The answer is so it didn't burn.
The <span>process
melts an ore to separate useful metals from the rest of the elements in the ore
is called smelting. The ore is heated beyond its melting point to extract the
metal with the help of oxidizing agents such as air or reducing agents such as
coke. </span>
You need to follow the atomic radius trend, the atomic radius decreases as you go across the period, and the atomic radius increases as you go down a group.
Between Sodium, Magnesium, Aluminum, silicon, and phosphorus, Sodium has the biggest atomic radius.
