Unit 3 Exam Guide. Bohr Models Practice drawing a few Bohr models: K Group #? 1 Number of valence electrons? 1 Period #? 4 Number of rings?

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1 Name: Hr: Unit 3 Exam Guide These are the main ideas for this exam. Check your understanding: 1 I am confused and need help; 2 I think I have this, but need to practice more; 3 I ve got this and could explain it to someone else. I can draw a Bohr model for an atom. I can tell the number of valence electrons an element has from the periodic table. I can read a Bohr model and tell the period and group of the element. I know the trend for atomic radius in a group and a period. I know the trend for ionization energy in a group and a period. I can compare two elements and determine the larger atomic radius or ionization energy. I can explain the reason for the change in atomic radius or ionization energy. I can explain how force of attraction between an electron and protons in a nucleus changes with distance and more particles (within a group or a period). I can compare two elements and determine which has the greater force of attraction. I can read information from a chart or graph. I can identify the s, p, d, and f blocks of the periodic table. I know how many electrons each orbital block can hold. I can compare two orbitals and explain which one is higher energy. I can read an electron configuration and tell the energy level, the orbital, and number of electrons in the orbital. I can locate an element on the periodic table from an electron configuration. I can write a long electron configuration for an element. I can write an abbreviated electron configuration for an element. I can read an orbital diagram and know how to fill it. Bohr Models Practice drawing a few Bohr models: K Group #? 1 Number of valence electrons? 1 Period #? 4 Number of rings? 4 F Group #? 17 or 7A Number of valence electrons? 7 Period #? 2 Number of rings? _2

2 Si Group #? 14 or 4A Number of valence electrons? 4 Period #? 3 Number of rings? 3 How many valence electrons are in these representative element groups? Alkali Metals (Group 1) 1 Halogens (Group 17 or 7A) 7 Alkaline Earth Metals (Group 2) 2 Group 15 _ 5 State the trends for atomic radius: Atomic radius increases down a group and to the left in a period. Which element has a larger atomic radius? Al or Cl Why? Cl has more protons so a greater attractive force and a smaller radius; Al has less force of attraction and a larger radius Rb or I Mg or Ra Why? Ra has more energy levels so the distance is greater from valence electron to nucleus Te or S State the trends for ionization energy: Ionization energy increases to the top of a group and to the right in a period Which element has the larger ionization energy? O or Se Why? O has a greater force of attraction so it is harder to remove valence electrons Ga or Br Why? Br has more protons resulting in a greater force of attraction, so it is harder to remove valence electrons Li or C K or Rb

3 How does the force of attraction change between an electron and the protons in a nucleus if the distance increases? The force of attraction decreases as distance increases. Where does this change occur on the periodic table? Going down a group, the distance between the protons in the nucleus and the valence electrons increases. How does the force of attraction change between an electron and the protons in a nucleus if the number of protons increases? The force of attraction increases as the number of protons increases. Where does this change occur on the periodic table? Going across a period, the number of protons increases within an energy level and the force of attraction increases. Which element has the greatest force of attraction between the valence electron and the nucleus? State why for each one. C or Sn Closer to the nucleus Ba or Be Closer to the nucleus Mn or Br Greater number of protons within an energy level S or Te Closer to the nucleus Use the force of attraction to explain the trend in atomic radius within a group. The force of attraction decreases with additional levels of electrons and distance and radius increases. Use the force of attraction to explain the trend in atomic radius across a period. The force of attraction increases from left to right due to increasing numbers of protons, so the radius of the atoms decreases. Use the force of attraction to explain the trend in ionization energy within a group. The force of attraction is greatest near the top of a group because the electrons are close to the nucleus, which increases the amount of energy required to remove a valence electron. Use the force of attraction to explain the trend in ionization energy across a period. The force of attraction increases across a period with increasing numbers of protons, which increases the energy required to remove a valence electron.

4 Why is the radius for element 16 so much smaller than element 15? There is one more proton in element 16 so there is a stronger force of attraction than in element 15. Why is element 52 so much larger than element 8? There are more energy levels and more electrons between the nucleus and the valence electrons, so the force of attraction is less for element 8. How many electrons can be in each energy sublevel (orbital block) for the given energy level? 2s 2 3p 6 4d 10 5f 14 Does the number of electrons in an s orbital change if it is 2s or 3s or 4s? No. Each s sublevel holds 2 electrons. Why do we not write the 3d orbital in the 3rd row of the periodic table? The 3d sublevel is higher energy than the 4s sublevel. We write the periodic table in order of energy. Which is higher energy? 2s or 5s 3d or 3p 5s or 4d 5f or 7s

5 Reading the electron notation 3p 5 state each of the following: a. What is the energy level? 3 b. What is the sublevel? p c. How many electrons are present in the notation? _5 What is the maximum number of electrons in energy level 1? 2 What is the maximum number of electrons in energy level 2? 8 What is the maximum number of electrons in energy level 3? 8 (18 also acceptable since 3d has the principal energy level 3) ** When both reading and writing electron configurations, watch your periodic table. Remember that Lanthanide begins 4f and Actinide begins 5f. ** Write both full (long hand) and abbreviated (short hand) electron configurations for each of the following: Phosphorus (15) full: 1s 2 2s 2 2p 6 3s 2 3p 3 [Ne] 3s 2 3p 3 Selenium (34) full: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 4 [Ar] 4s 2 3d 10 4p 4 Yttrium (39) full: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 1 [Kr] 5s 2 4d 1 Thallium (81) full: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 6 7s 2 5f 2 [Rn] 7s 2 5f 2

6 Name the elements with the following electron configurations: 1s 2 2s 2 2p 6 3s 2 3p 2 Si 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 5 Br 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 3 Nb 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 1 Cs 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 6 6s 2 4f 14 5d 10 6p 3 Bi [Ne] 3s 2 3p 1 [Ar] 4s 2 3d 7 [Xe] 6s 2 4f 13 Al Co Tm Remember when filling orbital diagrams to fill lowest energy first and show unpaired spins until you must begin pairing. Scandium (21)Paired arrows (up/down) in 1s, 2s, 2p, 3s, 3p, 4s, and one up arrow in 3d Phosphorus (15) Paired arrows (up/down) in 1s, 2s, 2p, 3s, and three individual up arrows in 3p)