Discuss the reactivity of group $14$ elements towards water and halogens.

(N/A) Reactivity towards water:
Carbon,silicon,and germanium are not affected by water. Tin decomposes steam to form dioxide and dihydrogen gas:
$Sn + 2H_2O \xrightarrow{\Delta} SnO_2 + 2H_2$
Lead is unaffected by water,likely due to the formation of a protective oxide film.
Reactivity towards halogens:
- These elements form halides with the general formulas $MX_2$ and $MX_4$ (where $X = F, Cl, Br, I$).
- Except for carbon,all other members react directly with halogens under suitable conditions to form halides. Most $MX_4$ halides are covalent.
- The central metal atom in these halides typically undergoes $sp^3$ hybridization,resulting in a tetrahedral geometry. Exceptions include $SnF_4$ and $PbF_4$,which are ionic.
- $PbI_4$ does not exist because the $Pb-I$ bond energy is insufficient to unpair the $6s^2$ electrons and promote one to a higher orbital to achieve four unpaired electrons.
- Heavier members ($Ge$ to $Pb$) can form $MX_2$ halides,with the stability of dihalides increasing down the group.
- Regarding thermal and chemical stability,$GeX_4$ is more stable than $GeX_2$,whereas $PbX_2$ is more stable than $PbX_4$. Except for $CCl_4$,other tetrachlorides are easily hydrolyzed by water because the central atom can accommodate the lone pair of electrons from the water molecule in its vacant $d$-orbitals.
- Hydrolysis can be illustrated by $SiCl_4$,which reacts by accepting a lone pair of electrons from water into its $d$-orbitals,ultimately forming $Si(OH)_4$:
$SiCl_4 + 4H_2O \rightarrow Si(OH)_4 + 4HCl$