Periodic Relationships Between the Elements: Ranking First Ionization Energy
Question
Based on their positions in the periodic table, rank the following atoms in order of increasing first ionization energy: F, Li, N, Rb.
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Rb < Li < N < F
Refer to Section 3.2: Periodic Variations in Element Properties (1).
Strategy Map
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| Strategy Map Steps |
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| 1. Identify if your list should ascend or descend. |
2. What is ionization energy? Identify what elemental property it relates to.
Show/Hide HintThink about which elements are more likely to readily donate electrons and which elements are more likely to want to hold onto their electrons. |
Solution
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- F — atomic number 9, group 17, period 2
- Li — atomic number 3, group 1, period 2
- N — atomic number 7, group 15, period 2
- Rb — atomic number 37, group 1, period 5
Rubidium is the most likely to easily give up a valence electron, whereas fluorine is the least likely to easily give up a valance electron.
Answer: Rb < Li < N < F
Guided Solution
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The guided solution below will give you the reasoning for each step to get your answer, with reminders and hints.
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| Guided Solution Ideas |
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This question is a theory type problem where you must order the given elements by the amount of energy it would require to remove their most loosely bound electron. It must be ordered by the element that would require the least amount of energy to the element that would require the most.
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This question asks us to rank the given elements by their ionization energies.
Think Don’t Forget!We can do this by applying out knowledge of the ionization energy trends. Think Don’t Forget!Recall that ionization energies increase from left to right and decrease from top to bottom. Refer to 3.2.1.4: Periodic Trends Due to Penetration and Shielding in Section 3.2: Periodic Variations in Element Properties (1). |
How does the position of an element on the periodic table help predict its size or ionization energy (in general)?
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| Complete Solution |
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The atoms who have the highest first ionization energy are those who have the least number of shells and are least affected by shielding and high electronegative. Following the trend pattern, first ionization energy will increase from bottom to top and from left to right on the periodic table. Rubidium is the most likely to easily give up a valence electron, whereas fluorine is the least likely to easily give up a valance electron. Answer: Rb < Li < N < F |
Check Your Work
Summary of what we would expect based on the related chemistry theory.
Does your answer make chemical sense?
Show/Hide Answer
Ionization energy is the amount of energy it takes to remove the most loosely bound electron from an atom.
The larger the atom, the further that electron is from the nucleus. This means it is under less nuclear pull by the nucleus and will require less energy to pull away from the atom completely. An electron from a small, tightly bound atom such as fluorine would require much more energy to remove than a large loosely bound atom such as francium.
PASS Attribution
- LibreTexts PASS Chemistry Book CHEM 1500 (2).
- Question 3.E.5 from LibreTexts PASS Chemistry Book CHEM 1500 (3) is used under a CC BY-NC-SA 4.0 license.
- Question 3.E.5 was adapted from question 6.5.5 from LibreTexts Chemistry 1e (OpenSTAX) (4), which is under a CC BY 4.0 license.
- Question 6.5.5 is question 71 from OpenStax Chemistry 2e (5), which is under a CC BY 4.0 license. Access for free at https://openstax.org/books/chemistry-2e/pages/1-introduction.
References
1. LibreTexts. 3.2: Periodic Variations in Element Properties. In CHEM1500: Chemical Bonding and Organic Chemistry. LibreTexts, 2023. https://chem.libretexts.org/Courses/Thompson_Rivers_University/CHEM1500%3A_Chemical_Bonding_and_Organic_Chemistry/02%3A_Quantum_Theory_and_Electronic_Structure_of_Atoms/2.02%3A_Atomic_Spectroscopy_and_The_Bohr_Model.
2. Blackstock, L.; Brewer, S.; Jensen, A. PASS Chemistry Book CHEM 1500; LibreTexts, 2023. https://chem.libretexts.org/Courses/Thompson_Rivers_University/PASS_Chemistry_Book_CHEM_1510%2F%2F1520.
3. Blackstock, L.; Brewer, S.; Jensen, A. 3.1: Question 3.E.05 PASS – ranking first ionization energy. In PASS Chemistry Book CHEM 1500; LibreTexts, 2023. https://chem.libretexts.org/Courses/Thompson_Rivers_University/PASS_Chemistry_Book_CHEM_1500/03%3A_Periodic_Relationships_Among_the_Elements/3.01%3A_Question_3.E.05_PASS_-_ranking_first_ionization_energy.
4. OpenStax. 6.E: Electronic Structure and Periodic Properties (Exercises). In Chemistry 1e (OpenSTAX). LibreTexts, 2023. https://chem.libretexts.org/Bookshelves/General_Chemistry/Chemistry_1e_(OpenSTAX)/06%3A_Electronic_Structure_and_Periodic_Properties/6.E%3A_Electronic_Structure_and_Periodic_Properties_(Exercises).
5. Flowers, P.; Robinson, W. R.; Langley, R.; Theopold, K. Ch. 6 Exercises. In Chemistry 2e; OpenStax, 2019. https://openstax.org/books/chemistry-2e/pages/6-exercises.
