Here is the code:
\documentclass[a4paper,12pt]{article}
\pagestyle{empty}
\usepackage{rotating}
\linespread{1.2}
\begin{document}
\begin{sidewaystable}
{
\renewcommand{\arraystretch}{1.5}
\bfseries
\centering
\begin{tabular}{|c|c|c|c|c|c|c|c|c|c|c|c|c|c|c|c|c|c|}
\cline{1-1} \cline{18-18}
H & \multicolumn{16}{|c|}{} & He \\
\cline{1-2} \cline{13-18}
Li & Be & \multicolumn{10}{|c|}{} & Bo & C & N & O & Fl & Ne \\
\cline{1-2} \cline{13-18}
Na & Mg & \multicolumn{10}{|c|}{} & Al & Si & P & S & Cl & Ar \\
\hline
K & Ca & Sc & Ti & V & Cr & Mn & Fe & Co & Ni & Cu & Zn & Ga & Ge & As & Se & Br & Kr \\
\hline
Rb & Sr & Y & Zr & Nb & Mo & Tc & Ru & Rh & Pd & Ag & Cd & In & Sn & Sb & Te & I & Xe \\
\hline
Cs & Ba & * & Hf & Ta & W & Re & Os & Ir & Pt & Au & Hg & Tl & Pb & Bi & Po & At & Rn \\
\hline
Fr & Ra & ** & Rf & Db & Sg & Bh & Hs & Mt & Ds & Rg & Cn & Uut & Uuq & Uup & Uuh & Uus & Uuo \\
\hline
\end{tabular}
}
\end{sidewaystable}
\end{document}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
And here is the resulting table:
