Question

how did the work of dmitri mendeleev differ from that of john newlands in the development of the periodic table?
mendeleev arranged the elements according to increasing atomic mass.
mendeleev predicted elements that would later be discovered.
mendeleev identified elements that had similar properties.
mendeleev organized elements into triads based on their properties.

Explanation:

1. Analyze the first option: Both Mendeleev and Newlands arranged elements by increasing atomic mass, so this is not a difference.
2. Analyze the second option: Mendeleev left gaps in his periodic table and predicted the existence of elements that were later discovered (like gallium, germanium), while Newlands did not do this. This is a key difference.
3. Analyze the third option: Both identified elements with similar properties (Newlands with his law of octaves, Mendeleev with periodicity), so this is not a difference.
4. Analyze the fourth option: Organizing into triads was done by Dobereiner, not Mendeleev or Newlands, so this is incorrect.

Answer:

B. Mendeleev predicted elements that would later be discovered.