Identify the false statement about atomic and ionic radii. (LO 6.3) (a) I- has a larger radius than Br- (b) Ba2+ has a smaller radius than Ba (c) Te has a larger radius than Te2- (d) Sr2+ has a smaller radius than Se2-

Verified step by step guidance

1. Step 1: Understand the concept of atomic and ionic radii. Atomic radius refers to the size of a neutral atom, while ionic radius refers to the size of an ion. When an atom gains electrons to form an anion, its radius typically increases due to increased electron-electron repulsion. Conversely, when an atom loses electrons to form a cation, its radius typically decreases due to reduced electron-electron repulsion.
2. Step 2: Analyze statement (a): I- has a larger radius than Br-. Compare the ionic radii of I- and Br-. Both are anions, and I- is located below Br- in the periodic table, which generally means it has a larger radius due to the addition of an electron shell.
3. Step 3: Analyze statement (b): Ba2+ has a smaller radius than Ba. Compare the ionic radius of Ba2+ with the atomic radius of Ba. Ba2+ is a cation formed by losing two electrons, which typically results in a smaller radius compared to the neutral atom.
4. Step 4: Analyze statement (c): Te has a larger radius than Te2-. Compare the atomic radius of Te with the ionic radius of Te2-. Te2- is an anion formed by gaining two electrons, which typically results in a larger radius compared to the neutral atom. This statement seems incorrect based on the general trend.
5. Step 5: Analyze statement (d): Sr2+ has a smaller radius than Se2-. Compare the ionic radius of Sr2+ with the ionic radius of Se2-. Sr2+ is a cation, and Se2- is an anion. Generally, cations have smaller radii than anions, especially when comparing ions from different groups.

Key Concepts

Atomic Radius

The atomic radius is a measure of the size of an atom, typically defined as the distance from the nucleus to the outermost electron shell. Atomic radii generally increase down a group in the periodic table due to the addition of electron shells, while they decrease across a period due to increased nuclear charge, which pulls electrons closer to the nucleus.

Ionic Radius

The ionic radius refers to the size of an ion in a crystal lattice. Cations (positively charged ions) are smaller than their neutral atoms because they lose electrons, resulting in reduced electron-electron repulsion and a stronger pull from the nucleus. Conversely, anions (negatively charged ions) are larger than their neutral atoms due to the addition of electrons, which increases repulsion among electrons.

Trends in Ionic and Atomic Radii

Understanding the trends in ionic and atomic radii is crucial for comparing different elements and their ions. Generally, as you move down a group, both atomic and ionic radii increase, while moving across a period results in a decrease in atomic radius and a more complex pattern for ionic radii, influenced by the charge of the ions. This knowledge helps in evaluating statements about the relative sizes of different ions and atoms.