Groups and Periodic Trends
Groups and Families or Just a Common Location?
Introduction
Scientists often refer to the vertical columns of the periodic table as groups or families such as the Halogens, Chalcogens, Alkaline Earth Metals, etc. It is up to you (and your team) to agree or disagree with this commonly accepted designation. Are these groups of elements so deserving of such a personal title? You will support your conclusion with research to provide concrete evidence for your perspective on this issue.
The Task
Groups of three or four people will form a Web Quest Team. The Team will choose a vertical column of elements in the periodic table, research the individual elements and then view the properties of each species relative to the others in the group. Each member of the Team must be responsible for at least one element within the vertical column of elements, and all of the elements within the selected column of elements must be compared. Through similarities and differences, each individual will present an argument for the acceptance or rejection of the title family to the other members of the Web Quest Team. In addition to research focused directly upon the elements of a chosen group, teams may research elements in adjacent columns as supporting evidence for their theories.
For each element in the group a one page summary should be prepared by individual Team members. Items to include in the summary:
- Date of Discovery
- Name of discoverer(s)
- Nationality of the discoverer(s)
- Melting Point, Boiling Point, Density, Size (or atomic radius), Electronegativity
- Properties of the element (oxidation numbers, reactivity, etc.)
- Occurrence in nature
- Source of element name (example: Vanadium was named after a Norse Goddess)
- Toxicity to humans? (LD-50, etc.)
- Uses of the Element in society
- Isotopes and half-lives (if relevant)
- ...anything else of interest or relevance?...
Resources
These sites represent a small fraction of the web resources available on the Internet, but they might be a good starting point for your research.
Web Elements
This site will prove to be an invaluable stepping stone for your research. Use the program to provide the basic properties of each element in the group you have chosen and generate further questions to continue research at other sites.
The Photographic Periodic Table of the Elements
Pictures of each element and some uses are provided. Very cool site related to the "Elements" iOS app.
Chemical Database
Enter a name, a formula, a molecular weight, or a CAS RN, and substructure. This searchable chemical database will provide information on both the elements and the compounds they form. 150 chemical information sites are indexed through this site.
NASA STI Compliance and Distribution Services
Search here for details not found under a more general search. This site will help some groups to locate uses of particular elements.
The Process
- Form a Web Quest Team with between two and four members
- Choose a vertical column on the periodic table; ideally it will fit your group size. If not, some members may have more than one element to research
- Use the resources provided above to begin researching the properties and history of the elements in your column. Write a one page summary of your element. Be sure to include the information listed above under "The Task" for each element.
- Reassemble the Team and compare the periodic properties of the elements. Do the trends agree? If so, write a joint conclusion report stating the trends that follow a linear progression - this is truly a "family" of elements. If not all Team members agree with the family status, include a Dissension statement by the minority explaining the reason for the controversy (i.e. why this group should not be a family.)
- Include an abstract and introduction statement with your paper.
- Also be sure to include a list of references showing the source of your information.
Conclusion
Information concerning the elements of the periodic table and the compounds they form is virtually limitless. Many scientists, teachers and students have put a considerable amount of time into creating sites which simplify the process of finding this information. You should feel comfortable with the process of searching for information on a particular element. After working with your group, the study of the relative properties of elements within a particular group should also pose no problem. The information is out there! Keep searching and the resources to find your information will come to you!
Evaluation
Each Web Quest Team member can receive a maximum of 5 extra credit points for completing this Web Quest. Three points shall address the perspective statement created by each individual Team member, and two points shall address the group work used to complete the paper.
Grading shall be based on neatness, spelling errors, accuracy of information gathered, quality of list of references, and similar criteria. In addition, each participant shall anonymously complete an evaluation form for each Team member which will affect the final grade. For more information, contact the instructor.
WebQuest originally developed by Colleen Campbell at Miller Place High School in Miller Place, New York, USA, and adopted as appropriate by Michael Russell at Mt. Hood Community College in Gresham, Oregon, USA