Final answer:
The basic structural unit of silicates is SiO4, which is a silica tetrahedron comprising a central silicon atom surrounded by four oxygen atoms.
Step-by-step explanation:
The basic structural unit of silicates is SiO4, known as the silica tetrahedron. This structure consists of a central silicon atom surrounded by four oxygen atoms at the corners of the tetrahedron. Each silicon atom is sp3-hybridized and can form discrete units or share oxygen atoms with other tetrahedra.
The silica tetrahedron has a net charge of -4, owing to silicon's charge of +4 and the four oxygen ions each with a charge of -2. When the tetrahedra link together, they form various silicate mineral structures.