Introduction to Crystal Structure: Bond Strength

Dexter Perkins
University of North Dakota
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  • This is an exercise to get students thinking about coordination number and bond strength
  • It is really an application of Pauling's Rules, mostly rule #2

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For use in an undergraduate mineralogy class.

Skills and concepts that students must have mastered

  • Students must know what ions and ionic bonding are
  • Students must know the meaning of "coordination number"
  • Students must have been exposed to Pauling's Rule #2 (the electrostatic valence principle)

How the activity is situated in the course

This is a group activity and is one of several activities that students do as they investigate the laws that govern atomic arrangement in crystal structures.


Content/concepts goals for this activity

  • It is one thing to talk in the abstract about ionic bond strength and another to do some exercises to help really comprehend
  • So, this exercise is intended to help students see how Pauling's second law applies to minerals structures

Higher order thinking skills goals for this activity

  • This exercise involves observation of fundamental chemical principles
  • This exercise involves analysis of fundamental chemical principles
  • This exercise involves application of fundamental chemical principles

Other skills goals for this activity

  • This exercise helps promote group activity
  • This exercise also promotes self-learning skills

Description of the activity/assignment

  • This exercise is designed to familiarize students with some basic crystal structures
  • The exercise helps students fully understand the nature and significance of ionic bonds and Pauling's second rule
  • It also builds a bit on Pauling's first rule (radius ratio principle)
  • It is one of several related activities, all of which are intended to help students understand the nature of ionic crystals

Determining whether students have met the goals

  • Students hand in their responses to the questions that are asked and so can be graded
  • Additionally, we ask related questions on exams at a later time

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