3.1: Question 3.E.05 PASS - ranking first ionization energy
- Page ID
- 452275
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)
Based on their positions in the periodic table, rank the following atoms in order of increasing first ionization energy: F, Li, N, Rb
- Answer
-
Rb, Li, N, F
See LibreText 3.2 Periodic Variations in Elemental Properties
- Strategy Map
-
Step Hint 1. Map out the order of the requested list See LibreText 3.2 Periodic Variations in Elemental Properties
Order the given elements by the amount of energy it would require removing their most loosely bound electron.
- lowest/smallest to highest/greatest first ionization energy
It must be ordered by the element that would require the least amount of energy to the element that would require the most.
- less than < greater than
2. Recall the definition of ionization energy, what process does it describe? Refer to LibreText Section 3.2.4: Variation in Ionization Energies
3. Summarize the trend in the periodic table
Ionization Energies: The ionization energies increase from left to right, and decrease from top to bottom. 5. Find the elements on the periodic table and arrange them based on the trend of increasing ionization energies. 
- Solution
-
The locations of F, Li, N, Rb on the periodic table:
- F, atomic number 9, period 2, group 17
- Li, atomic number 3, period 2, group 1
- N, atomic number 7, period 2, group 15
- Rb, atomic number 37, period 5, group 1
List smallest to largest first ionization energy: Rb < Li < N < F
Answer
In order of increasing first ionization energy: Rb, Li, N, F
- Guided Solution
-
Guided Solution Hint This problem requires understanding of theory behind periodic trends
Based on their positions in the periodic table, rank the following atoms in order of increasing first ionization energy: F, Li, N, Rb
See LibreText 3.2 Periodic Variations in Elemental Properties This question asks us to rank the given elements by their ionization energies. First ionization energy is "the amount of energy required to remove the most loosely bound electron from a gaseous atom in its ground state"
Recall: "Energy is always required to remove electrons from atoms or ions, so ionization processes are endothermic and IE values are always positive."
Consider what characteristics may influence the amount of energy required to remove an electron from an atom
- Effective Nuclear Charge (Zeff)
- Atomic Radius
Recall that an electron is negatively charged, and the nucleus is positively charged.
Consider what factors impact the strength of attractive (Coulombic) forces from the nucleus that are felt by the valence electron
Refer to LibreText Section 3.2.1: Effective Nuclear Charge: Penetration and Shielding
Refer to LibreText Section 3.2.2: Variation in Covalent Radius3.2: Periodic Variations in Element Properties
How does Zeff and atomic radius vary across the Periodic Table?
Which characteristic is most influential on ionization energy?
Effective Nuclear Charge (Zeff): The effective nuclear charge increases from left to right and increases from top to bottom on the periodic table.
Atomic Radius: The atomic radius decreases from left to right, and increases from top to bottom
- Atomic radius has more impact on first ionization energy than effective nuclear charge
How does first ionization energy vary across the Periodic Table? Ionization Energies: The ionization energies increase from left to right, and decrease from top to bottom.
- As atomic radius increases, first ionization energy decreases (less energy is required to remove the outer-most electron)
- the smaller the atomic radius, the larger the first ionization energy (the more energy required to remove the outer-most electron)
Locate the elements on the Periodic Table
- F (fluorine), atomic number 9, period 2, group 17
- Li (lithium), atomic number 3, period 2, group 1
- N (nitrogen), atomic number 7, period 2, group 15
- Rb (rubidium), atomic number 37, period 5, group 1
List the elements in order of largest to smallest atomic radii
Rb, Li, N, F
- (largest) Rb; due to principal quantum number n=5 > n=2
- Li > N > F (smallest); due to increasing effective nuclear charge (Zeff) moving left to right across the periodic table
List smallest to largest first ionization energy:
Rb, Li, N, F
smallest first ionization energy: Rb < Li < N < F largest first ionization energy
Does this make chemical sense? It is easiest to remove rubidium's valence electron because it is furthest from the nucleus and is held by the weakest attractive forces; it is hardest to remove fluorine's valence electron because it is closest to the nucleus and held by the strongest attractive forces (question source 6.5.5 from 6.E: Electronic Structure and Periodic Properties (Exercises): https://chem.libretexts.org/Bookshelves/General_Chemistry/Chemistry_1e_(OpenSTAX)/06%3A_Electronic_Structure_and_Periodic_Properties_of_Elements/6.E%3A_Electronic_Structure_and_Periodic_Properties_(Exercises), shared under a CC BY 4.0 license, authored, remixed, and/or curated by OpenStax, original source question 71 https://openstax.org/books/chemistry-2e/pages/6-exercises, Access for free at https://openstax.org/books/chemistry/pages/1-introduction)