why does silica form a giant structure and how?

Answer 1

Silica is a large network covalent structure with an average ratio of 1 Silicon and 2 Oxygens (SiO2). Each Silicon is actuall attached to 4 oxygens and each oxygen to 2 Silicons. It is a fully oxygenated form of Silicon and is stable at high temperatures (i.e. we melt it and make glass).

Answer 2

How: Silicon has a valence of 4; oxygen is 2. Silicon is like an electrical connector with four sockets in it. Imagine oxygen as a short cord with two plugs. Plug all the plugs into all the sockets and you have a three-dimensional interconnected network of Si's and O's as far as the eye can see.

Why: Si is a large atom and C is a small one. When O forms bonds with C to make CO2, The p-orbitals have room to overlap top and bottom and form C=O bonds. Si is too big for that, so Si tends to form Si-O bonds. So SiO2 is really (SiO2)sub n, where n is a very large number.

Answer 3

It forms an ionic structure. This is because each Si will have two oxygen and two other oxygen will ahve that Si, they just form a big lattice like if you had loads of south pole and north pole magnets.

Answer 4

I have a few bags of silica and was not aware that they could suddenly turn into a giant structure.

Thanks to your info I have now safely moved them outside!