First, let's visualize the structure of 1,1,4-trifluorohept-2-yne. This indicates that there is fluor in carbon 1 twice and in carbon 4, there is a triple bond in carbon 2 because of the "2-yne" (yne is telling us that is a triple bond) and the principal chain has seven carbons (hept). Remember that carbon is bonded fourth times:
You can see that we have 7 carbon atoms, 9 hydrogen atoms, and 3 fluorine atoms.
