Describe the basic character of the oxides of third period elements across the period from left to right.

(N/A) As we move from left to right across the third period,the basic character of the oxides decreases.
$1$. $Na_2O$ and $MgO$ are basic in nature.
$2$. $Al_2O_3$ and $SiO_2$ are amphoteric in nature (they show both acidic and basic properties).
$3$. $P_4O_{10}$,$SO_3$,and $Cl_2O_7$ are acidic in nature.
This trend occurs because the electronegativity of the elements increases from left to right,leading to a decrease in the ionic character and an increase in the covalent character of the oxides.