POGIL 6 Key Periodic Table Trends (Part 2)

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1 Honors Chem Block Name POGIL 6 Key Periodic Table Trends (Part 2) is a measure of the ability of an atom s nucleus to attract electrons from a different atom within a covalent bond. A higher electronegativity value correlates to a stronger pull on the electrons in a bond. This value is only theoretical. It cannot be directly measured in the lab. 1. Using the definition above, select the best visual representation for electronegativity. Explain your reasoning. A B C D 2. Using the above definition and your knowledge of the atomic structure and Coulombic attraction predict the electronegativity trend in a group on the Periodic Table. Explain your thinking. EN trend in a group goes up. As you go up the group, the number of shells goes down, electrons become closer to the nucleus, the attraction gets stronger, so does ability to attract electrons in a bond. 3. Predict electronegativity trend in a period on the Periodic Table. Explain your thinking. EN trend in a period goes right. As you go right, the Zeff increases, the attraction force increases, so does ability to attract electrons in a bond. 4. Follow the same instruction you used for plotting the Atomic Radius and the Ionization Energy graphs, to build the graph for and check your predictions (this time you need to use the fourth column from the data). 5. Look at your graph. What is happening to electronegativity as the atomic number increases? As the atomic number increases, the EN goes up and down, then up again and down periodically. 6. Which element has the highest electronegativity? F 7. Are noble gases included into this trend? Explain. Noble gases cannot be included into EN trend for two reasons: 1. Noble gases do not make bonds (except for bottom three) 2. They do not attract electrons, since they have the most stable configuration (full valence shell).

2 8. Arrange the following atoms in order of increasing electronegativity: Si, Cl, K, Al K, Al, Si, Cl 9. Below is the summary chart for three trends. You may have noticed that not all of the data provided in this chart followed the trends. Why is it still beneficial for chemists to understand as many periodic trends as they can? 1 H Main Group Elements 37 (look at the decoding on the bottom of the page) N/A 3 Li 4 Be 5 B 6 C 7 N 8 O 9 F 2 He 10 Ne N/A 11 Na 12 Mg 13 Al 14 Si 15 P 16 S 17 Cl 18 Ar N/A 19 K 20 Ca 31 Ga 32 Ge 33 As 34 Se 35 Br 36 Kr N/A Atomic Number Element Symbol Electron Shell Diagram Atomic Radius (pm) 1st Ionization Energy (kj/mol) Note: The transition elements and f- block elements have been removed from the periodic table here to ease the analyses of the trends

3 Reactivity of Metals Metal reactivity is an atom s ability to lose electrons. Metal atoms that lose electrons easily are more reactive than atoms that lose electrons less easily. 10. Write the core electron configurations for Na, Mg, and Al Na: [Ne] 3s 1 Mg: [Ne] 3s 2 Al: [Ne] 3s 2 3p What characteristic are we using to explain any trend in a period of the Periodic Table? We use Z eff to explain any trend in a period 12. Describe the trend in that characteristic from left to right across period 3 In a period three (like in any period) from left to right Z eff increases 13. Using your knowledge about atomic structure, Coulombic attraction and based on the trend in Z eff, describe the metal reactivity trend (ability of atoms to lose electrons) in a period MR trend in a period goes left. As you go left the Z eff decreases, so does the force of attraction of outer electrons making it easier to lose them; metals become more reactive 14. Write the core electron configuration for the first 4 metals in group 1A Li: [He] 2s 1 Na: [Ne] 3s 1 K: [Ar] 4s 1 Rb: [Kr] 5s What characteristic are we using to explain any trend in a group of the Periodic Table? We use number of shells to explain any trend in a group 16. Describe the trend in that characteristic from the top to the bottom in a group From the top to the bottom in a group the number of shells increases 17. Based on this trend, describe the metal reactivity trend (ability of atoms to lose electrons) in a group As you go down the group the MR increases since the more levels an atoms has, the further away the valence electrons are from the nucleus. The force of attraction goes down because of the increased shielding. The electrons become loose, the metal reactivity goes up.

4 18. Hydrogen is a non-metal. Justify the placement of Hydrogen in group 1A despite its nonmetal characteristics. Hydrogen has one valence electron, like all alkali metals. The most common ion of hydrogen has a charge of +1, the same as ions made by alkali metals 19. Is there another place on the Periodic Table where hydrogen could be placed? Explain. Yes, Hydrogen can be placed at the top of group 7A, because, like all halogens, hydrogen is a nonmetal and is able to gain one electron to get a noble gas configuration Reactivity of Non-metals Non-metal reactivity is an atom s ability to gain electrons. Atoms that gain electrons easily are more reactive than atoms that gain electrons less easily. 20. Write the core electron configuration for N, O, and F N: [He] 2s 2 2p 3 O: [He] 2s 2 2p 4 F: [He] 2s 2 2p Describe the trend in Z eff from left to right across period 3 As you go from left to right on the PT, Z eff increases 22. Based on the trend in Z eff, describe the trend in ability of atoms to gain electrons from left to right across period 3 As Z eff increases, so does the force of attraction and ability to gain electrons from left to right on the PT 23. Based on the trend in ability of atoms to gain electrons, make a conclusion about the nonmetal reactivity trend in a period. Nonmetal reactivity increases from left to right on the PT. 24. Does the trend in non-metal reactivity include the noble gases? Explain. No, noble gases cannot be included into non-metal reactivity trend, they are extremely stable and do not react 25. Write the core electron configuration for the first 3 elements in group 7A F: [He] 2s 2 2p 5 Cl: [Ne] 3s 2 3p 5 Br: [Ar] 4s 2 3d 10 4p 5

5 26. Describe the trend in number of energy levels in a group As you go down the group, the number of shells increases 27. Based on the trend in number of energy levels, describe the trend in ability of atoms to gain electrons from top to bottom in group 7A As the number of shells goes up, the ability to gain electrons goes down, because the force of attraction weakens with distance and shielding increase 28. Based on the trend in ability of atoms to gain electrons, make a conclusion about the nonmetal reactivity trend in a group. Nonmetal reactivity trend goes up in the group. The fewer shells an atom has, the smaller shielding, the stronger the attraction force, the easier it is for the atom to gain additional electrons. So, it is more reactive. 29. The two diagrams below can summarize each of the trends discussed in Periodicity POGILs. Write atomic radius, ionization energy, electronegativity, metal reactivity, and non-metal reactivity under the appropriate diagram. Ionization energy Non-metal reactivity Atomic radius Ionic Radius Metal reactivity