Question

Write characteristics of modern periodic table.

Answer 1

Characteristics of the Modern Periodic Table

• 
  Modern Periodic Law: Properties of elements are the periodic functions of their
  atomic numbers (Z).
• 
  Arrangement: Elements arranged in
  7 periods (rows) and
  18 groups (columns).
• 
  Blocks: s-, p-, d- and f-block classification based on valence electron subshell.
• 
  Metals → Non-metals: Metallic character decreases from left to right; non-metallic character increases.
• 
  Valence & configuration: Elements in the same group have similar valence-shell configurations and hence similar properties.
• 
  Periodic trends:
  • Atomic radius: ↓ down a group, ↑ left to right it
    decreases.
  • Ionization enthalpy & electronegativity: generally
    increase across a period,
    decrease down a group.
• 
  Noble gases: Group 18 (complete valence shells) placed at the extreme right.
• 
  Lanthanides & Actinides: Shown separately below the table as f-block series.
• 
  Isotopes: Occupy the same position since arrangement is by atomic number, not atomic mass.