Model 1: Orbitals. 1. What is an atomic orbital? What are the four different orbitals?

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1 Name: Date: Period: POGIL: Electron Configuration and Orbitals Model 1: Orbitals The quantum mechanical model determines the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus. Electrons are located in orbitals (different than Bohr!) in the electron cloud. An atomic orbital is a region of space in which there is a high probability of finding an electron. There are four orbitals, s, p, d, and f which are found in different energy levels called principle quantum numbers. Below is a table summarizing this idea. Be aware that we go all the way up to principle energy level of 7, however, it does become a bit more complex. We use the energy level numbers and orbitals in a code called electron configuration which helps us express the location of an electron with high probability. Key Content Questions: 1. What is an atomic orbital? What are the four different orbitals? 2. What do you notice about the sublevels as you increase in energy levels? 3. Are all orbitals found in each sublevel? s Orbital The s orbital is a spherical shape and can only have 2 electrons. It is the first orbital in an energy level to be filled when writing electron configurations. The s orbital only has one orientation, seen in the picture to the right. This orbital is found in all energy levels. (s=sphere memory clue!)

2 p Orbital The p orbital looks like a peanut (p=peanut). This orbital has 3 orientations and can therefore hold 6 total electrons. The p orbitals and orientations are shown on the right. The orientations refer to how many different ways the orbital can orient itself in space. This orbital is found in energy levels 2-7. d Orbital The d orbital looks like a double peanut (d=double peanut) and can hold 10 electrons total. This has 5 orientations, one of which is shown to the right. This orbital is found in energy levels 3-6. f Orbtial The f orbital looks like a flower (f=flower) and can hold 14 electrons. This has 7 orientations, one of which is shown to the right. This orbital is found in energy levels 4 and 5. Key Content Questions: 4. Fill out the following table: Orbital Memory Clue to help with appearance How many orientations does each orbital have? How many electrons fit in each orbital? What energy levels are each orbital found in? s p d f 5. What do you notice about the orientations and the number of electrons in each orbital (meaning, is there some kind of mathematical relationship?)

3 Model 2: Writing Electron Configuration The periodic table is that it is sectioned off by orbitals, or region of space in which there is a high probability of finding an electron. There are four orbitals, s, p, d, and f which are found in different energy levels called principle quantum numbers. We use the energy level numbers and orbitals in a code called electron configuration which helps us express the location of an electron with high probability. We can actually use the periodic table to write our electron configurations. The first row is energy level 1, the second is energy level 2, and so on. *NOTE: The d and f orbital energy levels do not follow the energy levels by row like s and p, so pay attention to those differences S orbitals Periods 1 2 d orbitals p orbitals f orbitals Key Content Questions: Look at the periodic table above, all the orange boxes indicates the principle energy level and the atomic orbital that the outer electrons in that specific element occupies. 6. Look at Helium (He), is it part of the s orbital or p orbital? 7. The d orbital starts in the 4th row, or 4th energy level. However, what energy level (period number) does d actually start with? 8. How many elements do all the s orbital span (go across) in each period? (circle your answer) a) 2 b) 6 c) 10 d) 14

4 9. How many elements do all the p orbital span (go across) in each period? (circle your answer) a) 2 b) 6 c) 10 d) How many elements do all the d orbital span (go across) in each period? (circle your answer) a) 2 b) 6 c) 10 d) How many elements do all the f orbital span (go across) in each period? (circle your answer) a) 2 b) 6 c) 10 d) What do your answers to #8-11 correspond to (look back at the table in question 4 of model 1). 13. What element can be found by an ending electron configuration of 2p 3? (Hint: go to the 2p row and count 3 elements in) 14. What element can be found by an ending electron configuration of 3s 2? (Hint: go to the 3s row and count 2 elements in) 15. What element can be found by an ending electron configuration of 3d 6? (Hint: go to the 3d row and count 6 elements in)

5 One trend we see in the periodic table is that it is sectioned off by orbitals. We can actually use the periodic table to write our electron configurations. The first row is energy level 1, the second is energy level 2, and so on. The d and f orbital energy levels do not follow the energy levels by row like s and p, so pay attention to those differences. Example 1: Writing the electron configuration for Boron (B) Helium (He) was moved to help exemplify how to use the periodic table for electron configuration. Ground State Electron Configuration for Boron is: 1s 2 2s 2 2p 1 Example 2: Writing the electron configuration for Calcium (Ca). # of electrons Ground State Electron Configuration for Calcium is: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 Key Content Questions: 16. Look at example 1 above, what do the little numbers (superscripts) at the top represent? 17. Write the ground state electron configuration for the Boron element in example 1 above (yes, just re-write it here). B: 18. Write the ground state electron configuration for the Calcium element in example 2 above (yes, just re-write it here) Ca: 19. Locate and Write the ground state electron configuration for oxygen (O). Follow the same pattern as the examples above. O:

6 20. Locate and Write the ground state electron configuration for sodium (Na). Follow the same pattern as the examples above. Na: 21. Locate and Write the ground state electron configuration for aluminum (Al). Follow the same pattern as the examples above. Al: 22. Locate and Write the ground state electron configuration for phosphorus (P). Follow the same pattern as the examples above. P:

7 Model 3: Filling Orbital Diagrams 23. Examine Model 3 above. Compare the electron configuration for the elements in the model to your answers in key question # Correct any that you got wrong in a different color pen. 24. Examine the orbital diagrams and electron configurations in Model 2. Match each symbol below with its meaning. 25. Consider the orbital diagram for oxygen (O) in Model 3. a. How many electrons are present in the orbital diagram?

8 b. Based on its position in the periodic table, explain how you know that your answer to part a is the correct number of electrons for oxygen. 26. Examine the orbital diagrams and electron configurations in Model 2. Using the following electron configuration: a. Underline the energy levels. b. Circle the sublevels. c. Draw a box around the numbers of electrons. 27. The 2s and 2p sublevels are very close in energy, as are the 3s and 3p sublevels. Explain how the orbital diagram for sodium (Na) confirms that the 3s sublevel is lower in energy than the 3p sublevel. 28. The lowest potential energy arrangement of electrons in an atom is called the ground state. Ground state electron configurations can be predicted by a strict set of rules known as the Aufbau principle ( aufbau means filling up). Examine the diagrams in Model 3 and the statements below to determine the phrase that best describes each rule. Circle the correct answer. a. Based on where a single electron is placed, the lowest potential energy electron in an atom is found in the sublevel. 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 energy levels with the next highest integer designation (e.g., 2 vs. 1, 3 vs. 2) only after on the energy level below it are occupied. half of the orbitals at least one of the orbitals all of the orbitals 29. The Pauli exclusion principle describes the restriction on the placement of electrons into the same orbital. The Pauli exclusion principle can be expressed as: If two electrons occupy the same orbital, they must have. Circle the correct answer. the same spin opposite spins 30. Hund s rule describes how electrons are distributed among orbitals of the same sublevel when there is more than one way to distribute them. Hund s rule consists of two important ideas. Based on Model 2, circle the correct answer to each statement. a. Electrons will pair up in an orbital only when i. there is an even number of electrons in the sublevel ii. all orbitals in the same sublevel have one electron

9 b. When single electrons occupy different orbitals of the same sublevel,. i. they all have the same spin ii. they all have different spins iii. their spins are random 31. Define each of the following rules electrons follow when filling orbitals: Aufbau Principle: Pauli Exclusion Principle: Hund s Rule: 32. Below are three answers from three different students in response to the prompt: Write the orbital diagram for the ground state of Nitrogen (N) atom. In each case, indicate whether the answer is right or wrong. If it is wrong, explain the error using the rules from above. Ground state electron configuration for Nitrogen (N): Right or Wrong Right or Wrong Right or Wrong 33. Complete the ground state electron configuration and orbital diagram for the following.

10 34. Write the element represented by the following electron configurations (hint you only need to look at the last orbital and use your periodic table for example, I know a configuration that ends in 3s 1 is sodium because it is in the third row in the s block and is the first element in that block). a. 1s 2 2s 1 : b. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 5d 10 4p 6 5s 2 : c. 1s 2 2s 2 2p 6 3s 2 3p 3 : d. 6p 4 :

11 Model 4: Shorthand/Nobel Gas Electron Configuration Instead of writing out every orbital for electron configurations, we have a shorter way! It is called the noble gas or shorthand electron configuration. In this configuration, you do not need to write out the inner electrons, only the outer electrons called valence electrons. To account for the inner electrons, put the nobel gas in the row before the element you are writing the configuration for in brackets, and then write the rest of the configuration. For example, here is the longhand and shorthand configurations for iron: Longhand à Shorthand à There are a few things to keep in mind: 1. Hydrogen and helium do not have a shorter configuration than their longhand configurations 2. Nobel gases cannot represent themselves in brackets you still must go back to the previous nobel gas and then write out the rest of the configuration. 35. Write the shorthand electron configurations for the following elements: a. Magnesium (Mg): b. Zinc (Zn): c. Tin (Sn): d. Krypton (Kr): e. Cesium (Cs):