Question

which element has the highest IP in periodic table?

why isotopes and isobars are not placed in periodic table?

Answer 1

1)Excluding Noble gases,
since fluorine is the most electronegative element,thus it possess the highest ionisation potential.

2)Since H G J Moseley gave a modern periodic table in which atomic no. was the most fundamental property. Therefore elements with same atomic no. that is isotopes were not placed separately.
While Isobars are placed separately ,because isobars have different atomic no. and same mass no.