Key Concepts: Periodic Table Arrangement

Core Definitions

• Periods: Horizontal rows on the periodic table; elements in the same period have the same number of energy levels.
• Groups/Families: Vertical columns; elements in the same group have similar chemical properties and the same number of valence electrons.
• Metals: Found on the left side; good conductors, malleable, ductile, shiny.
• Nonmetals: Found on the right side; poor conductors, brittle as solids, dull.
• Metalloids: Found along the staircase line; have properties of both metals and nonmetals (e.g., silicon).
• Atomic Number Order: Elements are arranged by increasing atomic number from left to right.