Student Activity Kit
Materials Included In Kit
“Periodic Placement of the Elements” handout master
Plotting Trends Worksheet master
Reaction plates, 96-well, 6
“Representative Element Data” handout master
Straws, package of 500
Additional Materials Required
Index card, 4" x 6"
Metric rulers, 30 cm
Plumber’s putty (optional)
- Form a working group as directed by your teacher and obtain all of the necessary materials, including the Plotting Trends Worksheet and two handouts, “Representative Element Data” and “Periodic Placement of the Elements.”
- The “Representative Element Data” handout lists the properties of the first 34 members of the representative or main group elements (Groups IA–VIIIA). The transition metals are not included in the list.
- Your teacher will assign each group one physical property to study.
- In the calculations that follow, one cm is first subtracted from the maximum straw length (step 4) to determine a “straw scale” ratio. This is then added back on to determine the cut straw length for each element (step 7). One centimeter is the depth of the wells on the reaction plate.
- Make enough copies of the Plotting Trends Worksheet and the Representative Element Data and Periodic Placement of the Elements handouts to give all students individual copies. Two 50-minute class periods will likely be needed to complete this activity. The activity may be completed in one class period if the “straw length” calculations are assigned as homework.
- This kit contains enough materials for a class of 24 students working in groups of four (six student groups). Six physical properties of the elements are listed on the Representative Element Data handout. This makes it possible to assign each group of four in a class of 24 students a unique physical property to study. All physical properties on the handout will be accounted for and there will be no duplications. For smaller or larger class sizes, adjust the sizes of the working groups and discard or double up on the assigned physical properties, as needed.
- The Representative Element Data handout lists the physical properties of 34 representative (main group) elements—Groups IA–VIIIA and periods 1–5 in the periodic table. The transition elements are not included. Notice the gaps on the handout for atomic numbers 21–30 and 39–48.
- This is best performed as a cooperative group activity. Monitor or assess student interaction to assure that students share responsibilities and decisions. It may be helpful to suggest that one student in each group take on the role of checking all calculations.
- Review beforehand or assign as prelab preparation the definitions and units of the physical properties.
- Set aside a common area for students to display their charts and the accompanying descriptive index cards. Students may report on their investigation and lead a discussion of possible explanations for the observed periodic trend.
- The reaction plates and handout masters are reusable from year to year. Save all materials for future use. The only consumable items that must be resupplied are straws!
- See the Sample Data section for an illustration of a possible “straw chart” and an explanation of the observed periodic trend in the ionization energies of the elements.
Correlation to Next Generation Science Standards (NGSS)†
Science & Engineering Practices
Developing and using models
Planning and carrying out investigations
Analyzing and interpreting data
Disciplinary Core Ideas
MS-PS1.A: Structure and Properties of Matter
HS-PS1.A: Structure and Properties of Matter
Systems and system models
Scale, proportion, and quantity
Definition: Energy needed to remove one of the electrons from an atom (specifically, from an isolated atom in the gas phase). The energy needed to remove successive electrons is called the first ionization energy, second ionization energy, etc. Units are kilojoules per mole (kJ/mole).
Periodic Trend: Ionization energy increases going up a column and from left to right in the periodic table. Thus, among the naturally occurring, representative (main group) elements, helium has the highest ionization energy and cesium the lowest. Note: There is a slight dip in the ionization energy between the Group IIA and IIIA elements as one proceeds from left to right across any period in the periodic table (see Figure 2).
Explanation: Ionization energy decreases as the period number increases because electrons are held less strongly the further out they are from the nucleus. Recall that the period number for any element in the periodic table corresponds to the value of the principal energy level for its outermost electrons. The distance from the nucleus increases as the value of the principal energy level increases. Ionization energy increases from left to right across the periodic table because the effective nuclear charge (number of protons) of an atom increases in this direction, while the approximate distance of the electrons from the nucleus remains the same. Thus the electrons are held more strongly and require more energy to remove. The apparent “zig-zag” pattern in the ionization energies of the Group IIA and Group IIIA elements is due to the difference in energy between the ns and np orbitals. The p-orbitals are slightly higher in energy than the s-orbital and the p-electrons are thus easier to remove.