Which of the following scientists grouped the elements into triads?

The correct answer is Johann Wolfgang DobereinerKey Points

• Johann Wolfgang Döbereiner, a German chemist, was one of the first to classify elements based on their similar properties.
• In 1829, he observed that certain groups of three elements had similar chemical properties and
  • that the atomic mass of the middle element was roughly the average of the other two.
• These groups of three elements became known as "Döbereiner’s Triads."
• For example:
  • Lithium, Sodium, Potassium: In this triad, sodium’s atomic mass is the average of lithium and potassium.
  • Chlorine, Bromine, Iodine: These elements also formed a triad with similar chemical behavior.

Additional Information

•  John Newlands
  • Newlands proposed the Law of Octaves, where he arranged elements in increasing order of atomic mass and noticed that every eighth element had similar properties.
  • His work was an important step toward the development of the modern periodic table, but it was initially criticized for not being applicable to all elements.
  • His classification system was later recognized as a precursor to Mendeleev’s work.
• Henry Moseley
  • Moseley established the concept of atomic number, which is the number of protons in the nucleus of an atom.
  • His work showed that elements are better arranged by increasing atomic number rather than atomic mass, leading to a more accurate periodic table.
  • His research resolved inconsistencies in Mendeleev’s periodic table.
• Dmitri Mendeleev
  • Mendeleev is credited with creating the first widely recognized periodic table in 1869.
  • He arranged elements by increasing atomic mass and left gaps for undiscovered elements, predicting their properties with great accuracy.
  • Mendeleev’s periodic law laid the groundwork for modern chemistry.