This is a handout which I use in an advanced general chemistry course, but which could be used in an inorganic course as well. It is a mini-periodic table with common cations and their charge to size ratios expressed as Q/r², where Q is in integer charges (+1, +2), and r is in Angstroms. Conveniently, Na⁺ is an easy to remember 1.0, and Al³⁺ and Be²⁺ are easy to remember values of 10. This corresponds to the polarizing power of these ions, and is a crude proxy for how covalent their interactions with a given anion tend to be.

This is an interactive Challenge in which students have to find others in the room with whom they "match" as a hard or soft acid or base. It brings to life the way inorganic chemists think about HSAB. Inorganic Challenges are exercises designed to be solved by a small group of students. Some Challenges practice a problem-solving algorithm, some reinforce important concepts, and some involve creativity or games.

This is a Challenge for the beginning of an Inorganic class, to remind students of the basics of Aufbau, etc. Inorganic Challenges are exercises designed to be solved by a small group of students. Some Challenges practice a problem-solving algorithm, some reinforce important concepts, and some involve creativity or games. You can pick and choose Challenges from our Web site to increase active learning in your classroom, and we ask that you contribute creative Challenges of your own to give a head start to teachers at other colleges and universities!

This is a beginning-of-semester "warm up." The goals are to help students reconnect to their prior knowledge about atomic orbitals and to introduce and practice the fundamentals of good small group work.