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# 2.2.1: Trends in Size (Problems)

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PROBLEM $$\PageIndex{1}$$

Based on their positions in the periodic table, predict which has the smallest atomic radius: Mg, Sr, Si, Cl, I.

Answer

Cl

PROBLEM $$\PageIndex{2}$$

Based on their positions in the periodic table, predict which has the largest atomic radius: Li, Rb, N, F, I.

Answer

Rb

PROBLEM $$\PageIndex{3}$$

Based on their positions in the periodic table, list the following atoms in order of increasing radius: Cs, Ca, Rb, Mg

Answer

Mg < Ca < Rb < Cs

PROBLEM $$\PageIndex{4}$$

Based on their positions in the periodic table, list the following atoms in order of increasing radius: Sr, Cl, Ca, Si.

Answer

Cl < Si < Ca < Sr

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PROBLEM $$\PageIndex{5}$$

Based on their positions in the periodic table, list the following ions in order of increasing radius: K+, Ca2+, Al3+, Si4+.

Answer

Si4+ < Al3+ < Ca2+ < K+

PROBLEM $$\PageIndex{6}$$

List the following ions in order of increasing radius: Br, Li+, Te2–, Mg2+.

Answer

Li+ < Mg2+ < Br< Te2–

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PROBLEM $$\PageIndex{7}$$

Which atom and/or ion is (are) isoelectronic with Br+: Se2+, Se, As, Kr, Ga3+, Cl?

Answer

Se, As

PROBLEM $$\PageIndex{8}$$

Which of the following atoms and ions is (are) isoelectronic with S2+: Si4+, Cl3+, Ar, As3+, Si, Al3+?

Answer

Si, Cl3+

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PROBLEM $$\PageIndex{9}$$

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+.

Answer

Mg2+ < K+ < Br < As3–

PROBLEM $$\PageIndex{10}$$

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.

Answer

They have different numbers of protons, which determines their size.

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2.2.1: Trends in Size (Problems) is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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