Classification Of Elements

On completion of this lesson, students should be able to:

  • Explain and differentiate between Mendeleev's periodic law and modern periodic law.
  • Explain atomic structures of the elements based on periodic number.
  • Explain the trends followed by elements in a group and a period.


Characteristics of a Group

Valence electrons, valency, atomic size, ionization energy, metallic character, electron-positivity, electron-negativity and reactivity are the characteristics of groups. This note describes about variations in different properties of a group in a periodic table.

Characteristics of a Period

The number of valence electrons in a period increase from 1 to 8 on going from left to right in a period. This note describes about variation in various properties of a period in a periodic table.

Mendeleev's Periodic Table

Mendeleev's periodic law states that "All the physical and chemical properties of the elements are the periodic function of their increasing atomic weight". This note has information about Mendeleev's Periodic Table, its advantages and disadvantages are also discussed.

Modern Periodic Table

Modern periodic law states, "All the physical and chemical properties of an element are the periodic functions of their increasing atomic number". This note has detail information about modern periodic table, its advantages characteristics and components.