Iron which resembles Cobalt and Nickel in properties has been placed far away from these elements. This was one of the limitations of:

The correct answer is Newlands' law of octaves.

Key Points

• The56 elements that were then known were examined in 1864 by British scientist John Newlands.
• According to the law of octaves, every eighth element possesses characteristics that are identical when the elements are ordered in ascending order of atomic mass.
• Cobalt and nickel are isolated from iron, which shares many of its physical characteristics.
• The Law of Octaves was no longer relevant with the discovery of noble gases.
• Newland's Law of Octaves' limitations:
  •  In Newland's periodic table, several elements fit into the same positions.
  • Nickel and cobalt, for instance, were put in the same slot.
  • Elements with dissimilar properties were grouped together.
  • For instance, several metals, such as cobalt, nickel, and platinum, were classed with halogens.
  • The octaves of Newland's law was only accurate for elements up to calcium.
  • It was impossible to fit elements with larger atomic masses within octaves.
  • The octave pattern could not accommodate the later found components.
  • As a result, there was no room for the discovery of new elements using this system of classifying elements.

Additional Information

• Mendeleev's periodic table:
  • Mendeleev stated that "Element characteristics are a periodic function of their atomic weight" in his renowned periodic law.
• Dobereiner's triads:
  • Johann Wolfgang Dobereiner discovered groups of elements having related properties and named them Dobereiner's triads.
• Modern periodic table:
  • The elements are organized in the current periodic table in order of increasing atomic number.
  • The periodic table has groups and periods.