Science
Periodic trends.
Definition
Periodic trends are predictable patterns in element properties across the periodic table. Atomic radius decreases across a period and increases down a group. Ionization energy and electronegativity generally increase across a period and decrease down a group. These trends result from changes in nuclear charge and electron shielding.
Examples
Real-world.
- 1 Fluorine having the highest electronegativity of all elements
- 2 Francium having the largest atomic radius among naturally occurring elements
- 3 Noble gases having the highest ionization energies in their respective periods
Key Fact
Across a period: atomic radius ↓, ionization energy ↑, electronegativity ↑. Down a group: opposite.
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