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Name _____________KEY________________ Period____________________ Date Periodic Trends ATOMIC RADIUS 1. What trend in atomic radius do you see as you go down a group/family on the periodic table? Atomic Radius increases as you go DOWN a group/family.2. What causes this trend? Each period you go down increases the energy levels surrounding the atom (you can draw Bohr Models to show this is true). For example, H and Li (in group 1A) both have 1 valence e-, but H’s is in the first energy level, and Li’s is in the 2nd. This trend continues down each family/group.3. What trend in atomic radius do you see as you go across a period/row on the periodic table? Across (LR) a period, atomic radius decreases.4. What causes this trend? As you go across a period (LR) all of the elements have their valence e- in the same energy level (you can draw a Bohr Model to show this is true). As you add more p+, you are increasing the positive force in the nucleus that attracts the e-, and so the e- are pulled in closer to the nucleus. 5. Circle the atom in each pair that has the largest atomic radius. a) [Al] B b) [S] O c) [Br] Cl d) [Na] Al e) [O] F f) Mg [Ca] 6. Put the following elements in order from smallest to largest atomic radius and explain why: C, O, Sn, Sr.O<C<Sn<Sr O will have a smaller radius than C because it is in the same period, but has more p+, and so holds its e- in more closely. C is smaller than Sn because it is in the same group, but has less energy levels filled with e-, so it can hold them in closer to the nucleus. Sn is smaller than Sr because it is in the same period, but has more p+, so can hold its e- in more closely. 7. How does the ionic radius of a nonmetal compare with its atomic radius? Non-metals tend to GAIN e-. When another e- is added to the valence shell, it adds more negative charge. This causes all of the other e- to spread out more, because increasing the negative charges causes a greater repulsive force. IONIZATION ENERGY8. Define ionization energy The amount of energy needed for an atom to lose an e- 9. What trend in ionization energy do you see as you go down a group/family on the periodic table? As you go down a group, I.E. DECREASES.10. What causes this trend? Think about the reason the radius gets bigger: adding more energy levels/electron shells. If my valence e- are held further away from the attractive forces in the nucleus (the p+), then they don’t feel as strong a pull from the nucleus, and are easier to remove.11. What trend in ionization energy do you see as you go across a period/row on the periodic table? As you go across (LR) a period, I.E. INCREASES.12. What causes this trend? Again, think about why atomic radius gets smaller across a period: more protons have a larger attractive force acting on a certain number of energy levels. With a larger attractive force, it is more difficult to pull the tightly held e- away from the nucleus. ELECTRONEGATIVITY 13. Define electronegativity The tendency for an atom to attract an e- in a chemical bond.14. What trend in electronegativity do you see as you go down a group/family on the periodic table? As you go down a group, electronegativity DECREASES15. What causes this trend? Think about atomic radius: we know the radius gets bigger as you go down a group, so the valence shell gets further from the attractive force (p+) in the nucleus, so the valence shell feels a weaker attractive force, and e- aren’t as easily pulled in. 16. What trend in electronegativity do you see as you go across a period/row on the periodic table? As you go across (LR) a period, electronegativity INCREASES.17. What causes this trend? Think about atomic radius: more p+ create a stronger attractive force, causing the e- to be held more closely to the nucleus. Since the valence shell is closer to that (stronger) attractive force, it is easier to pull in e- from other atoms. 18. Circle the atom in each pair that has the greater electronegativity. a) Ca [Ga] b) Li [O] c) [Cl] S d) [Br] As e) Ba [Sr] f) [O] SGENERAL QUESTIONS19. Which group (column) tends to form +1 ions? ___Group 1A (Alkali Metals)__________________20. Which group tends to form +2 ions? ____Group 2A (Alkaline Earth Metals)_________________21. Which group tends to form -1 ions? ____Group 7A (Halogens)___________________________22. Which group tends not to form ions or react? ____Group 8A (Noble Gases)_________________23. Define metallic character. Properties of metals: (1) Good conductors of heat/electricity (2) Usually solid at room temperature, except Mercury (3) Ductile (can be pulled into thin wire) (4) Malleable (can be hammered into thin sheets) (5) Lustrous (shiny)24. Based on the concept of periodic trends, answer the following questions for these atoms: Li, Be, Mg, Na. Be able to defend your answers. Which element has the highest electronegativity? Be, has the smallest atomic radius, so valence shell is closest to nucleus, where attractive force (p+) is. Which element has the lowest ionization energy? Na, has largest atomic radius, s valence shell is far from source of attractive force (the p+ in the nucleus). Which element is the largest atom? Na, has the largest atomic radius because it has the most energy levels, and few enough p+ to not be able to pull in the e- as close as the other elements25. Based on the concept of periodic trends, answer the following questions for these atoms: P, S, Cl, F. Be prepared to defend your answers. Which element has the highest electronegativity? F, has the smallest atomic radius because it has 2 energy levels of e-, with the most p+. This means that the valence shell is closest to the attractive force (the p+) in the nucleus. Which element has the lowest ionization energy? P, three energy levels, and the least amount of p+ in that period means it has the lowest attractive force, and the valence shell is held further out from the nucleus. Which element has the largest ion? P (see reasoning above).Based on the concept of periodic trends, answer the following questions for these atoms: Au, Zn, S, Si. Be able to defend your answers. Which element has the highest electronegativity? S, has the least amount of energy levels filled with electrons, and so the valence shell is closer to the attractive force (p+) in the nucleus. This means that the e- will feel the strongest pull from this atom. Which element has the lowest ionization energy? Au. Has the most energy levels filled with e-, so the valence shell is farthest from the nucleus. This means its outer (valence) e- are not as tightly held and require less energy to be pulled away. Which element has the largest atom? Au (see reasoning above, shells are farthest from nucleus)Complete the following chart:KMgNeNClSiAtomic #19121071714Period432233Group #1A2A8A5A7A4AFamily name(if any)Alkali MetalsAlkaline Earth MetalsNoble Gasesn/aHalogensn/a# of valence e-128574# protons ALWAYS the same as atomic #!!!19121071714Metal, nonmetal, or metalloid?MetalMetalNon-metalNon-metalNon-metalMetalloidConducts electricity? (yes/no)YesYesNoNoNoSemi-conductorState at room temperature?Don’t worry about this Ion Formed?(positive, negative, none, varies)PositivePositiveNone (full valence shell)NegativeNegativeVaries (we didn’t cover this)_______G______ metal_______C______ chlorine_______D______ metalloid_______B______ transition elements_______E______ group 1_______F______ noble gases_______A______ group 2alkaline earth metalsmetals with unpredictable propertiesa halogenmake good semiconductorsalkali metalshas a full outer energy level (shell)loses electrons in bondingInstructions Below the diagram, create a key which connects arrows with the following periodic trends: electronegativity, ionization energy, atomic radius. Specify “increasing” or “decreasing” for each trend. More than one trend can associate with each arrow.502920243840Electronegativity & Ionization Energy increases // Atomic radius decrease00Electronegativity & Ionization Energy increases // Atomic radius decrease27622585725AA52146202332355EN & I.E. increase // atomic radius decrease00EN & I.E. increase // atomic radius decrease-13989051854835EN & I.E. increase // Atomic radius increase00EN & I.E. increase // Atomic radius increase-2762244343400DD6153150171450CC-276224257175BB647700355788Electronegativity & Ionization Energy decrease // Atomic radius increase020000Electronegativity & Ionization Energy decrease // Atomic radius increase ................
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