Ch.8 - Periodic Properties of the ElementsSee all chapters
All Chapters
Ch.1 - Intro to General Chemistry
Ch.2 - Atoms & Elements
Ch.3 - Chemical Reactions
BONUS: Lab Techniques and Procedures
BONUS: Mathematical Operations and Functions
Ch.4 - Chemical Quantities & Aqueous Reactions
Ch.5 - Gases
Ch.6 - Thermochemistry
Ch.7 - Quantum Mechanics
Ch.8 - Periodic Properties of the Elements
Ch.9 - Bonding & Molecular Structure
Ch.10 - Molecular Shapes & Valence Bond Theory
Ch.11 - Liquids, Solids & Intermolecular Forces
Ch.12 - Solutions
Ch.13 - Chemical Kinetics
Ch.14 - Chemical Equilibrium
Ch.15 - Acid and Base Equilibrium
Ch.16 - Aqueous Equilibrium
Ch. 17 - Chemical Thermodynamics
Ch.18 - Electrochemistry
Ch.19 - Nuclear Chemistry
Ch.20 - Organic Chemistry
Ch.22 - Chemistry of the Nonmetals
Ch.23 - Transition Metals and Coordination Compounds
Trends in Ionic Radius

Concept #1: Understanding ionic radius

Example #1: Rank each set of ions in order of increasing ionic size. 

a)  K+ , Ca2+, Ar

b)  Sr2+, Na+, I 

c)   V5+, S2-, Cl 

Additional Problems
For an isoelectronic series of ions, the ion that is the smallest is always 1. the ion with the fewest protons. 2. the least positively (or most negatively) charged ion. 3. the ion with the highest atomic number. 4. the ion with the most neutrons. 5. the ion with the most electrons.
List the following ions in order of increasing radius: Na+, O 2−, Mg 2+, F −, Al 3+. A) O 2− > Mg 2+ > F − > Na+ > Al 3+ B) Na+ < Mg 2+ < Al 3+ < O 2− < F − C) O 2− < F − < Na+ < Mg 2+ < Al 3+ D) Al 3+ < Mg 2+ < Na+ < F − < O 2− E) Na+ < Mg 2+ < Al 3+ < F − < O 2−
Which ion below has the greatest radius? A. Li+  B. Na+  C. S2- D. Cl- E. Ca2+
Which ion has the largest radius? A) Cl- B) Kr+ C) Br - D) F- E) Na+
Which ion in the isoelectronic series below has the smallest radius in a crystal? A) O2- B) N3- C) Na+ D) Al3+ E) F -
Which isoelectronic ion is the  smallest ? a) Al3+ b) Na+ c) F- d) O2-
Which ion has the largest radius? a) Cl - b) F - c) K+ d) Cu2+
Which of the ions listed below would be the smallest? (a) Cl − (b) S 2− (c) K + (d) Ca 2+ (e) They will all be the same size.
Which of the following is an isoelectronic series listed with decreasing radius? a. Se2- > Br – > Kr b. Cl – > Br – > I – c. Ca2+ > Sr 2+ > Ba2+ d. Ca2+ > K + > Ar
Rank each set of ions in order of increasing ionic size. Cr7+, Sc3+, P3–, Cl–
You may want to reference (Pages 357 - 365) section 8.7 while completing this problem.Arrange this isoelectronic series in order of increasing radius: Se2-, As3-, Rb+, and Br-.
You may want to reference (Pages 262 - 267)Section 7.3 while completing this problem.Put the following atoms and ions in order of increasing ionic radius: F, S2-, Cl, and Se2-.
Which neutral atom is isoelectronic with each of the following ions: Ga3+, Zr4+, Mn7+, I-, Pb2+?
The ionic substance strontium oxide, SrO, forms from the direct reaction of strontium metal with molecular oxygen. The arrangement of the ions in solid SrO is analogous to that in solid NaCl and is shown here. Based on the ionic radii r(O2-) = 1.40 Å and r(Sr2+) = 1.13 Å, predict the length of the side of the cube in the figure.
You may want to reference (Pages 268 - 272) Section 7.4 while completing this problem. Enter equations that show the following processes.The fourth ionization energy of zirconium.
You may want to reference(Pages 263 - 267) Section 7.3 while completing this problem.In a lithium ion battery that is discharging to power a device, for every Li+ that inserts into the lithium cobalt oxide electrode, a Co4+ ion must be reduced to a Co3+ ion in order to balance the charge. Using the CRC Handbook of Chemistry and Physics or other standard reference, find the ionic radii of Li+, Co3+, and Co4+. Order these ions from largest to smallest.
Provide a brief explanation for each of the following.S2 - is larger than O2 - .
In the ionic compounds LiF, NaCl, KBr, and RbI, the measured cation-anion distances are 2.01 Å (Li - F), 2.82 Å (Na - Cl), 3.30 Å (K - Br), and 3.67 Å (Rb - I), respectively. Predict the cation-anion distance using the values of ionic radii given in the figure.
In the ionic compounds LiF, NaCl, KBr, and RbI, the measured cation-anion distances are 2.01 Å (Li - F), 2.82 Å (Na - Cl), 3.30 Å (K - Br), and 3.67 Å (Rb - I), respectively. Calculate the difference between the experimentally measured ion–ion distances and the ones predicted from the figure.
Consider S, Cl, and K and their most common ions.Explain any differences in the orders of the atomic and ionic sizes.
Cation and anion size. Radii, in angstroms, of atoms and their ions for five groups of representative elements.How do cations of the same charge change in radius as you move down a column in the periodic table?
The following ions contain the same number of electrons. Rank them in order of decreasing ionic radii.Cs+, I -, La3+, Sb3-, Ba2+, Te2-
Arrange the following ions in order of increasing ionic radius: Br -, Te 2-, I -a. I- < Te2- < Br-b. Te2- < Br- < I-c. Br- < I-  < Te2-d. Br- < Te2- < I-e. Te2- < I- < Br-
Rank these ions according to ionic radius from largest to smallest: Na+, Mg 2+, N 3-, O 2-, F-
Place the following ions in order from smallest to largest ionic radii: Note that < means less than. K + , Ca 2+ , S 2- , and Cl - . a. S 2- < Cl - < Ca 2+ < K + b. Ca 2+ < K + < Cl - < S 2- c. S 2- < Cl - < K + < Ca 2+ d. K + < Cl - < S 2- < Ca 2+ e. Ca 2+ < K + < S 2- < Cl -
Rank these ions according to ionic radius. Ca2+, P3-, S2-, CI- , K+ 
Rank these ions according to ionic radius: Br -, Sr2+, Rb+, Se2-, As3-
Rank the following ions from largest to smallest ionic radius.Se2-, Y3+, Rb+, Br-, Mo6+
Rank the following ions from the smallest to the largest.a) Mg2+ < Na+ < O2- < F- < N3-b) Mg2+ <  Na+ < F- < O2-  < N3-c)  Na+ < Mg2+ <  F- < O2-  < N3-d) Na+ < Mg2+ < O2- < F- < N3-e) Na+ < Mg2+ < O2- < N3- < F-
Rank these ions by their expected hydration energy.
Arrange the following ions, Sc3+, Cl1-, K1+, S2- in order of increasing ionic size.a. Sc3+ < K1+ < S2- < Cl1-b. K1+ < Sc3+ < Cl1- <  S2-c. Sc3+ < K1+ Cl -1 < S2d. K1+ < Sc3+ < S2- < Cl1-
Rank the ions in order of  increasing size, and explain your ranking: Li +, K+, Na+.
Rank the ions in order of  increasing size, and explain your ranking: Se2-, Rb+, Br -.
Rank the ions in order of  increasing size, and explain your ranking: O 2-, F-, N 3-.
Rank the ions in order of  decreasing size, and explain your ranking: Se 2-, S2-, O 2-.
Rank the ions in order of  decreasing size, and explain your ranking: Te 2-, Cs+, I -.
Rank the ions in order of  decreasing size, and explain your ranking: Sr 2+, Ba2+, Cs+.
Name the element described in the following: Period 3 element whose 2− ion is isoelectronic with Ar.
Name the element described in the following: Alkaline earth metal whose cation is isoelectronic with Kr.
Write the formula and name of the compound formed from the following ionic interaction: The 2+ ion and the 1− ion are both isoelectronic with the atoms of a chemically unreactive Period 4 element.
Write the formula and name of the compound formed from the following ionic interaction: The 2+ ion and the 2− ion are both isoelectronic with the Period 3 noble gas.
Write the formula and name of the compound formed from the following ionic interaction: The 2+ ion is the smallest with a filled d sublevel; the anion forms from the smallest halogen.
Rubidium and bromine atoms are depicted below.Which pair best represents the relative ionic sizes?
Based on their positions in the periodic table, list the following ions in order of increasing radius: K+, Ca2+, Al3+, Si4+.
List the following ions in order of increasing radius: Li +, Mg2+, Br–, Te2–.
Compare both the numbers of protons and electrons present in each to rank the following ions in order of increasing radius: As3–, Br –, K+, Mg2+.
The ionic radii of the ions S2–, Cl–, and K+ are 184, 181, 138 pm respectively. Explain why these ions have different sizes even though they contain the same number of electrons.
Which element has the smallest ionic radius?a. Na+ or Mg2+b. Be2+ or O2-c. F‾ or S2-
Arrange the following isoelectronic series in order of decreasing radius F-, N3-, O2-, Mg2+, Na+ Rank ions from largest to smallest. 
The ion with the smallest diameter is ____a. Mn2+b. Cr2+c. V2+d. Ti2+e. Sc2+ 
Arrange the ions below in order of increasing size. Al3+                P3-                  Mg2+