The Boarding House Model: A Guide to Electron Configurations

Electron Configurations What is the electron structure in an atom? Why? The electron structure of an atom is very important. Knowing it can help scientists predict bonding in molecules, the charge(s) an atom might have and the physical properties of the element. In order for scientists to study the electron structure in an atom, they give the electrons “addresses”. Just like your address might include a house number, street, city and state, an electron’s “address” has multiple parts. In this activity, you will learn how the electrons fill up the available spaces in an atom and how their “addresses” or configurations are assigned. Model 1 – The Boarding House Sunny Rooms Pink Rooms kitchen Time: Manager’s Code: 1:00 pm 1s1 kitchen 7:00 pm Time: Manager’s Code: 1s2 2s2 2p6 3s1 kitchen 3:00 pm 1s2 2s2 2p2 kitchen 9:00 pm 1s2 2s2 2p6 3s2 3p1 kitchen 5:00 pm 1s2 2s2 2p4 kitchen 11:00 pm 1s2 2s2 2p6 3s2 3p3 1. Examine the Boarding House diagrams of Model 1. Match each of the symbols below with their meaning. III I. bunk bed for boarders ____a. I ____b. II. manager’s code for the # of boarders in the house II ____c. 1s2 2s2 2p6 3s1 III. boarder 2. How many boarders were in the boarding house at 5:00 pm? 9 boarders 3. Examine the diagrams in Model 1 and corresponding manager’s codes. Use the appropriate symbol to indicate where on the manager’s codes each piece of information is found. 1s2 2s2 2p4 floor number (arrows) type of room (circles) number of boarders (arrows) 4. The Manager of this boarding house has some very strict rules on how beds will be rented out for the night. Examine the diagrams in Model 1 to determine the correct phrase which will complete the Manger’s set of rules. Circle the answer that you select. a) The boarding house will rent out beds on the _______ floor first. 1st 2nd 3rd b) Boarders are only allowed to double up in a bunk when __________________. there is an even number of boarders in the room. all bottom bunks are occupied. c) The next floor of rooms will be opened for boarders only when __________ on the floor below are occupied half of the bunks at least one of the rooms all of the bunks d) The pink room on a floor will be opened for boarders only when ____________ all of the lower bunks in the sunny room on that floor are occupied. all of the bunks in the sunny room on that floor are occupied. the sunny room on that floor is open. 5. Provide the Manager’s Code and a Boarding House diagram when there are 12 boarders present. Manager's Code: 1s^2 2s^2 2p^6 3s^2 Model 2 – Ground State Orbital Diagrams & Electron Configurations Increasing Energy 3p 3s 3p 3s 2p 3p 3s 2p 2p 2s 2s 2s 1s 1s 1s Hydrogen 1s1 Carbon 1s2 2s2 2p2 3p Oxygen 1s2 2s2 2p4 3p 3s 3s 2p 3p 3s 2p 2p 2s 2s 2s 1s 1s 1s Sodium 1s2 2s2 2p6 3s1 Aluminum 1s2 2s2 2p6 3s2 3p1 Phosphorus 1s2 2s2 2p6 3s2 3p3 6. Examine the orbital diagrams and electron configurations of Model 2. Match each of the symbols below with their meaning. III ____a. I. single electron I ____b. II. pair of electrons with opposite spin II III. atomic orbital (region of space where an electron is likely to be found) ____c. IV ____d. V ____e. IV. sublevel (several orbitals of equivalent energy) 1s2 2s2 2p4 V. electron configuration 7. a) In the orbital diagram for oxygen in Model 2, how many electrons are present? 8 electrons b) Explain how you know that your answer to part a) is the correct number of electrons for an oxygen atom. In the diagram for oxygen, there are 8 arrows which represent the electrons. 8. Examine the orbital diagrams and electron configurations in Model 2. Use the appropriate symbol to indicate where on the manager’s codes each piece of information is found. 1s2 2s2 2p4 sublevel (circle) number of electrons (arrow) Read This! The lowest energy arrangement of electrons in an atom is called the ground state. 9. The 2s and 2p sublevels are very close in energy, as are the 3s and 3p sublevels. Explain how the orbital diagram for sodium confirms that the 3s sublevel is lower in energy than the 3p sublevel. It confirms this because in the 3p there are 3 atomic orbitals than in the 3s where there is only one, so when the electrons take up the space, there would be more in the 3p than the 3s. 10. Ground state electron configurations can be predicted by a strict set of rules known as the Rules of Aufbau (meaning filling up). Examine the diagrams in Model 2 to determine the correct phrase which will complete each rule. Circle the correct answer. a) Based on where a single electron is placed, the lowest energy electron in an atom is found in the ________ sublevel. 1s 2s 3s b) Electrons will occupy a p-orbital only after ____________ the previous s-orbital is half full. the previous s-orbital is completely full. the previous s-orbital is empty. c) Electrons can begin to occupy sublevels with the next highest integer designation (e.g., 2 vs. 1, 3 vs. 2) only after _____________ on the sublevel below are occupied. half of the orbitals. at least one of the orbitals all of the orbitals 11. The Pauli Exclusion Principle describes the restriction on the placement of electrons into the same orbital. The Pauli Exclusion Principles can be expressed as: “If two electrons occupy the same orbital they must have ____________(circle the correct answer). the same spin opposite spins 12. Hund’s Rules describes how electrons are distributed among orbitals of the same sublevel when there is more than one way to distribute them. Hund’s Rules consist of two important ideas. Based on the model, circle the correct answer. a) Electrons will only pair up in an orbital when __________________. there is an even number of electrons in the sublevel. all orbitals in the sublevel have one electron. b) When single electrons occupy different orbitals of the same sublevel, __________________. they all have the same spin. they all have different spins their spins are random. 13. For each of the symbols below from Model 2, provide the name (or description) of the analogous component from the Boarding House model: a) Sunny Rooms Pink Rooms Boarder Boarders 1s2 2s2 2p4 Manager's code for the number of boarders in the house b) What characteristic of electrons is not well represented by the Boarding House model? The pair of electrons with opposite signs c) How could the Boarding House Model be modified to better represent the relative energies of s and p sublevels? The model could put the s sublevel on its own and not together with the p sublevel 14. Below are three answers generated by students in response to the prompt: “Provide an orbital energy level diagrams for the ground state of a nitrogen atom.” In each case, indicate whether the answer is right or wrong, and if it is wrong, indicate what the error is. 3p 3p 3s 2p 2p 2s 1s a. 3p 3s 3s 2p 2s This is wrong because the single electrons, This is right This is wrong because 1s moved on to the next sublevel without 2s 1s the electrons are'nt b. filling up the orbitals on 2p before they put the c. pairing up. other spin 15. Below are three answers generated by students in response to the prompt: “Provide an orbital energy level diagrams for the ground state of a carbon atom.” In each case, indicate whether the answer is right or wrong, and if it is wrong, indicate what the error is. 3p 3p 3s 2p 2p 2s 2s This is wrong because there shouldn't be 3 1s a. 3p 3s 3s should only be 2 This is right This is wrong because the singular electron in facing 1s single electrons on the 2p sublevel, there 2p 2s b. 1s down on the 2p sublevel c. and the middle one has no electron. Extension Questions: Model 3 – Excited State Orbital Diagram for an Atom of Element X 3p 3s 2p 2s 1s 16. a) Based on Model 3, how many electrons are there in 1 atom of element X? 10 electrons b) Provide the electron configuration that corresponds to the orbital diagram in Model 3. 1s^2 2s^2 2p^5 3s^1 c) Explain how you know (other than from the title!) that the orbital diagram in Model 3 is not a ground state orbital diagram. I know because the rules are different since in the 2p sublevel, there's only 5 electrons instead of 6 and it moved on to the next sublevel. d) Is the arrangement of electrons in the orbital diagram in Model 3 higher in energy or lower in energy than the ground state electron configuration of element X? Explain your reasoning. It's a higher energy level because the electrons are shown on a higher level in the orbitals e) Identify element X and provide its ground state electron configuration. Element X is would be neon and the ground state electron configuration is 1s^2 2s^2 2p^6 Read This! An excited state electron configuration is any electron configuration for an atom that contains the correct total number of electrons but is not the ground state electron configuration. 17. Each of the three orbital diagrams shown below describes an excited state of an atom of a different element. In each case: provide the corresponding electron configuration (a), identify the element (b), and then provide the ground state electron configuration for an atom of that element (c). 3p 3p 3s 3s 2p 3p 3s 2p 2p 2s 2s 2s 1s 1s 1s 1s^2 2s^1 2p^3 3p^1 a._____________________ a.________________________ 1s^2 2s^2 2p^6 3s^1 3p^1 1s^2 2s^2 2p^3 3p^6 a.________________________ Nitrogen Magnesium b.________________________ Aluminum b.________________________ b._____________________ 1s^2 2s^2 2p^3 c._____________________ 1s^2 2s^2 2p^3s^2 c.________________________ 1s^2s^2 2p^6 3s^2 3p^1 c.________________________ 18. For each of the excited state electron configurations given below, identify the corresponding element and then provide two more possible excited state configurations. a) b) c) 1s2 2s1 2p2 1s2 2s2 2p2 3s2 3p1 1s2 2p2 a: Boron/ 2s^2 2p^1 b: Fluorine/ [He] 2s^2 2p^5 c: Beryllium/ [He] 2s^2