Week 8 CHE iAL Explore Lesson 1 - Ionic Bonding

Page 2: Identifying Mistakes in Ionic Theory

• Definition of Ionic Compounds:

  • Mistake: Compounds of metals with metals are incorrectly stated.

  • Correction: Compounds like sodium chloride are actually composed of metal and non-metal ions.

• Ions Formation:

  • Mistake: Metal atoms lose at least 2 electrons to become positive ions (anions) is incorrect.

  • Correction: Metal atoms lose electrons to form positive ions (cations).

• Sodium Ion Formation:

  • Mistake: Sodium ion is referred to as Na2+.

  • Correction: It should be Na+ (sodium loses one electron).

• Chlorine Ion Formation:

  • Mistake: Chlorine ions are described inaccurately.

  • Correction: Chlorine gains one electron to form Cl- (chloride ion).

Page 5: Introduction to Ionic Bonding

• Ionic Bonding:

  • Definition: An ionic bond involves the electrostatic attraction between positively and negatively charged ions that results from electron transfer.

  • Key Players: Cations (positive ions) and Anions (negative ions).

Page 6: Learning Objectives

• 3.1 Interpret evidence for ions:

  • Focus on electron density maps and migration of ions.

• 3.2 Describe ion formation:

  • Emphasizes loss and gain of electrons.

• 3.3 Draw dot-and-cross diagrams:

  • Illustrate electrons in cations and anions.

• 3.5 Ionic bonding:

  • Understand strong net electrostatic attraction between ions.

Page 8: Classwork Instruction

• Dot-and-Cross Diagrams:

  • Tasks include drawing for:

    • Lithium fluoride,

    • Magnesium chloride,

    • Lithium oxide,

    • Calcium sulfide.

  • Question: Why do metals form positive ions while non-metals form negative ions?

Page 9: Ionic Bonding Explanation

• Definitions and Reactions:

  • Explain the term 'ionic bonding'

  • Example reaction of calcium with fluorine: Ca(s) + F2(g) --> CaF2(s).

  • Requirement to use dot-and-cross diagrams to demonstrate electronic changes.

Page 10: Comparison of Ionic Bond Strength

• Question (a):

  • Explanation of why ionic bonding strength in sodium fluoride exceeds that of potassium fluoride.

• Question (b):

  • Comparison of ionic bonding strength in calcium oxide vs. potassium fluoride.

Page 11: Assessment Overview

• Assessment Topics:

  • L.O. 3.1: Evidence for Ions (5 points)

  • L.O. 3.2: Formation of Ions (4 points)

  • L.O. 3.3 and 3.5: Ionic Bonding (6 points)

Page 12: Plenary Questions

• Electron Transfer During Reaction:

  • What occurs when sodium reacts with fluorine to form sodium fluoride?

  • What are the relevant equations?

Page 16: Answers to Classwork Questions

• Dot-and-Cross Diagrams:

  • Lithium fluoride: Li+ F-

  • Magnesium chloride: Mg2+ Cl2-

  • Calcium sulfide: Ca2+ S2-

• Explanation:

  • Metals have 1, 2, or 3 outer shell electrons, making it easier to lose them.

  • Non-metals have 5, 6, or 7 outer shell electrons that they gain to form ions.

Page 17: Explanation of Ionic Bonding

• Definition:

  • Ionic bonding is the strong electrostatic forces between oppositely charged ions, represented in diagrams.

Page 18: Strength of Ionic Bonds

• Question 3(a):

  • Na+ is smaller than K+, resulting in closer ion packing and stronger attraction.

• Question 3(b):

  • Calcium has a charge density (2+) compared to potassium (1+), leading to significantly greater electrostatic attraction.