Ionic Radii
Studies the size of cations and anions, comparing them to their parent atoms and analyzing their periodic trends.
What is Ionic Radii?
The effective distance from the nucleus of an ion to the outermost electron shell, as determined by the inter-nuclear distance in an ionic compound.
Key points
- Define ionic radii.
- Explain the factors affecting ionic radii.
- Compare the sizes of cations, anions, and their parent atoms.
- Analyze the trends of ionic radii across periods and down groups.
Common exam trap
Confusing ionic radius with atomic radius.
Definitions
- Term
Ionic Radii
- Meaning
The effective distance from the nucleus of an ion to the outermost electron shell, as determined by the inter-nuclear distance in an ionic compound.
- Term
Isoelectronic Species
- Meaning
Atoms or ions that have the same number of electrons.
- Term
Effective Nuclear Charge (Zeff)
- Meaning
The net positive charge experienced by an electron in a multi-electron atom or ion, considering shielding by other electrons.
Learning objectives
Define ionic radii.
Explain the factors affecting ionic radii.
Compare the sizes of cations, anions, and their parent atoms.
Analyze the trends of ionic radii across periods and down groups.
Determine the relative ionic radii of isoelectronic species.
Prerequisites
Atomic Structure
Periodic Classification of Elements
Effective Nuclear Charge
Isoelectronic Species
Common mistakes
Confusing ionic radius with atomic radius.
Not considering the charge of the ion when comparing sizes.
Incorrectly applying periodic trends without accounting for ionization.
Assuming all ions of the same element have the same radius.
Keywords
Ionic Radius
Cation
Anion
Atomic Radius
Effective Nuclear Charge
Electron Repulsion
Isoelectronic Series
Periodic Trends
Practice preview
Which of the following species has the largest ionic radius?…
easy
The ionic radii of N3-, O2-, and F- are in the order:…
easy
Which of the following statements about ionic radii is INCORRECT?…
easy