ___ ___ ___1s 2s 2p 2p 2p___ ___ ___ ___ ___ ___ ___ ___ ___ ___Note: You must write both the lines and the orbital designations under the lines
59 Electron Configuration ElementAtomic #Orbital diagramElectron ConfigurationHHeLiBeBCNOFNeNa
60 Practice Orbital Notation ___ Element Atomic # Z 1s H He ___ ___ Li ___ ___1s s1s 2s___ ___ ___ ___ ___1s 2s 2p 2p 2pElement Atomic # ZHHeLiBeB
62 Electron Configuration Principal energy level + sublevelUse superscripts to show number of electrons in each sublevel1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
63 Electron Configuration: Sublevel diagram Determining order: Aufbau rulesn=1n=2n=3n=4n=5see figure 5-19 on p.138Know how tomake this chart!
64 Electron Configuration ElementAtomic #Orbital diagramElectron ConfigurationHHeLiBeBCNOFNeNa
65 Check your electron configuration answers using the Periodic Table S, P, D, FBlocksPeriods18
66 Valence ElectronsElectrons in the outermost (highest) principal energy levelImportantParticipate in bonds to make compounds1s² 2s² 2p⁶ 3s² 3p⁶ 4s²1s² 2s² 2p⁶ 3s² 3p⁴1s² 2s² 2p⁶ 3s¹1s² 2s²1s¹
67 Electron Configuration WritePotassiumAluminumChlorineCircle the valence electrons.
68 K Al Cl Electron Dot Notation Represents valence electrons Maximum number = 8Octet rule: atoms will lose, gain or share electrons to have 8 valence electrons & become stable
69 Introducing Noble Gas Notation Analyze the following examples and propose the rules for writing Noble Gas Notation.chlorine [Ne] 3s²3p⁵iron [Ar] 4s²3d⁶zinc [Ar] 4s²3d¹⁰barium [Xe] 6s²
70 Noble Gas Notation Short cut method for electron arrangement Use the noble gas in the period above the elementExample:Na 1s² 2s² 2p⁶ 3s¹Use NeonRepresent neon’s configuration 1s² 2s² 2p⁶as [Ne]- Use in Na: [Ne] 3s¹
80 Electron Configuration Aufbau is the Rule.Note: However, sometimes the electron configurations are written in energy level sequence rather than Aufbau sequence.This is mostly used for the “d” sublevel.Aufbau sequenceTi: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d²Energy level sequenceTi: 1s² 2s² 2p⁶ 3s² 3p⁶ 3d² 4s²