What is the name of the compound Al2S3? What is the formula of iodine heptafluoride?

Aluminum ($\text{Al}$) is a metal from Group 13, forming a $\text{Al}^{3+}$ ion. Sulfur ($\text{S}$) is a nonmetal from Group 16, forming a $\text{S}^{2-}$ ion.

The cation is named first, followed by the anion with an "-ide" suffix. Since aluminum is a main group metal with a fixed charge, no Roman numeral is needed.

The name of the compound $\text{Al}_2\text{S}_3$ is aluminum sulfide.

The name "iodine heptafluoride" indicates the elements iodine ($\text{I}$) and fluorine ($\text{F}$).

"Iodine" implies one iodine atom (the prefix "mono-" is usually omitted for the first element). "Heptafluoride" indicates seven fluorine atoms (hepta- means 7).

Combine the symbols and subscripts.

The formula for iodine heptafluoride is $\boxed{\text{IF}_7}$.