General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 3.7 Orbital Diagrams and Electron Configurations Chapter 3 Atoms and Elements © 2013 Pearson Education, Inc. Lectures

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Order of Filling Energy levels are filled with electrons  in order of increasing energy.  beginning with quantum number n = 1.  beginning with s followed by p, d, and f in each energy level. 2

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Energy Diagram for Sublevels 3

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Orbital Diagrams 4 An orbital diagram shows  orbitals as boxes in each sublevel.  electrons in orbitals as vertical arrows.  electrons in the same orbital with opposite spins (up and down vertical arrows). Example: Orbital diagram for Li 1s 2 filled 2s 1 half-filled 2p empty

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Order of Filling Electrons in an atom  fill the lowest energy level and orbitals first,  fill orbitals in a particular sublevel with one electron each until all orbitals are half full, and then  fill each orbital using electrons with opposite spins. 5

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Writing Orbital Diagrams 6 The orbital diagram for carbon has 6 electrons:  2 electrons are used to fill the 1s orbital.  2 more electrons are used to fill the 2s orbital.  1 electron is used in two of the 2p orbitals so they are half-filled, leaving one p orbital empty. Electron arrangements in orbitals in energy levels 1 and 2.

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Learning Check Write the orbital diagrams for each of the following: 1. nitrogen 2. oxygen 3. magnesium 7

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Solution 8 Write the orbital diagrams for each of the following: 1. nitrogen 1s 2s 2p 2. oxygen 1s 2s 2p 3. magnesium 1s 2s 2p 3s

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Electron Configuration An electron configuration  lists the filled and partially filled energy levels in order of increasing energy.  lists the sublevels filling with electrons in order of increasing energy.  uses superscripts to show the number of electrons in each sublevel.  for neon is as follows: number of electrons = 10 1s 2 2s 2 2p 6 9

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Period 1 Configurations 10 In Period 1, the first two electrons enter the 1s orbital.

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Period 2 Configurations 11 In Period 2,  lithium has 3 electrons –2 in the 1s and 1 in the 2s.  beryllium has 4 electrons –2 in the 1s and 2 in the 2s.  boron has 5 electrons –2 in the 1s, 2 in the 2s, and 1 in the 2p.  carbon has 6 electrons –2 in the 1s, 2 in the 2s, and 2 in the 2p.

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Abbreviated Configurations In an abbreviated configuration,  the symbol of the noble gas is in brackets, representing completed sublevels.  the remaining electrons are listed in order of their sublevels. Example: Chlorine has the following configuration: 1s 2 2s 2 2p 6 3s 2 3p 5 [Ne] The abbreviated configuration for chlorine is [Ne]3s 2 3p 5. 12

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Period 2 Configurations 13

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Period 3 Configurations 14

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Learning Check 1. The correct electron configuration for nitrogen is A. 1s 2 2p 5 B. 1s 2 2s 2 2p 6 C. 1s 2 2s 2 2p 3 2. The correct electron configuration for oxygen is A. 1s 2 2p 6 B. 1s 2 2s 2 2p 4 C. 1s 2 2s 2 2p 6 3. The correct electron configuration for calcium is A. 1s 2 2s 2 2p 6 3s 2 3p 6 3d 2 B. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 C. 1s 2 2s 2 2p 6 3s 2 3p 8 15

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Solution 1. The correct electron configuration for nitrogen is C. 1s 2 2s 2 2p 3 2. The correct electron configuration for oxygen is B. 1s 2 2s 2 2p 4 3. The correct electron configuration for calcium is B. 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 16

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Learning Check Write the electron configuration and abbreviated configuration for each of the following elements: 1. Cl 2. S 3. K 17

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Solution Write the electron configuration and abbreviated configuration for each of the following elements: 1. Cl 1s 2 2s 2 2p 6 3s 2 3p 5 [Ne]3s 2 3p 5 2. S 1s 2 2s 2 2p 6 3s 2 3p 4 [Ne]3s 2 3p 4 3. K 1s 2 2s 2 2p 6 3s 2 3p 6 4s 1 [Ar]4s 1 18

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Electron Configurations and the Periodic Table The periodic table consists of sublevel blocks arranged in order of increasing energy.  Groups 1A and 2A= s block  Groups 3A to 8A= p block  Transition Elements (This sublevel is (n-1), 1 less than the period number.)= d block  Lanthanides/Actinides (This sublevel is (n-2), 2 less than the period number.)= f block 19

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Sublevel Blocks 20

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Guide to Using Sublevel Blocks 21

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Writing Electron Configurations Using the periodic table, write the electron configuration for silicon. Solution: Period 11s block1s 2 Period 22s → 2p blocks 2s 2 2p 6 Period 3 3s → 3p blocks 3s 2 3p 2 (at Si) Writing all the sublevel blocks in order gives the following: 1s 2 2s 2 2p 6 3s 2 3p 2 22

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Electron Configurations of the d Level The 4s orbital has a lower energy than the 3d orbitals. 23

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Writing Electron Configurations Using the periodic table, write the electron configuration for manganese. Solution: Period 11s block1s 2 Period 22s → 2p block 2s 2 2p 6 Period 3 3s → 3p block 3s 2 3p 6 Period 44s → 3d block4s 2 3d 5 (at Mn) Writing all the sublevel blocks in order gives the following: 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 5 24

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Learning Check 1. What are the last two sublevel blocks in the electron configuration for Co? A. 3p 6 4s 2 B. 4s 2 4d 7 C. 4s 2 3d 7 2. What are the last three sublevel blocks in the electron configuration for Sn? A. 5s 2 5p 2 4d 10 B. 5s 2 4d 10 5p 2 C. 5s 2 5d 10 5p 2 25

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Solution 1. What are the last two sublevel blocks in the electron configuration for Co? C. 4s 2 3d 7 2. What are the last three sublevel blocks in the electron configuration for Sn? B. 5s 2 4d 10 5p 2 26

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Learning Check Using the periodic table, write the electron configuration and abbreviated configuration for each of the following elements: 1. Zn 2. Sr 3. I 27

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Solution 1. Zn 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 [Ar]4s 2 3d Sr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 [Kr]5s 2 3. I 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 5s 2 4d 10 5p 5 [Kr]5s 2 4d 10 5p 5 28

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Learning Check Give the symbol of the element that has 1. the abbreviated configuration [Ar]4s 2 3d four 3p electrons. 3. two electrons in the 4d sublevel. 4. the electron configuration 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2. 29

© 2013 Pearson Education, Inc. Chapter 3, Section 7 Solution Give the symbol of the element that has 1. the abbreviated configuration [Ar]4s 2 3d 6. Fe 2. four 3p electrons. S 3. two electrons in the 4d sublevel. Zr 4. the electron configuration Ti 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2. 30