General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.1 Chapter 3 Atoms and Elements 3.6 Electron Energy Levels

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.2 Electromagnetic Radiation Electromagnetic radiation  is energy that travels as waves through space  is described in terms of wavelength and frequency  moves at the speed of light in a vacuum speed of light = 3.0 x 10 8 m/s

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.3 Electromagnetic Spectrum The electromagnetic spectrum  arranges forms of energy from lowest to highest  arranges energy from longest to shortest wavelengths  shows visible light with wavelengths from 700–400 nm

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.4 Learning Check 1. Which of the following has the shortest wavelength? A. microwaves B. blue light C. UV light 2. Which of the following has the lowest energy? A. red light B. blue lightC. green light

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.5 Solution 1. Which of the following has the shortest wavelength? C. UV light 2. Which of the following has the lowest energy? A. red light

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Gamma Ray

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.7 Spectra White light that passes through a prism  is separated into all colors that together are called a continuous spectrum  gives the colors of a rainbow

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc. Neon Light

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.9 Example of Atomic Spectra

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.10 Energy Level Changes  An electron absorbs energy to “jump” to a higher energy level.  When an electron falls to a lower energy level, energy is emitted.  In the visible range, the emitted energy appears as a color.

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.11 Atomic Spectrum An atomic spectrum consists of  lines of different colors formed when light from a heated element passes through a prism  photons emitted when electrons drop to lower energy levels

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.12 Electron Energy Levels Electrons are arranged in specific energy levels that  are labeled n = 1, n = 2, n = 3, and so on  increase in energy as n increases  have the electrons with the lowest energy in the first energy level (n = 1) closest to the nucleus

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.13 In each of the following energy level changes, indicate if energy is 1) absorbed, 2) emitted, or 3) not changed. A. An electron moves from the first energy level (n = 1) to the third energy level (n = 3). B. An electron falls from the third energy level to the second energy level. C. An electron moves within the third energy level. Learning Check

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.14 In each of the following energy level changes, indicate if energy is 1) absorbed, 2) emitted, or 3) not changed. A. An electron in an atom moves from the first energy level (n = 1) to the third energy level (n = 3). 1) absorbed B. An electron falls from the third energy level to the second energy level. 2) emitted C. An electron moves within the third energy level. 3) not changed Solution

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.15 Sublevels There is a limit to how many electrons can occupy each energy level 2n 2 ( n = priniciple quantum number). Sublevels  contain electrons with the same energy  are found within each energy level.  are designated by the letters s, p, d, and f The number of sublevels is equal to the value of the principal quantum number (n).

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.16 Number of Sublevels

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.17 Energy of Sublevels In any energy level  the s sublevel has the lowest energy  the s sublevel is followed by the p, d, and f sublevels (in order of increasing energy)  higher sublevels are possible, but only s, p, d, and f sublevels are needed to hold the electrons in the atoms known today

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.18 Orbitals An orbital  is a three-dimensional space around a nucleus where an electron is most likely to be found  has a shape that represents electron density (not a path the electron follows)  can hold up to 2 electrons  contains two electrons that must spin in opposite

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.19 s Orbitals An s orbital  has a spherical shape around the nucleus  increases in size around the nucleus as the energy level n value increases  is a single orbital found in each s sublevel

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.20 p Orbitals A p orbital  has a two-lobed shape  is one of three p orbitals that make up each p sublevel  increases in size as the value of n increases

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.21 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.

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.22 Electrons in Each Sublevel

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.23 Learning Check Indicate the number and type of orbitals in each of the following: A. 4s sublevel B. 3d sublevel C. n = 3

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.24 Solution A. 4s sublevel one 4s orbital B. 3d sublevel five 3d orbitals C. n = 3 one 3s orbital, three 3p orbitals, and five 3d orbitals

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.25 Learning Check The number of A. electrons that can occupy a p orbital is 1) 12) 23) 3 B. p orbitals in the 2p sublevel is 1) 12) 23) 3 C. d orbitals in the n = 4 energy level is 1) 12) 33) 5 D. electrons that can occupy the 4f sublevel is 1) 22) 63) 14

General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.26 Solution The number of A. electrons that can occupy a p orbital is 2) 2 B. p orbitals in the 2p sublevel is 3) 3 C. d orbitals in the n = 4 energy level is 3) 5 D. electrons that can occupy the 4f sublevel is 3) 14