# Periodic trends

17 Nov 2007

## Athletic Periodic Trends Review

Submitted by Lori Watson, Earlham College
Evaluation Methods:

Expert: The students get all periodic trends correct, can articulate all conflicting trends and make reasoned judgements as to which dominates, appreciate subtleties (size effects larger toward the left). Can articulate correct reasoning for their orderings even in complex situations. For example, can rationalize a diagonal trend.

Proficient: Students understand the primary periodic trends in isolation. Have some difficulty with conflicting trends. Subtleties essentially absent. Can articulate correct reasoning for their orderings in simple situations and inconsistently in complex situations. For example, can rationalize horizontal and vertical trends.

Apprentice: Students can arrange atoms/ions in primary trends correctly but do not articulate correct reasoning for their orderings. For example, trends may be memorized (size goes up as you go down).

Novice: Students can not consistently arrange atoms/ions in primary trends without coaching and cannot articulate correct reasoning for their orderings. For example, may know what happens to size as you go up and down but not left to right.

Evaluation Results:

Students generally do very well at ordering atoms according to "simple" trends (like atomic size).  Less familiar trends (polarizability, for example) or trends including ions (particularly mixed groups of atoms and ions) students seem to find more difficult.

Description:

­In this activity, students self-organize according to periodic trends. I print out the attached cards onto card stock (each page will contain two) and hand them out to the students (one to each). Generally, we go outside and I shout out periodic trends (i.e. size, polarizability, ionization energy, Zeff etc.) and the students run to get in line in the correct order.  I have a bell which I ding if correct, and a buzzer that I sound if incorrect. If incorrect, they have to try again. Students can "shout out" to their peers suggestions as to the ordering.  After the students are in the correct order (and sometimes when they are in the incorrect order if I see a consistent misconception in their thinking) I ask at least one student the reason for their chosen ordering. The "Instructor Notes" describe how I use this activity in General and Inorganic Chemistry and include a discussion of some common student misconceptions.

This activity typically takes about 10-15 minutes at the end of the lecture period in which we review periodic trends.  It can be easily modified for classes of different sizes by adding more atoms and ions.

Learning Goals:

A student should be able to apply his/her knowledge of periodic trends to participate in ordering a list of atoms and ions according to a given trend and should be able to explain the reasoning behind her/his choices.

Prerequisites:
Topics Covered:
Equipment needs:

The attached atom cards printed on card stock as well as a buzzer and a bell (or two other sound making devices).

Corequisites:
Course Level:
Implementation Notes:

The students really like this! Especially if they get to go outside (though running up and down the chemistry hallway is fun, too)!

Time Required:
15 minutes