Can the following groups of elements be classified as Dobereiners triad?

CBSE Class 10 CBSE Class 10 Science
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Can the following groups of elements be classified as Dobereiners triad?

  1. Na, Si, Cl
  2. Be, Mg, Ca
    Atomic mass of Be 9; Na 23; Mg 24; Si 28; Cl 35; Ca 40
    Explain by giving reason.

Answer:

  1. No, because all these elements do not have similar properties although the atomic mass of silicon is average of atomic masses of sodium (Na) and chlorine (Cl).
  2. Yes, because they have similar properties and the mass of magnesium (Mg) is roughly the average of the atomic masses of Be and Ca.