The atomic number 13 implies this electronic configuration 1 s2 2s2 2p6 3s2 3p1.
There are three electrons in the outer shell (3s2 3p1)which are those that the atom can loose more easily (precisely for having the higher energy or being farther from the nucleus)
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.
