Modern Chemistry Chapter 4 Arrangement of Electrons in Atoms Sections 1-3 The Development of a New Atomic Model The Quantum Model of the Atom Electron Configurations

The Quantum Model of the Atom Section 2 The Quantum Model of the Atom Chapter 4 Section 2 The Quantum Model pages 104-110

Chapter 4 Section 2 The Quantum Model pages 104-110 Electrons As Waves Electrons can have wave and particle characteristics (like light). Waves (electrons) confined to a space can have only certain frequencies The frequencies correspond to Bohr’s orbits. Louis de Broglie Chapter 4 Section 2 The Quantum Model pages 104-110

Chapter 4 Section 2 The Quantum Model pages 104-110 Electrons As Waves This is confirmed by experiments Electrons, like waves, can be bent, diffracted and have interference Diffraction: the bending of a wave as it passes through a small opening Interference: when waves overlap. Chapter 4 Section 2 The Quantum Model pages 104-110

The Heisenberg Uncertainty Principle Involves the detection of electrons To detect an electron a photon is used The photon interacts with the electron and changes its course There is uncertainty in trying to locate an electron. Chapter 4 Section 2 The Quantum Model pages 104-110

The Heisenberg Uncertainty Principle It is impossible to determine simultaneously both the position and velocity of an electron or any other particle. Chapter 4 Section 2 The Quantum Model pages 104-110

The Schrödinger Wave Equation Developed an equation that treats electrons as waves Proved the quantization of electron energies Quantum theory: describes mathematically the wave properties of electrons and other small particles Chapter 4 Section 2 The Quantum Model pages 104-110

The Schrödinger Wave Equation Solutions to the equations are wave functions. Wave functions give the probability of finding electrons. Electrons do not travel in neat orbits. Electrons exist in regions called orbitals. Orbital: a three dimensional region around the nucleus that indicates the probable location of electrons. Chapter 4 Section 2 The Quantum Model pages 104-110

Heisenbery Uncertainty Principle Animation Chapter 4 Section 2 The Quantum Model pages 104-110

Atomic Orbitals and Quantum Numbers Quantum numbers specify the properties of atomic orbitals and the properties of electrons in the orbital. The first three numbers result from the solution to Schrodinger’s wave equation. Chapter 4 Section 2 The Quantum Model pages 104-110

Principle Quantum Number 1 Symbol = n Energy Level n = 1, 2, 3, 4, 5, 6, 7 (whole numbers) As n increases the electron’s energy and average distance from the nucleus increases. Chapter 4 Section 2 The Quantum Model pages 104-110

Angular Momentum Quantum Number 2 Symbol = l Shape of orbital (sublevel) l = s, p, d, f A sublevel is made up of a certain number of orbitals Chapter 4 Section 2 The Quantum Model pages 104-110

Atomic Orbitals and Quantum Numbers Sublevel Orbitals Electrons s 1 2 p 3 6 d 5 10 f 7 14 Chapter 4 Section 2 The Quantum Model pages 104-110

Magnetic Quantum Number 3 Symbol = m Orientation around the nucleus m = x, y, z, xy, yz, xz Chapter 4 Section 2 The Quantum Model pages 104-110

Chapter 4 Section 2 The Quantum Model pages 104-110 Spin Quantum Number 4 Symbol = ms Spin State of the electron m = +1/2, -1/2 When electrons spin they produce a magnetic field. Two electrons can exist in one orbital. Each electron must have an opposite spin state. Chapter 4 Section 2 The Quantum Model pages 104-110

# of electrons on a energy level 7s2 7p6 7d10 7f14 7g 7h 7i 6s2 6p6 6d10 6f14 6g 6h 5s2 5p6 5d10 5f14 5g 4s2 4p6 4d10 4f14 3s2 3p6 3d10 2s2 2p6 1s2 # of electrons on a energy level 32e- = 2+6+10+14 18e- = 2 + 6 + 10 8e- = 2 + 6 2e- = 2 in the s orbital Chapter 4 Section 2 The Quantum Model pages 104-110

Electron Configurations Section 3 Electron Configurations Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 Aufbau principle Pauli exclusion principle Hund’s Rule Noble Gas Noble Gas configurations Section 3 Vocabulary Chapter 4 Section 3 Electron Configurations pages 110-122

Rules Governing Electron Configurations Aufbau Principle An electron occupies the lowest energy orbital that can receive it Less energy is required for electrons to pair up in the 4s than the 3d. Aufbau: German for construction Chapter 4 Section 3 Electron Configurations pages 110-122

Aufbau Principle Animation Chapter 4 Section 3 Electron Configurations pages 110-122

Sublevel Filling Order 7s 7p 7d 7f 7g 7h 7i 6s 6p 6d 6f 6g 6h 5s 5p 5d 5f 5g 4s 4p 4d 4f 3s 3p 3d 2s 2p 1s Sublevel Filling Order Chapter 4 Section 3 Electron Configurations pages 110-122

Rules Governing Electron Configurations Pauli Exclusion Principle No two electrons in the same atom can have the same set of four quantum numbers. Electrons must have opposite spin states Two electrons can exist in an orbital. Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 Pauli and Bohr Chapter 4 Section 3 Electron Configurations pages 110-122

Pauli Exclusion Principle Animation Chapter 4 Section 3 Electron Configurations pages 110-122

Rules Governing Electron Configurations Hund’s Rule Orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin state. Repulsion between electrons is minimized. Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 3d 4d 5s 5p 6s 5d 6p 6d 7s 4f 5f Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 PRACTICE Page 113 # 1 & 2 Write the electron configurations for the following elements: Ne, Na, Mg, Ar, K p. 113 Chapter 4 Section 3 Electron Configurations pages 110-122

Orbital Notation Animation Chapter 4 Section 3 Electron Configurations pages 110-122

Representing Electron Configurations Orbital Notation      . 1s 2s 2p Which element is this? How does this show Hund’s rule? Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 Orbital Diagram for Si orbital 14 electrons electron (-1/2 spin) 1s 2s 2p 3s 3p electron (+1/2 spin) sublevel Chapter 4 Section 3 Electron Configurations pages 110-122

Shapes of s, p and d orbitals Image Chapter 4 Section 3 Electron Configurations pages 110-122

Representing Electron Configurations Orbital Notation      . 1s 2s 2p Electron Configurations 1s2 2s2 2p3 Use superscripts instead of lines and arrows. Chapter 4 Section 3 Electron Configurations pages 110-122

Reading Electron Configuration Notation Animation Chapter 4 Section 3 Electron Configurations pages 110-122

Electron Configurations For Manganese – 25 electrons 1s 2s 2p 3s 3p 4s 3d 2 2 6 2 6 2 5 number of electrons in the sublevel sublevel Chapter 4 Section 3 Electron Configurations pages 110-122

Electron Configuration Animation p. xx Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 PRACTICE Page 113 # 1 & 2 Write the electron configurations for the following elements: Ne, Na, Mg, Ar, K p. 113 Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Second Period 3Li = 1s2 2s1 6C = 1s2 2s2 2p2 Inner shell electrons Highest occupied energy level C = 4 valence electrons Li = 1 valence electron Valence electrons: electrons occupying the highest energy level in an atom Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Third Period 10Ne = 11Na = 12Mg = 18Ar = 19K = 1s2 2s2 2p6 1s2 2s2 2p6 3s1 1s2 2s2 2p6 3s2 1s2 2s2 2p6 3s2 3p6 1s2 2s2 2p6 3s2 3p6 4s1 Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Third Period Look! It’s neon! 10Ne = 11Na = 12Mg = 18Ar = 19K = 1s2 2s2 2p6 1s2 2s2 2p6 3s1 1s2 2s2 2p6 3s2 1s2 2s2 2p6 3s2 3p6 1s2 2s2 2p6 3s2 3p6 4s1 Ar?! Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Third Period 10Ne = 11Na = 12Mg = 18Ar = 19K = 1s2 2s2 2p6 1s2 2s2 2p6 3s1 1s2 2s2 2p6 3s2 1s2 2s2 2p6 3s2 3p6 1s2 2s2 2p6 3s2 3p6 4s1 [Ne] [Ne] [Ar] Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Third Period 10Ne = 11Na = 12Mg = 18Ar = 19K = 1s2 2s2 2p6 [Ne] 3s1 [Ne] 3s2 1s2 2s2 2p6 3s2 3p6 [Ar] 4s1 Chapter 4 Section 3 Electron Configurations pages 110-122

Noble Gas Notation Animation Chapter 4 Section 3 Electron Configurations pages 110-122

Noble Gas Configuration Find the noble gas with an atomic number closest to but less than the element’s atomic number. Find the next sublevel after that noble gas Fill in sublevels with the “leftover” electrons. (atomic # of element – atomic # of noble gas) Chapter 4 Section 3 Electron Configurations pages 110-122

Noble Gas Configurations 2p6 3p6 4p6 5p6 6p6 Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 3d 4d 5s 5p 6s 5d 6p 6d 7s 4f 5f Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Fourth Period Deviations 24Cr = 24Cr = [Ar] 3d5 4s1 unpaired electrons give a more stable arrangement with a lower energy 29Cu = 29Cu = [Ar] 3d10 4s1 No explanation for either [Ar] 4s2 3d4 WRONG!!! [Ar] 3d9 4s2 WRONG!!! Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Fourth Period Even though the d sublevel fills before the p sublevel, the s sublevel is moved to be with the p sublevel. 53I = [Kr] 5s2 4d10 5p5 is written as… 53I = [Kr] 4d10 5s2 5p5 The sublevels on the same energy level are together. It also shows the valence electrons. Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Fifth Period Y [Kr] 4d1 5s2 Zr [Kr] 4d2 5s2 Nb [Kr] 4d3 5s2 Mo [Kr] 4d4 5s2 Tc [Kr] 4d5 5s2 Ru [Kr] 4d6 5s2 Rh [Kr] 4d7 5s2 Pd [Kr] 4d8 5s2 Ag [Kr] 4d9 5s2 Cd [Kr] 4d10 5s2 expected deviations Nb [Kr] 4d4 5s1 Mo [Kr] 4d5 5s1 Tc [Kr] 4d6 5s1 Ru [Kr] 4d7 5s1 Rh [Kr] 4d8 5s1 Pd [Kr] 4d10 Ag [Kr] 4d10 5s1 p.120 Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 PRACTICE Page 121 #1-4 p. 113 Chapter 4 Section 3 Electron Configurations pages 110-122

Elements of the Sixth Period 4f and 5d are very close in energy causing many deviations Look at the configurations on the periodic table on the back cover of the book. Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 PRACTICE Page 122 #1 & 2 p. 113 1. answer 2. answer 3. answer Chapter 4 Section 3 Electron Configurations pages 110-122

Chapter 4 Section 3 Electron Configurations pages 110-122 Section 3 Homework Chapter 4 Section 3 Electron Configurations pages 110-122