Lithium ions have a charge of +1 and fluoride ions have a charge of -1. The formula unit for lithium fluoride is LiF, which means that the lithium and fluoride ions are present in a 1:1 ratio. So the positive and negative charges cancel each other, and the compound lithium fluoride is neutral.
An object's velocity can be described by it's direction. Because velocity is a vector. Besides velocity and acceleration are different units they can't be described by each other.
