![© 2014 Pearson Education, Inc.
Learning Check
Use the periodic table to give the symbol of the
element with each of the following electron
configurations.
A. 1s2
2s2
2p6
3s2
3p6
4s2
3d7
B. [Ar] 4s2
3d10
4p5](https://image.slidesharecdn.com/chemsection5-250121132740-b59f97c3/85/chem_section_5-5_powerpointttttttttt-ppt-18-320.jpg)
![© 2014 Pearson Education, Inc.
Solution
Use the periodic table to give the symbol of the
element with each of the following electron
configurations.
A. 1s2
2s2
2p6
3s2
3p6
4s2
3d7
Element is cobalt (Co).
B. [Ar] 4s2
3d10
4p5
Element is bromine (Br).](https://image.slidesharecdn.com/chemsection5-250121132740-b59f97c3/85/chem_section_5-5_powerpointttttttttt-ppt-19-320.jpg)
chem_section_5.5_powerpointttttttttt.ppt
- 1. © 2014 Pearson Education, Inc. Chapter 5 Lecture Basic Chemistry Fourth Edition Chapter 5 Electronic Structure and Periodic Trends 5.5 Electron Configurations and the Periodic Table Learning Goal Write the electron configuration for an atom using the sublevel blocks on the periodic table.
- 2. © 2014 Pearson Education, Inc. Periodic Table Blocks Different sections or blocks within the periodic table correspond to the s, p, d, and f sublevels. We can “build” the electron configurations of atoms by reading the periodic table in order of increasing atomic number.
- 3. © 2014 Pearson Education, Inc. Periodic Table Blocks
- 4. © 2014 Pearson Education, Inc. The s Block The s block includes • hydrogen and helium • elements in Group 1A (1) • elements in Group 2A (2) Elements in the s block have their final one or two electrons in an s orbital.
- 5. © 2014 Pearson Education, Inc. The p Block The p block consists of elements in Group 3A (13) to Group 8A (18). There are six p block elements in each period, because three p orbitals can hold up to six electrons.
- 6. © 2014 Pearson Education, Inc. The d Block The d block contains transition elements. The d sublevels are one less (n – 1) than the period number. There are 10 elements in each d block, because five d orbitals can hold up to 10 electrons.
- 7. © 2014 Pearson Education, Inc. The f Block The f block contains inner transition elements, two rows at the bottom of the periodic table. The f sublevel is two less than the period number. There are 14 elements in each f block, because there are seven f orbitals that can hold up to 14 electrons.
- 8. © 2014 Pearson Education, Inc. Electron Configurations, Using the Periodic Table Using the periodic table, write the electron configuration for silicon. Solution Period 1 1s block 1s2 Period 2 2s → 2p blocks 2s2 2p6 Period 3 3s → 3p blocks 3s2 3p2 (Si) Writing all the sublevel blocks in order gives 1s2 2s2 2p6 3s2 3p2
- 9. © 2014 Pearson Education, Inc. Guide to Writing Electron Configurations
- 10. © 2014 Pearson Education, Inc. Sample Problem Use the sublevel blocks on the periodic table to write the electron configuration for chlorine. Step 1 Locate the element on the periodic table. Chlorine (atomic number 17) is in Group 7A (17) and Period 3.
- 11. © 2014 Pearson Education, Inc. Sample Problem Use the sublevel blocks on the periodic table to write the electron configuration for chlorine. Step 2 Write the filled sublevels in order, going across each period.
- 12. © 2014 Pearson Education, Inc. Sample Problem Use the sublevel blocks on the periodic table to write the electron configuration for chlorine. Step 3 Complete the configuration by counting the electrons in the last occupied sublevel block. The electron configuration for chlorine (Cl) is 1s2 2s2 2p6 3s2 3p5
- 13. © 2014 Pearson Education, Inc. Period 4 The 4s sublevel fills before the 3d sublevel because the electrons in the 4s sublevel are slightly lower in energy than those in the 3d sublevel. This order occurs again in Period 5, when the 5s fills before the 4d sublevel, and in Period 6, when the 6s fills before the 5d sublevel.
- 14. © 2014 Pearson Education, Inc. Period 4
- 15. © 2014 Pearson Education, Inc. Period 4
- 16. © 2014 Pearson Education, Inc. Some Exceptions in Sublevel Block Order In filling the 3d sublevel, exceptions occur for chromium and copper. •In Cr the 3d sublevel is close to being half- filled, which is more stable; thus one of the 4s electrons moves to the 3d sublevel. 4s 3d
- 17. © 2014 Pearson Education, Inc. Some Exceptions in Sublevel Block Order • In Cu the 3d sublevel is close to being filled, which is more stable; thus one of the 4s electrons moves to the 3d sublevel. 4s 3d
- 18. © 2014 Pearson Education, Inc. Learning Check Use the periodic table to give the symbol of the element with each of the following electron configurations. A. 1s2 2s2 2p6 3s2 3p6 4s2 3d7 B. [Ar] 4s2 3d10 4p5
- 19. © 2014 Pearson Education, Inc. Solution Use the periodic table to give the symbol of the element with each of the following electron configurations. A. 1s2 2s2 2p6 3s2 3p6 4s2 3d7 Element is cobalt (Co). B. [Ar] 4s2 3d10 4p5 Element is bromine (Br).