The elastic potential energy stored in the stretched rubber band changes to kinetic energy.
Explanation:
Joshua hooks a rubber band between his thumb and forefinger. He moves his fingers apart, stretching the rubber band---- Here potential Energy is stored which is an energy that the rubber band has because of its position and it's potential to be converted into kinetic energy.
With a quick, sudden motion, he bends his thumb forward so that the rubber band slips off----The elastic potential energy stored in the stretched rubber band will change to kinetic energy, which is the Energy in Motion and work needed to accelerate the rubber band from rest to its stated or new position.
Hydrogen has no other electron hence there is no screening of the valence electron by inner electrons. It is the lightest known element with a relative molecular mass of 2. Screening effect refers to the fact that inner or core electrons prevent the outermost electron from feeling the attractive force of the nucleus.