The ‘Law of Octaves' was proposed by ______. 

The correct answer is John Newlands.

Key Points

• John Newlands was an English chemist who proposed the 'Law of Octaves' in 1864.
• He observed that when elements are arranged in order of increasing atomic mass, every eighth element had properties similar to the first.
• This pattern was one of the earliest attempts to classify the elements and showed a periodicity in their properties.
• Newlands' Law of Octaves was initially not accepted by the scientific community, but it laid the groundwork for the development of the modern periodic table.

Additional Information

• Periodic Table:
  • The modern periodic table arranges elements by increasing atomic number, which is the number of protons in an atom's nucleus.
  • Elements with similar chemical properties are grouped in columns known as groups or families.
  • The periodic table is divided into metals, nonmetals, and metalloids based on their properties.
• Mendeleev's Periodic Table:
  • Dmitri Mendeleev, a Russian chemist, published a more comprehensive periodic table in 1869.
  • Mendeleev's table left gaps for elements that were yet to be discovered, predicting their properties based on periodic trends.
  • His periodic table was widely accepted because it could explain the properties of known elements and predict new ones.
• Henry Moseley:
  • Henry Moseley, an English physicist, discovered the atomic number of elements in 1913 through X-ray spectroscopy.
  • Moseley's work led to the reorganization of the periodic table based on atomic number rather than atomic mass.
• Döbereiner's Triads:
  • Johann Wolfgang Döbereiner, a German chemist, identified groups of three elements (triads) with similar chemical properties in 1829.
  • The middle element of each triad had properties that were approximately an average of the other two.
  • Döbereiner's triads were an early attempt to classify elements based on their properties.