Atomic and Ionic Radii Quiz: Test Atomic Size Trends
Quick, free chemistry quiz on atomic size trends. Instant results.
This quiz helps you practice atomic and ionic radii trends, compare ion sizes across periods and groups, and spot patterns in isoelectronic series. You will also review what drives a decreasing atomic radius and how charge affects size. For more practice, try our atomic structure quiz, explore a deeper structure of the atom quiz, or tackle targeted atomic structure quiz questions.
Study Outcomes
- Understand Ion Size Determinants -
Identify how effective nuclear charge, electron shielding, and electron - electron repulsions combine to influence the sizes of cations and anions.
- Compare Isoelectronic Species -
Analyze ionic radii within an isoelectronic series to rank species by size and explain the underlying nuclear charge effects.
- Predict Atomic Radii Trends -
Use periodic table positions to forecast how atomic radii change across periods and down groups, recognizing the impact of principal quantum shells.
- Evaluate Anomalies in Trends -
Detect exceptions to general atomic radii trends caused by subshell configurations and variations in electron shielding.
- Apply Quiz Feedback for Improvement -
Leverage instant scoring and detailed feedback from the atomic structure quiz to identify knowledge gaps and refine chemistry skills.
Cheat Sheet
- Ion Size vs. Charge -
When you tackle an ion sizes quiz, remember that losing electrons (forming cations) reduces electron - electron repulsion and shrinks the radius, while gaining electrons (forming anions) expands it. For example, Na❺ (102 pm) is smaller than neutral Na (154 pm), which in turn is smaller than F❻ (136 pm). This relationship is well-documented in Purdue University's general chemistry resources.
- Isoelectronic Series Ordering -
Isoelectronic species have the same electron count but different nuclear charges, so radii decrease with increasing proton number. For instance, in the O²❻, F❻, Na❺, Mg²❺ series, radii follow Mg²❺ < Na❺ < F❻ < O²❻, as confirmed by Royal Society of Chemistry data. A handy mnemonic is "More protons, more pull, more small" to remember this trend.
- Periodic Atomic Radius Trend -
On an atomic radii trend test, you'll see radii decrease across a period due to rising effective nuclear charge (Z_eff) and increase down a group as additional electron shells are added. For example, atomic radius drops from K (220 pm) to Ca (197 pm), then jumps from Ca to Sr (215 pm). Cambridge University chemistry lectures cover these patterns in detail.
- Effective Nuclear Charge (Z_eff) Calculation -
Understanding Z_eff is crucial for both ion sizes and atomic radii questions: Z_eff ≈ Z − S (where S is the shielding constant from Slater's rules). For sodium, Z=11 and S≈10, so Z_eff≈1 for the 3s electron, explaining its larger size compared to magnesium's 3s electrons (Z_eff≈2). This calculation is a staple in chemistry atomic structure practice materials.
- Smart Quiz Practice Techniques -
When prepping for an atomic structure quiz, combine ion sizes quiz items, isoelectronic species questions, and atomic radii trend test problems, using active recall and spaced repetition. Flashcards with sample data (e.g., compare Cl❻ vs. Ar) and instant feedback tools help reinforce concepts quickly. The American Chemical Society suggests timed quizzes to build speed and accuracy.