Notes:
The Electronegativity interactive is an adjustable-size file that displays nicely on tablets such as the iPad, on Chromebooks, and on laptops and desktops. It's use on phones is at best questionable. The size of the Interactive can be scaled to fit the device that it is displayed on. The compatibility with iPads, other tablets, and Chromebooks make it a perfect tool for use in a 1:1 classroom.
Teaching Ideas and Suggestions:
It is relatively easy to provide students a table of electrongegativity (EN) values and a couple of (somewhat arbitrary) cutoffs values (e.g., 0.5 and 1.8) between nonpolar covalent, polar covalent, and ionic bonds and have them classify bond types. It is quite another task to assist them in an understanding of the nature of the bond. We believe the world of bonding is a bit murkier than the usual classifying pratice. The fact is that a bond like Ca-S, which often falls on the covalent side of many cutoff marks, probably has much more in common with the Na-Cl bond than it does with the N-O bond. If ...
- your inner teacher is a bit troubled by the pretension that bond classification is as clear (and as important) a task as any task;
- you're a believer in the idea that bonds lie along a spectrum and not just inside of boxes labeled Nonpolar Covalent, Polar Covalent, and Ionic;
- you would like students to understand more about bonds than the class it falls into;
... then we think we have the tool that you have been looking for.
Our Electronegativity simulation is equipped with a number of features that support students in navigating the murky waters of bond formation. Students will select two elements from among the first 20 elements of the Periodic Table. An electron shell diagram of each element is constructed. One valence shell electron from each atom is then donated to the bond. Students watch as the two atoms exert attractive forces on the two electrons. The atom with the greatest electronegativity value pulls the electrons closer to its nucleus. Students can view a report of the electronegativity values and the percent ionic and covalent character of the bond. A slider is placed along a spectrum to show the degree of sharing/transfer that the bond exhibits. And a dipole moment vector is drawn in the sim window with positive and negative centers of charge indicated near the vector arrow.
Students can select any two elements that they wish from among elements #1-20. The three noble gases are not be involved in bonding. Two metals can be selected. Their bond type is displayed as metallic bonding and the valence electrons are shown roming freely in the electron sea (at least as best as we could show it). The sim displays a
van Arkel-Ketelaar Triangle with a dot locating the general location of the bond on the 3D spectrum of bond types. Students can easily toggle back and forth between the triangle display and the percent ionic/covalent display (except when viewing a metallic bond).
Classrooms can simply open the Interactive and explore the ideas. Or if desired, The Physics Classroom has prepared a student activity sheet for a more directed experience. The focus of the activity is on evaluating a few commonly used models regarding bond types ... some of which most of us use. Each model is evaluated in terms of their strengths and weaknesses and will make for some good class discussions on bond classifications. The first two models are likely familiar to most teachers. The third model - the
van Arkel-Ketelaar Triangle - is less familiar and will require some explaining to students. We have included the third model on the fifth page of the five-page handout. Those teachers who would like to skip this third model can easily do so by not including the fifth page. View
Activity Sheet.
Our Electronegativity simulation will soon be available with a
Concept Checker that coordinates closely with out
Activity Sheet. Do the simulation with the help of the Activity Sheet. Then follow it up with the
Concept Checker. Student progress is saved for classrooms with a Task Tracker subscription.
Related Resources
You will find numerous activities and resources on our website that would complement this activity. Here are a few you may be interested in:
Chemistry Tutorial: Chemical Bonding Chapter, Lesson 1a
Our Tutorial page on
Types of Bonds is a great complement to this exercise.
Concept Builder:
Bond Polarity
Our Bond Polarity Concept Builder is a great follow-up to this activity. It includes three scaffolded activities that interactively lead the student to understand of the polarity of a bond. Students use electronegativity values (provided) to identify a bond as being polar or nonpolar. If polar, the learner must identify the direction of the dipole moment vector. There are three difficulty levels that differ only in terms of the number of questions delivered to the learners. There are a total of 27 questions organized into 9 different Question Groups and spread across the three activities. Question-specific help is provided for each of the 9 situations. Questions in the same Question Group are similar questions. Student progress is tracked and saved for Task Tracker classes.
Science Reasoning Center:
The Periodic Table, Elements and Their Bonds
Our interactive
The Periodic Table, Elements and Their Bonds science reasoning activity is also a great follow-up to our Electronegativity simulation. It includes four scaffolded activities that begin with an investigation of the substructure of atoms and ions. The activity focuses on the relationship between the location of an element on the Periodic Table and its tendency to form an ionic, covalent, or metallic bond with other elements on the table. The activity addresses the HS-PS1-1 Performance Expectation of the Next Generation Science Standards.
Credits