Answer
$ScN$
Work Step by Step
A Scandium ion, the problem states, has a charge of +3. Nitrogen, in order to gain the electron configuration of the nearest noble gas, Neon, must gain three electrons, making the charge of a Neon ion -3. Because the compound formed between Nitrogen and Scandium must be equal, the charges of the two must cancel out. However, the two ions have opposite charges (-3 and +3), so there must be one of each ion. Thus, the compound is ScN.
