In every issue of The Science Reflector look for this new section including activities you can use in your classroom tomorrow. If you have activities you would like to share please email the editor.

Isotopes of Candium - use candy to measure the average atomic mass of an element

Creek Study - explore the health of a local creek using observations and measurements of chemical and biological water quality factors.

Isotopes of Candium
from Dennis Jonhson (with input from Scott Grumelot and Anuranjan Shand)
The Science House

Isotopes of atoms occur when an atom of the same type contains fewer or more neutrons in its nucleus. These atoms exhibit the same chemical and physical properties. The average atomic mass of an atom is an expression of these differences in the number of neutrons in the nucleus of an atom. This simulation provides a simple experiment for calculating the average atomic mass of an element.

Materials

M&M candy pieces
Skittles candy pieces
Reece’s Pieces candy pieces

Procedure

1. Remove the atoms of Candium from the cup.
2. Determine the average mass of a single atom of a Candium. (mass of Candium atoms/ number of Candium atoms).
3. Examine the Candium atoms noting any differences.
4. Sort the Candium atoms into groups based on the presence or absence of markings. Record each group in the data table.
5. Determine the average mass of one atom for each Candium isotope type. Record your results in the data table.
6. Determine the percent by number of each isotope in nature. Record this in the data table.
7. Multiply the mass of one atom (a) by the percent in nature (b). Record this in column c.
8. Determine and record the average atomic mass of Candium by adding the values in column “c”.

Data Table:

Questions:

1. In this experiment, what is the average atomic mass of Candium?
2. What is the arithmetic average for all of the Candium atoms? (Step 2)
3. Compare the arithmetic average for Candium and the Average Atomic Mass.
   Should these numbers be the same? Explain your answer.
4. Define, in your own words, what an isotope is.
5. Compare your answers with other groups. How do your answers compare.
   Discuss and record any differences or similarities.

Teacher Notes:

An isotope is an atom that has a different number of neutrons in its nucleus but the same number of electrons and protons. The atoms are identical in their physical and chemical properties but have slightly different masses. This is due to the different number of neutrons in the nucleus of the atoms.

Calculation instructions

1. To determine the average mass of one atom of the isotope (column a), determine the mass of all of the candies of the same type and divide by the number of candies of that type.

2. To determine the percent of the isotope in nature (column b), divide the total pieces of the isotope by the total number of Candium atoms (candy pieces).

3. To determine the percent mass of each isotope, multiply column “a” by column “b”. This answer gets recorded in column “c”

4. To determine the Average Atomic Mass of Candium, add the numbers in column “c”. This represents the average mass of all of the isotopes of Candium.

The three different isotopes of Candium in this experiment are M&M’s, Skittles, and Reece’s Pieces candies. When preparing each set of candies be sure to include the same number of each candy in each cup so comparisons between lab groups can be made. For more advanced groups vary quantities of each candy in the cups. Students can then compare their samples and determine the class Average Atomic Mass based on a larger sample size.

Creek Study
from Linda Walker
Science Teacher at Cane Creek Middle School, Buncombe County
2006 Outstanding Science Teachers, District 8

Editor's Note:
Below are materials that Linda uses with her students to explore Cane Creek, which runs behind the school. They can easily be adapted for any creek or stream. The rubrics and data sheets have been refined over many years of performing creek studies. Linda would love to hear from anyone with any improvements, enhancements or corrections - linda.walker@bcsemail.org.

Objective:
As we study Cane Creek, you will be making visual, chemical, biological, and physical observations. Research will be completed regarding the watershed’s natural and human interactions with the creek. The information you gather will then be generated into a report.

Scenario:
You have been asked to implement a scientific study of Cane Creek, you will be writing a report to a local North Carolina legislative delegate. This report was requested to determine if any further legislation is warranted for maintaining Cane Creek’s healthy role in the community.

Cross Curricular Guidelines:

Data Collection:
Several chemical tests will be conducted on the water: pH, nitrate levels, ammonia levels, and dissolved oxygen. Using a kick net, an attempt will be made to get a population estimate and identification of the aquatic insects found in the stream. Finally, we will be gathering general information regarding Cane Creek including, but not limited to: water temperature, stream depth, flow speed, vegetation, stream bed conditions, and water color & smell. These physical attributes will be logged on a Stream Survey form.

Community Awareness:
A map will be drawn of the Creek’s movement through the campus of Cane Creek Middle and how natural and human interactions impact it’s health. You will determine which watersheds this water continues to flow through, prior to reaching the ocean. You will research key legislative efforts made to safe guard waterways.

Statistical Analysis:
The data gathered will be plotted and analyzed. A spreadsheet will be prepared to generate the graphs, one of which will later be imported into your presentation. All computations will be maintained within the report folder for future verification. Students will be required to create a pictorial graph of the life forms found in each category, a concurrent graph of temperature, pH, and dissolved oxygen as the numbers change over the day. An analysis of these relationships will be examined.

Communication Skills:
Upon completion of the initial draft of the report, students will assemble in peer pairs to evaluate each other’s report to confirm information is presented in a clear manner, all information requested is present, and to verify the grammar is cohesive.

Final Report Components:

Each report should include, but not be limited to the following:

• Where is Cane Creek located? What other waterways does the water flowing from Cane Creek impact? Which major body of water does Cane Creeks effluents finally reach?
• What is the health status of the river according to the chemical test results? Discuss what each reading means about the creek. Insert a graph explaining the relationship between the temperature readings taken over time.
• What is the condition of the river according to the bug survey? Discuss the kinds of bugs found and what they indicate. Insert pictorial information indicating the types bugs populating the creek.
• What interacts with the river – plant life, animal life, and human activity? Include in this section the path the water must travel prior to getting to the creek bed. Discuss watersheds. Discuss the give and take relationship between humans and the creek – keywords in this section would include flooding and pollution
• What are the physical attributes of the river – size (width & depth), water appearance, streambed condition, flow direction, and other general notes made?
• Discuss the effects of present legislative policies – are they enforced, effective, and environmentally practical?

Data Collection Stations

At the Observation Station, the stream flow will be ascertain initially by determing the direction of the sun and time of day. Confirmation of this data will be done using a compass. This station will also do stream flow calculations by sectioning off 3 meters length and timing a basketball as it travels this distance. Measurements of width and depth will be done. Observations from a previous visit will be reevaluated: steam color, riparian vegetation, creek odor, streambed conditions, and animal life evidence.

At the Probe Station, temperature, turbidity and pH data will be collected. Students will use the lab pro and calculators to collect this information. Students will also use a manual thermometer and a turbidity tube to cross check and verify the data collected. Students can continue to reevaluate previously acquired data: steam color, riparian vegetation, creek odor, streambed conditions, and animal life evidence.

At the Bug Station, kicknets and magnifying glasses will be the predominant equipment used. Any bugs found will be placed in a container while viewing them and using the charts. Repect will be paid to this organisms and all animals will be returned to the creek with as little handling as possible. Once again further confirmation of any previous observations should be noted, particularly for steam color, riparian vegetation, creek odor, streambed conditions, and animal life evidence.

Support Documents (in PDF format)

• Assessment Rubric
• Student Data Sheet
• Chemical Analysis Notes