Newton’s 3rd Law states… a. Objects in motion stay in motion and objects at rest stay at rest
b. Force is equal to mass times acceleration
c. For each action there is an equal and opposite reaction

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

in the analysis of systems that involve fluid flow, we frequently encounter the combination of properties u and pv.