Ionic Bonds: Formation and Naming

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Objective

Students will be able to explain how ionic bonds are formed and name ionic compounds through taking notes, performing an activity, doing whiteboards, and performing practice questions.

Big Idea

Ionic compounds are formed when electrons are transferred from metals to nonmetals.

Introduction

In this lesson students delve into ionic bonding through taking notes and practicing in several ways including bond with a classmate, whiteboards, and individual practice.

  • This lesson aligns with NGSS Performance Expectation: HS-PS1-2: Construct and revise an explanation for the outcome of a simple chemical reaction based on the outermost electron states of atoms, trends in the periodic table, and knowledge of the patterns of chemical properties.
  • This lesson aligns with NGSS Science and Engineering Practice 2: Developing and using models because students learn to model the formation of ionic compounds both through showing electron transfer and using a shortcut.

Within this lesson there are several resources used.

  1. For the bond with a classmate activity students need to have a set of ions and cations with which to bond.  I use one color index card for anions and one for cations.  I then attach a Popsicle stick to each card. Here is a picture of a cation and anion.
  2. For the whiteboard practice students need access to whiteboards, erasers, and dry-erase markers. 

Engage

15 minutes

I engage students in the lesson in two ways. 

1. I have students fill out a Venn Diagram to review the three types of bonds. 

  • I pass out the Venn Diagram to students.
  • I explain to them how to fill out a Venn Diagram.
  • I have them use the list at the top of characteristics to place into the diagram
  • I have them skip properties that we have not yet discussed or they are not sure about so that they will come back to them later. 
  • This video shows how I do this.
  • This is a copy of a filled in diagram.

2. I have students perform Periodic Table Aerobics to review the components of the three types of bonds. 

  • I have a copy of the Periodic Table on the first slide of the PowerPoint.
  • See the reflection on Kinesthetic Learners in Chemistry to see what this entails.

I then tell students that we are going to spend the day learning more about ionic compounds.

Explain

50 minutes

In this portion of the lesson I teach students about ionic compounds through having them fill out a unit3 lec1 notes graphic organizer while I present the Unit 3 Lecture 1 PowerPoint.

  1. The lesson begins with an explanation of some properties of ionic compounds.  Some of these are review from the labs and reading but a good place to tie into what students have already seen in regards to ionic bonds.
  2. Students are then shown how to model the transfer of electrons in ionic compounds through using Lewis structures.  This video shows me explaining how to draw Lewis structures including the transfer of electrons.  Students are then given time to practice several problems.
  3. I then explain to students how to figure out the formula of ionic compounds with a shortcut using oxidation numbers.  This video shows me explaining how the shortcut works.  Students are then given time to practice these types of problems
  4. For the last part of the explanation part of the lesson I teach students how to name ionic compounds.  Students are then given time to practice naming as well.

This is a copy of a student's filled in notes.

Elaborate part I

20 minutes

To reinforce the formation of ionic compounds from ions and the naming of ionic compounds I have students perform an activity. 

  • This activity "Bond with a Classmate" is found on the third page of the notes.
  • I also have the directions on the last slide of the PowerPoint.
  • Students are directed to walk around the classroom and find other students to bond with.
  • Students then write the ionic compound that is formed and name the compound. 
  • Student then go on and find a new partner.
  • This video shows me explaining how to do this to my students.

Elaborate part II

15 minutes

To reinforce how to name ionic compounds I have students perform naming whiteboard practice. I have students work in pairs and each pair needs one whiteboard, one dry erase marker, and one dry eraser.  I have students work with partners to encourage them to discuss why they think that a certain answer is correct.  I periodically remind them to switch partners in terms of who is doing the writing throughout the whiteboard session. 

This is the PowerPoint I use.

1. I put up a problem on the PowerPoint and then have students hold up their answers. 

2. I either give thumbs up or down and if they get it incorrect they should retry. 

3. After most students answer I go onto the next answer.  If it is one that many get wrong I go over why the correct answer is correct either by myself explaining or having a student explain how they determined the answer. 

The most common mistake that students make is forgetting to use roman numerals for transition metals and not correctly writing the number of each type of atom. 

Here are two examples of student mistakes for Fe2O3 (Iron (III) oxide).  Notice that one group did not use roman numerals (ionic-mistake-1), and the other group used the wrong roman numeral (ionic-mistake-2).

If you do not have access to whiteboards you can have your school order some such as these at Office Max or you can also have students write answers on a sheet protector with a piece of paper in the middle.

Evaluate

As a way to check for student understanding I have them do the last page of the notes graphic organizer  as Homework Practice. 

I check the homework for completion by stamping the next day. 

I then go over the answers using the answer key.

The most common mistake by students is not having the correct oxidation numbers resulting in writing incorrect formulas is parts III and IV.  Also in part II many students forgot to put the roman numeral (II) for Cobalt (II) nitride.