Classification of Elements and Periodicity Cheatsheet

Cheat Codes & Shortcuts

• Periodic Table: Elements arranged in order of increasing atomic number showing periodicity in properties.
• Periods: Horizontal rows with properties changing gradually.
• Groups: Vertical columns with elements having similar chemical properties.
• Periodic Law: Properties of elements are periodic functions of their atomic numbers.
• Atomic Radius: Decreases across a period, increases down a group.
• Ionization Energy: Energy required to remove an electron; increases across a period, decreases down a group.
• Electron Affinity: Tendency to gain electrons, generally increases across a period.
• Electronegativity: Ability to attract electrons; increases across periods and decreases down groups.
• Metallic and Non-metallic Character: Metals are on left and center, nonmetals on right; metallic character decreases across period.
• Transition Elements: Occupy d-block with variable oxidation states and colored compounds.

Quick Reference Table

Property	Trend Across Period	Trend Down Group
Atomic Radius	Decreases	Increases
Ionization Energy	Increases	Decreases
Electron Affinity	Generally increases	Decreases
Electronegativity	Increases	Decreases
Metallic Character	Decreases	Increases

Advice

Classification and Periodicity Quick Tips

• Periods: Properties change gradually from metallic to non-metallic.
• Groups: Elements share valence electron configuration and chemical properties.
• Atomic Size: Decreases across a period due to increased nuclear charge.
• Ionization Energy: Increases across period, decreases down group.
• Electronegativity: Greatest for fluorine; decreases down groups.

Classification of Elements and Periodicity Quiz

Test your knowledge with 5 questions! You have 30 seconds per question.