Although fluorine is far more electronegative than silicon and sulfur, $\text{SF}_4$ has an overall dipole but $\text{SiF}_4$ does not. Suggest a reason for this difference.
Predict whether each of the following molecules has an overall dipole or not. Put a tick in the correct column for $\text{BCl}_3$, $\text{PCl}_3$, $\text{CCl}_4$ and $\text{SF}_6$.
Boron and silicon are the two elements beside carbon in the periodic table. $\text{CCl}_4$ does not react with water, but $\text{BCl}_3$ and $\text{SiCl}_4$ do react.
Suggest a reason for this difference in reactivity.
Construct equations to show how these two chlorides react with an excess of water: $\text{BCl}_3$ and $\text{SiCl}_4$.
When $\text{SiCl}_4$ reacts with a small amount of water, it forms an oxychloride $X$, $\text{Si}_x\text{Cl}_y\text{O}_z$. The mass spectrum of $X$ contains peaks at mass numbers 133, 149, 247, 263 and 396. (You should assume that the species responsible for all these peaks contain only the $^{16}\text{O}$, the $^{35}\text{Cl}$ and the $^{28}\text{Si}$ isotopes.)
Use these data to deduce the molecular formula of $X$.
Suggest the structures of the fragments responsible for the peaks at the following mass numbers: 133, 247 and 263.
Hence suggest the displayed formula of $X$.