General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 3.6 Electron Arrangement in Atoms Chapter 3 Atoms and Elements 2013 Pearson Education, Inc. Lectures 2013 Pearson Education, Inc. Chapter 3, Section 6 Electrons and Reactivity Atoms contain a very small nucleus packed with neutrons and positively charged protons. a large volume of space around the nucleus that contains the negatively charged electrons. It is the electrons that determine the physical and chemical properties of atoms. 2 2013 Pearson Education, Inc. Chapter 3, Section 6 Electron Energy Levels Electrons surround the nucleus in specific energy levels. Each energy level has a principal quantum number (n). The lowest energy level, which is closest to the nucleus, is labeled n = 1. The second-lowest energy level is labeled n = 2, the third n = 3, and so on. 3 2013 Pearson Education, Inc. Chapter 3, Section 6 Electron Energy Levels 4 Electron energy levels increase in energy and number as electrons get farther away from the nucleus. The higher the electron energy levels, the more electrons they hold. the more energy the electrons have. 2013 Pearson Education, Inc. Chapter 3, Section 6 Sublevels Within each energy level, we have sublevels that contain electrons with identical energy. are identified by the letters s, p, d, and f. The number of sublevels within a given energy level is equal to the value of the principal quantum number, n. 5 2013 Pearson Education, Inc. Chapter 3, Section 6 Energy Levels and Sublevels 6 2013 Pearson Education, Inc. Chapter 3, Section 6 Energy of Sublevels Within any energy level, the s sublevel has the lowest energy. the p sublevel follows and is slightly higher in energy. the d sublevel follows the p and is slightly higher in energy than the p. the f sublevel follows the d and is slightly higher in energy than the d. 7 2013 Pearson Education, Inc. Chapter 3, Section 6 Orbitals 8 Each electron sublevel consists of orbitals, which are regions where there is the highest probability of finding an electron. have their own unique three-dimensional shape. can hold up to 2 electrons. 2013 Pearson Education, Inc. Chapter 3, Section 6 s Orbitals 9 We know that s orbitals have a spherical shape, centered around the atoms nucleus. The s orbitals get bigger as the principal quantum number, n, gets bigger. The s orbitals can hold up to 2 electrons that must spin in opposite directions. 2013 Pearson Education, Inc. Chapter 3, Section 6 p Orbitals 10 There are three p orbitals in each energy level, starting with energy level 2. They have a two-lobed shape, much like tying a balloon in the middle, and can hold 2 electrons. are labeled x, y, and z. increase in size as the value of n increases. 2013 Pearson Education, Inc. Chapter 3, Section 6 Sublevels and Orbitals Each sublevel consists of a specific number of orbitals. An s sublevel contains one s orbital. A p sublevel contains three p orbitals. A d sublevel contains five d orbitals. An f sublevel contains seven f orbitals. 11 2013 Pearson Education, Inc. Chapter 3, Section 6 Electron Capacity in Sublevels 12 2013 Pearson Education, Inc. Chapter 3, Section 6 Learning Check Indicate the number and type of orbitals in each of the following: 1. 4s sublevel 2. 3d sublevel 3. n = 3 13 2013 Pearson Education, Inc. Chapter 3, Section 6 Solution Indicate the number and type of orbitals in each of the following: Number Type 1. 4s sublevel 1 4s orbital 2. 3d sublevel 5 3d orbitals 3. n = 31 3s orbitals, and 3 3p orbitals, and 5 3d orbitals 14 2013 Pearson Education, Inc. Chapter 3, Section 6 Learning Check The number of 1. electrons that can occupy a p orbital is A. 1B. 2C p orbitals in the 2p sublevel is A. 1B. 2C d orbitals in the n = 4 energy level is A. 1B. 3C electrons that can occupy the 4f sublevel is A. 2B. 6C 2013 Pearson Education, Inc. Chapter 3, Section 6 Solution The number of 1. electrons that can occupy a p orbital is B p orbitals in the 2p sublevel is C d orbitals in the n = 4 energy level is C electrons that can occupy the 4f sublevel is C