Chapter 7 Ionic and Metallic Bonding 7.2 Ionic Bonds and 7.1 Ions 7.2 Ionic Bonds and Ionic Compounds 7.3 Bonding in Metals Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Group in Periodic Table Will if form a Cation or Anion? CHEMISTRY & YOU Do Now: Complete the table below in your notebook. Element Group in Periodic Table # of Valence Electrons Will if form a Cation or Anion? Ionic Charge? Li I S Ca N Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Group in Periodic Table Will if form a Cation or Anion? CHEMISTRY & YOU Do Now: Complete the table below. Element Group in Periodic Table # of Valence Electrons Will if form a Cation or Anion? Ionic Charge? Li 1A 1 Cation 1+ I 7A 7 Anion 1- S 6A 6 2- Ca 2A 2 2+ N 5A 5 3- Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Formation of Ionic Compounds Composed of cations & anions. Electrically neutral - Total positive charge = Total negative charge Ions held together by ionic bonds - electrostatic forces (opposite charges attract) Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Formation of Ionic Compounds What happens when Sodium and Chloride react? Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Formation of Ionic Compounds Ionic Bonds - NaCl When sodium and chlorine react to form a compound, the sodium atom transfers its one valence electron to the chlorine atom. Sodium and chlorine atoms combine in a one-to-one ratio, and both ions have stable octets. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Formation of Ionic Compounds What ionic compound do you think would form between the following elements? a) Potassium and Oxygen b) Magnesium and Nitrogen Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

The formula of the compound formed is K2O. Sample Problem 7.1 a. In order to have a filled valence shell, the oxygen atom must gain two electrons. These electrons come from two potassium atoms, each of which loses one electron. K • • • O + K+ 2– The formula of the compound formed is K2O. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

The formula of the compound is Mg3N2. Sample Problem 7.1 b. Each nitrogen atom needs three electrons to have an octet, but each magnesium atom can lose only two electrons. Three magnesium atoms are needed for every two nitrogen atoms. • • • N 3– + Mg2+ Mg The formula of the compound is Mg3N2. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Formation of Ionic Compounds Formula Units The chemical formula of an ionic compound refers to a ratio known as a formula unit. A formula unit is the lowest whole-number ratio of ions in an ionic compound. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Formation of Ionic Compounds Formula Units For sodium chloride, the lowest whole-number ratio of the ions is 1:1 (one Na+ ion to each Cl– ion). The formula unit for sodium chloride is NaCl. Although ionic charges are used to derive the correct formula, they are not shown when you write the formula unit of the compound. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Formation of Ionic Compounds Ionic compounds do not exist as discrete units, but as collections of positively and negatively charged ions arranged in repeating patterns. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Formation of Ionic Compounds The structure of an ionic compound is called a crystalline structure. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Use electron dot structures to determine the formula of the ionic compound formed when calcium reacts with fluorine. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Use electron dot structures to determine the formula of the ionic compound formed when calcium reacts with fluorine. • • F • + Ca2+ – Ca The formula is CaF2. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Properties of Ionic Compounds Most ionic compounds are crystalline solids at room temperature. High Melting Points Can conduct electric current when melted or dissolved in water Composed of a metal & nonmetal Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Properties of Ionic Compounds When sodium chloride is melted, the orderly crystal structure breaks down. To (+) electrode To (–) electrode Inert metal electrodes Flow of electrons Current meter Power source Cl– Na+ If a voltage is applied across this molten mass, cations migrate freely to one electrode and anions migrate to the other. This movement of electrons allows electric current to flow between the electrodes through an external wire. Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

Properties of Ionic Compounds Ionic compounds also conduct electric current if they are dissolved in water. When dissolved, the ions are free to move about in the solution. https://www.youtube.com/watch?v=acefiRwXDos Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.

END OF 7.2 Copyright © Pearson Education, Inc., or its affiliates. All Rights Reserved.