Predict the formulae of the stable binary compounds that would be formed by the following pairs of compounds :
(a) `Al` and `Cl` , (b) `Mg` and `I`
(c ) Element `113` and `F` , (d) `Si` and `S` (e) Element `119` and oxygen.

Explanation

a. `Al` is an element of group `13` with `3e^(-)` in its valence shell. Therefore, its valence `= 3`.
`Cl` is an element of group `17`, with `gt 7e^(-)` in its valence shell therefore its valence `= 8 - 7 = 1`.
`:.` Formula `= AlCl_(3)`
b. `Mg` is an element of group `2`, with `2e^(-)` in its valence shell. Therefore, its valence `= 2`.
`I` is an element of group `17`, with `gt 7e^(-)` in its valence shell. Therefore, its valence `= 8 - 7 = 1`.
`:.` Formula `= MgCl_(2)`
`|{:("Lanthanide series","Atomic number" 57-71,"Group" 3,"6th Period",),("Actinide series","Atomic number" 89-103,"Group" 3,"7th Period",):}|`
Element `(X)` (At. no.` = 113`) lies in group 13, and 7th period. Hence, its outer shell electronic configuration is `7s(2) 7p^(1)`, therefore its valence `=3`.
F belongs 17 with `7e^(e-)` in its valence shell.
Therefore, its valence `= 8-7 = 1`.
`:.` Formula `= X F_(3)`
(d) `Si` and an element of group 14 with `4^(e-)` in its valene shell. Therefore, its valence `= 4`.
S is an element of group 16 with `6e^(-)` in its valence shell. Therefore, its valence `= 8-6=2`.
`:.` Formula `= Si S_(2)`
e. Element `(X) (Z = 119)` lies in group 1, and 8th period. Hence its outer shell electronic configuration is `8s^(1)`. Therefore, its valence `=1`.
O is an element of group 16 with `6e^(-)` in its valence shell. Therefore, its valence `= 8-6 = 2`.
`:.` Formula `= X_(2)O`