I just got "Organic Chemistry Odyssey" and started working on the problems.

One nomenclature problem has:

1) 2-bromo-3-flourobutane

the other one is:

2) 2-chloro-3-iodobutane

??????????

Electronegativity= F>Cl>Br>I
Molecular Weight = I>Cl>Br>F

How am I supposed to name dihaloalkanes?? (*I took out R/S configurations...I just need to know the numbering)

it's alphabetical. Chlorine before Iodine. Bromine before Fluorine

Alphabetical only if each substituent is equally far from the beginning of the end of the chain. Lowest number for first substituent is rule #1 for unbranched alkanes. If equal possibilities, then alphabetical.