At a Glance


  • STEM
  • Chemistry

Instructional Level

  • College & CEGEP
  • University


  • Introductory Organic Chemistry II
  • Introductory Spectroscopy

Tasks in Workflow

Social Plane(s)

  • Group
  • Whole Class

Type of Tasks

  • Discussing
  • Solving problems
  • Analyzing

Technical Details

Useful Technologies

  • Smartboard, white boards

Class size

  • Medium (50-99)


  • Brief segment of class period (< 20 mins)

Instructional Purpose

  • Application & knowledge building
  • Consolidation & metacognition


In this exercise students briefly review concepts relating to chemical bonds prior to being introduced to the concept of the Index of Hydrogen Deficiency (IHD).

Working in small groups, the students are issued a molecular formula, for which they determine possible structures and calculate the IHD for their assigned formula and relate it to their structures.

Finally, IHD calculations are used analyze the possible structure of a more complex organic molecule.

Instructional Objectives

  • To review bonding in organic chemistry.
  • To be able to draw simple molecular structures with hydrogen, carbon, nitrogen, the halogens etc.
  • To learn the concept of hydrogen deficiency and how to calculate its index.
  • To apply IHD in the assessment of a molecule.

Workflow & Materials


Activity Workflow

View on CourseFlow

Contributor's Notes

Sebastien Robidoux

Sebastien Robidoux

Concordia University, Montreal

  • When done at the start of a course it serves to break the ice amongst students.
  • It encourages interaction between students.
  • There is not enough time to review the structures from every molecule.
  • With a large number of cards and several categories keeping the materials organized can be difficult.


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