What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?

The answer to your question is Ionic bonding.

Explanation:

There are three main types of bonding:

- Ionic bonding is when a metal attaches to a nonmetal and the electronegativity is higher than 1.7.

- Covalent bonding is when a non metal attaches to another non metal. and the electronegativity is between 0 and 1.7.

- Metallic bonding is a bond between metals.

In this question, we have      Lithium plus fluorine

Formula                                               LiF    

In this compound there a metal and a nonmetal

Electronegativity    Fluorine = 3.98     Lithium = 0.98

Difference of electronegativity =  3.98 - 0.98 = 3.0

                                             3.0 > 1.7

Then we conclude that the bond is Ionic.