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

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.