Question

List any three observations which passed a challenge in Mendeleev periodic table?

Answer 1

- Position of hydrogen in the first group among metal though it is non-metal.

- Placing the elements with higher Atomic mass before the elements with lower Atomic mass.

- No places were left in between two groups for isotopes.

Answer 2

The observations which posed a challenge to Mendeleev periodic table are ;

- Position of hydrogen in the first group among metal though it is non-metal.

- Placing the elements with higher Atomic mass before the elements with lower Atomic mass.

- No places were left in between two groups for isotopes.