« Return to AACT homepage

AACT Member-Only Content

You have to be an AACT member to access this content, but good news: anyone can join!

Need Help?

Introduction to Ionization Energy and Electronegativity with a Tactile Model Mark as Favorite (8 Favorites)

ACTIVITY in Periodic Table, Ionization Energy, Electronegativity. Last updated January 30, 2024.

Summary

In this activity, students will investigate the definitions of ionization energy and electronegativity as well as the periodic trends for each through building tactile models using Lego blocks.

Grade Level

High School

NGSS Alignment

This activity will help prepare your students to meet the performance expectations in the following standards:

  • HS-PS1-1: Use the periodic table as a model to predict the relative properties of elements based on the patterns of electrons in the outermost energy level of atoms.
  • Scientific and Engineering Practices:
    • Developing and Using Models
    • Analyzing and Interpreting Data
    • Engaging in Argument from Evidence

Objectives

By the end of this activity, students should be able to:

  • Define the terms ionization energy and electronegativity.
  • Identify periodic and group trends for ionization energy and electronegativity in the representative elements.
  • Apply the definition of ionization energy and electronegativity to different elements on the periodic table and explain why the trend differs between elements.
  • Differentiate between ionization energy and electronegativity.

Chemistry Topics

This activity supports students’ understanding of:

  • Periodic Table
  • Periodic Trends
  • Ionization Energy
  • Electronegativity

Time

Teacher Preparation: 15-20 minutes (needed the first time to sort the Lego bricks, but only 5 minutes for set up each time thereafter)
Lesson: 45-60 minutes

Materials

  • ~300 Lego bricks per group of 3-5 students
    • Do not use the flat Lego pieces, only the bricks of standard height
    • Lego bricks used do not need to be the same length
  • Paper copy of periodic table template on large 11” x 17” paper (preferred)
    • *Can be printed on two standard pieces of paper and taped together
  • Periodic Table

Safety

  • No specific safety precautions are needed for this activity.

Teacher Notes

  • This activity was designed as an inquiry-style introduction to electronegativity and ionization energy. Upon completion, students should have a fundamental understanding of both ionization energy and its periodic trend as well as electronegativity and its trend on the periodic table.
  • The author uses this activity as part of a 90-minute block. Typically, starting the class with a review of the atomic radius trends that students learned the day prior. Then, this activity about electronegativity and ionization energy is used before moving on to more traditional direct instruction so that students can use their knowledge from this activity to visualize the patterns as we discuss them.
  • It’s recommended to organize students in small groups of 3-5 for this activity.
  • Teachers could pair this activity with either of the Periodic Table Simulations from the AACT library:
  • Teachers could also add additional conclusion questions to challenge more advanced learners or have pre-constructed and labeled towers to place on the printed periodic table template to assist lower-level learners. This J. Chem. Ed. article discusses differentiation ideas, including using this technique for blind or visually impaired students.
  • To keep the activity from taking too much time, encourage groups of students to divide the elements when building the towers. Then, once all of the towers are built and placed, students can work individually or in cooperative groups to answer the questions, depending on what you find the most effective with your students.
  • Students should build each tower using a single color whenever possible. It makes the height comparison between towers much simpler and easier to see and understand.
  • The tower height values for Part 1 were adapted from ionization energy values in kJ/mol. For example, the ionization energy of hydrogen is 1312 kJ/mol which was converted into a tower height of 13 blocks. Slight adjustments were made for some specific elements like phosphorus for example. Its ionization energy value is 1012 kJ/mol which was converted into a tower value of 11 blocks instead of 10 in order to allow students to see that it has a larger value than sulfur.
  • The tower height values for Part 2 are loosely connected to Pauling values of electronegativity where 1 Pauling is equal to 5 blocks. Again, adjustments were made to individual values to allow for a simpler visualization of the trend.
  • An Answer Key document is available for teacher reference.

For the Student

Part 1: Ionization Energy

  1. What is an ion? You may use the Internet to help!
  2. Ionization energy is the amount of energy needed to make a neutral atom into an ion. Therefore, if you look at your answer to #1, ionization energy must be the amount of energy it takes to remove a(n) _____________________ from an atom.
  3. Sodium has an ionization energy of 496 kJ/mol and tends to form an ion with an overall charge of +1. Using that information combined with the periodic table, we can conclude that a sodium ion has 11 protons and requires 496 kJ/mol to form that ion that has 10 electrons. Complete the following chart showing what happens for lithium and potassium.
Name
Charge
 Ionization Energy Protons Electrons
Energy needed to become an ion
Lithium
+1
 520 kJ/mol
Potassium
+1
 418 kJ/mol
  1. Use the data table below to construct Lego towers that represent the ionization energy of each element listed. Then place each tower on the element’s correct location on the periodic table template.
    1. The “height of tower” numbers in the table below represents the number of bricks that should be placed vertically in the tower (the length of each of the bricks does not matter!)
    2. When building a tower for a specific element, you must use the same color bricks for the entire tower.
    3. You will build 26 towers.
Atomic Number
Element Symbol
Height of Tower
1
H
13
2
He
24
3
Li
5
4
Be
9
5
B
8
6
C
11
7
N
14
8
O
13
9
F
17
10
Ne
20
11
Na
5
12
Mg
7
13
Al
6
14
Si
8
15
P
11
16
S
10
17
Cl
13
18
Ar
15
19
K
4
20
Ca
6
31
Ga
6
32
Ge
8
33
As
10
34
Se
9
35
Br
11
36
Kr
14

Analysis

Use the towers to answer the following questions:

  1. The height of the towers represents the ionization energy of each element. Does ionization energy get higher or lower as you move down a group (from the top to the bottom) on the periodic table?
  2. Look at a full periodic table. Based on your answer to Question 5, circle the element from each pair that would have the HIGHER ionization energy:
    1. Fluorine or Bromine
    2. Arsenic or Phosphorus
    3. Rubidium or Lithium
  3. Does ionization energy get higher or lower as you move across a period (from the left to right) on the periodic table?
  4. Look at a full periodic table. Based on your answer to Question 7, circle the element from each pair that would have the HIGHER ionization energy:
    1. Fluorine or Carbon
    2. Arsenic or Bromine
    3. Iodine or Strontium
  5. Look again at the ionization energy as you move across a period from the left to right on the periodic table. If you look carefully, you should see that there are exceptions to the pattern you identified in Question 7. In Period 2, give an example of where that exception occurs.
  6. Let’s use an analogy: If I were holding a bag of Doritos that you wanted to take, ionization energy is how hard YOU have to work to get the Doritos. In chemistry, I am the atom, and the bag of Doritos is a valence electron. With this in mind, why is the ionization energy for calcium higher than bromine?

Part 2: Electronegativity

  1. Use the data table below to adjust the height of your Lego towers so that they instead represent the electronegativity value of each element listed instead of ionization energy.
    • The “height of tower” numbers in the table below represents the number of bricks that should be placed vertically in the tower (the length of each of the bricks does not matter!)
    • When building a tower for a specific element, you must use the same color bricks for the entire tower.
    • You will build 26 towers.
Atomic Number
Element Symbol
Previous Height
New Height of Tower
1
H
13
11
2
He
24
0
3
Li
5
6
4
Be
9
8
5
B
8
10
6
C
11
13
7
N
14
15
8
O
13
18
9
F
17
20
10
Ne
20
0
11
Na
5
5
12
Mg
7
6
13
Al
6
8
14
Si
8
9
15
P
11
11
16
S
10
13
17
Cl
13
15
18
Ar
15
0
19
K
4
4
20
Ca
6
5
31
Ga
6
7
32
Ge
8
8
33
As
10
10
34
Se
9
12
35
Br
11
14
36
Kr
14
0

Analysis

Use the towers to answer the following questions:

  1. The height of the towers represents the electronegativity of each element. Does electronegativity get higher or lower as you move down a group (from the top to the bottom) on the periodic table?
  2. Look at a full periodic table. Based on your answer to Question 2, circle the element from each pair that would have the LOWER electronegativity:
    1. Silicon or Carbon
    2. Chlorine or Bromine
    3. Magnesium or Strontium
  3. Does electronegativity get higher or lower as you move across a period (from the left to right) on the periodic table?
  4. Look at a full periodic table. Based on your answer to Question 2, circle the element from each pair that would have the LOWER electronegativity:
    1. Silicon or Sodium
    2. Chlorine or Silicon
    3. Magnesium or Aluminum
  5. Electronegativity is defined as how strongly an atom attracts electrons to itself when it is in a chemical bond. In other words, electronegativity is how tightly an atom holds on to its electrons when it reacts with something else. You may have noticed that there is a value of “0” indicated for 4 elements in the data chart. List the 4 elements that have a value of “0” listed for their tower height. Explain why they have this value.

Part 3: Conclusion

  1. Compare the trends for ionization energy and electronegativity (Part 1 questions 5 and 7, Part 2 questions 2 and 4). If we ignore the exceptions from Part 1, are the two trends the same or different?
  2. Let’s use an analogy: You and I are both holding a bag of Doritos. We both have our own strength and ability to pull the bag of Doritos to ourselves. Electronegativity is how tightly we are each holding on to the bag. In chemistry, we are both atoms in a bond and the Doritos are the electrons. With this in mind, when a bond forms between an oxygen atom and a hydrogen atom, which atom would pull the bag of Doritos (electrons!) closer to it?
  3. Keep thinking of that analogy and the trend you identified for electronegativity. If a bond forms between the following elements, circle the one that would pull the electrons closer to it.
    1. Nitrogen and Oxygen
    2. Nitrogen and Fluorine
    3. Nitrogen and Sodium