Answer
Name of the compound: 3-Fluoro-4-ethylhexane.
Step-by-step explanation
This structure contains an ethyl group and a halogen atom attached to a backbone of six carbon atoms.
Number the carbon backbone. (Number carbon atoms but not functional groups- e.g., atoms of fluorine- attached to them.) Keep in mind that the priority of halogen atoms are higher than that of branched alkane chains. You should number the carbon atoms to minimize the index number on groups of the highest priority.
Numbering the backbone from the left to the right gives the carbon attached to the fluorine atom an index of 4, as seen on the picture. Numbering the backbone in the opposite direction gives the same carbon atom an index of 3.
You are supposed to minimize the index number of the carbon atom attached to fluorine. You should therefore number the atoms starting from the right hand side of the structure.
The carbon atom attached to the fluorine atom thus ends up with an index of 3. Accordingly, the carbon atom connected to the two-carbon ethyl group ends up with an index of 4.
The carbon backbone contains six carbon atoms connected with carbon-carbon single bonds. Thus it is called a hexane.
Place names of the functional groups in front of that of the backbone. Similar to their indexes, functional groups should be named in the order of their priority. The prefix for fluorine fluoro- should thus be placed in front of ethyl-, which stands for the two-carbon alkane substitute for hydrogen.
Putting parts together gives the systematic name of this compound (with no space in between) :
3-Fluoro-4-Ethylhexane