Semi-Metals:

The obvious trend in the periodic table is in which from left to right, across any period, a elements  modify  from  distinctly  metallic  (Group  IA)  to  distinctly  nonmetallic (Group VIIA).  That change in character is not sharply described, but is gradual. Commonly, elements well to the left of the heavy diagonal line are metals, and these well to the right are nonmetals.  A few of the elements near the line, therefore, exhibit properties of metals under a few conditions and properties of nonmetals under other conditions. These elements are known as the semi-metals and involve silicon (Si), boron (B), germanium (Ge), arsenic (As), and tellurium (Te).   They are commonly categorized as semi-conductors of electricity and are hugely used in electrical elements.