what is the valency of silicon ? is it positive or negative ? is it a metal or non-metal or a metalloid ?

Please note that valency of an element or an ion does not possess any charge. It is the charge on an ion which is either positive or negative. The atomic number of silicon is 14, and its electronic configuration is 2, 8, 4. Thus it has four electrons in its valence shell and needs four more to complete its octet. So, the valency of silicon is 4. It is a metalloid.