Question

How many nearest neighbours are there for $Si$ and $O$ atoms in quartz crystals?

• A. 4 (Si) ; 2 (O)
• B. 4 (Si) ; 4 (O)
• C. 2 (Si) ; 2(O)
• D. 3 (Si) ; 2(O)

Answer 1

Answer: (A)

Quartz is $ SiO _{2}$ ( silicon dioxide) in which $SiO _{2}$ units are present as giant crystal. In $SiO _{2}$ crystal each Si-atom is surrounded by $4 (O$ -atoms $)$ , i.e. has four nearest neighbours and each $O$ -atom is surrounded by two $Si$ -atoms having two nearest neighbours.