Atomic numbers of some elements are 31, 34, 49, 50, 53, 81, 84, and 85. Number of elements in 5th period is ___.

$\begin{array}{r}\mathrm{Z}=49;\text{ E.C }\left[\mathrm{Kr}\right]5{\mathrm{s}}^{2}4{\mathrm{d}}^{10}5{\mathrm{p}}^1\\ \mathrm{Z}=50;\text{ E.C }\left[\mathrm{Kr}\right]5{\mathrm{s}}^{2}4{\mathrm{d}}^{10}5{\mathrm{p}}^2\\ \mathrm{Z}=53;\text{ E.C }\left[\mathrm{Kr}\right]5{\mathrm{s}}^{2}4{\mathrm{d}}^{10}5{\mathrm{p}}^5\end{array}$
$\therefore$Atomic no 49, 50 and 53 are the elements in 5th period