Teacher Notes


Teacher Notes
Publication No. 13951
Electron Structure—1s OrbitalStudent Laboratory KitMaterials Included In Kit
Dice, 15 pairs
Energy Level Worksheets, 15 Safety PrecautionsThis laboratory is considered nonhazardous. Follow all normal laboratory safety procedures. Lab Hints
Teacher Tips
Correlation to Next Generation Science Standards (NGSS)^{†}Science & Engineering PracticesDeveloping and using modelsAnalyzing and interpreting data Using mathematics and computational thinking Disciplinary Core IdeasMSPS1.A: Structure and Properties of MatterHSPS1.A: Structure and Properties of Matter Crosscutting ConceptsSystems and system modelsPatterns Answers to Prelab Questions
Sample Data{13951_Data_Table_1}
Energy Level Worksheet
{13951_Answers_Figure_4}
Referring back to your original data, place a circle in the Energy Level Worksheet for your first 32 rolls of the dice. For example: If roll 1 gave a 9, then place a circle (•) in the 9 box for roll 1. Answers to QuestionsPlot the numbers obtained for each roll of the dice as a histogram for energy level 1 (1s orbital). The xaxis represents the number rolled and the yaxis represents the frequency each number was rolled. Put an X in the box corresponding to the dice roll. If the dice roll value has been previously entered, place the X in the box above the last X entry. Note: The shaded area represents the Bohr radius for the electron in the lowest energy level. {13951_Answers_Figure_3}
ReferencesSpecial thanks to Gary Schiltz, Glenbard West High School, Glen Ellyn, IL, for providing the idea and the instructions for this activity to Flinn Scientific. 
Student Pages


Student PagesElectron Structure—1s OrbitalIntroductionModel the difficult concept of wave mechanics by actually “rolling the dice” to determine where the electron may be located. Concepts
BackgroundThe investigation and development of an accurate Atomic Model has been ongoing for many years. John Dalton (1766–1844) gave us the first model based on experimental evidence—atoms are the smallest discrete parts of a substance that cannot be divided. He also determined that elements differ due to the mass of their atoms. When new data became available, the Atomic Model was modified to fit the new evidence. {13951_Background_Figure_1}
If data are collected from the “Bohr Atomic Camera,” then a graph or histogram can be created. Figure 2 shows a histogram plotting the distance the electron is from the nucleus for each snapshot.
{13951_Background_Figure_2_Position of electron—Bohr model}
Bohr based the theory of electron structure on experimental evidence showing that atoms, when energetically excited, generate well defined spectral lines. Bohr proposed that these spectral lines resulted from the release of energy when an electron that has been excited through the absorption of energy “falls” back down to a lower or more stable quantized energy level or its ground state. For a model to be useful, it must allow for accurate predictions. Bohr’s model correctly described the electron energy levels for the hydrogen atom, which has only one electron, but failed to explain the data for atoms containing two or more electrons. To explain the observed data for multielectron atoms, Bohr’s atomic model needed to be modified. New experiments suggested that matter, like light, has both wavelike and particlelike characteristics. From this wavelike nature of matter, Werner Heisenberg (1901–1976) concluded that knowing both the position and energy of an electron at the same time would be impossible. If the energy of an electron is known, then the position of the electron can only be estimated. Likewise, if the precise location of the electron is known, then its energy can only be estimated. The probability of finding an electron with a given energy within a given space is calculated using a complex mathematical equation called a wave function, Ψ. When this wave function is squared, the result is the probability of finding an electron with a specific energy in a given region of space. The electron orbital can be thought of as the region of space where the probability of finding an electron with a given energy is greater than zero. At large distances from the nucleus, the probability of finding the electron is very small, but never reaches zero. Scientists therefore defined the relative 1s orbital size as the radius of a sphere where 90% of the time the electron is in that sphere. The modified wave–mechanical model still treats the electron as a particle, but adds a new property. This new property is that the electron movement is best described as a standing wave pattern around the nucleus. How will the wave nature of the electron affect the position of the electron if we were to again take snapshots of the electron now exhibiting this wave property around the nucleus? Experiment OverviewThe purpose of this experiment is to simulate the probability of finding an electron by “rolling the dice.” Each roll of the dice will represent the electron location results for the wave mechanical probability calculations. The total value of the dice generated for each of fifty rolls of the dice will be recorded and the results will be plotted to create a histogram. The histogram will show the frequency of occurance for each value, that is, it will model the probability of finding the 1s electron at a particular location from the nucleus. Materials
Dice, pair
Energy Level Worksheet Prelab Questions
Safety PrecautionsThis laboratory is considered nonhazardous. Follow all normal laboratory safety procedures. ProcedureEach roll of the dice represents taking a snapshot of the distance of the electron from the nucleus for the lowest energy level (1s orbital) at that instant.
Student Worksheet PDF 