The number of elements which should be theoretically present in 8th, period of the modern Iong form of periodic table, is:

For the modern Iong form of periodic table, we have,

$\mathrm{ns}(\mathrm{n}-3)\mathrm{g}(\mathrm{n}-2)\mathrm{f}(\mathrm{n}-1)\mathrm{dnp}$

So, the atoms order,

$\begin{array}{ccccc}8s& 5g& 6f& 7d& 8p\\ 2& 18& 14& 10& 6\end{array}$

This is equal to 50.