Not easily changed 1.
stable

2.
chemical bonding

3.
valence electrons

4.
ionic bond

5.
covalent bond

I would say when an atom has its valence electron shell filled like a noble gas has, it is not easily changed.

I’m not entirely sure of what you’re asking, but if you’re talking about bonding then it would be an ionic bond that is not easily changed.

Well, if you are moving forward in a direction, then your velocity is your speed with the direction you are moving in. To calculate velocity, you divide your distance traveled by the time it took to travel that distance and you add your direction to it.
So to conclude, 300/100= 3 m/s South