All of the following require breaking and forming chemical bonds except

freezing ice
a plant decaying
a piece of silver tarnishing
roasting a marshmallow

All of the following require breaking and forming chemical bonds except roasting a marshmallow. Freezing ice, a plant decaying and a piece of silver tarnishing are examples of breaking and forming chemical bonds.

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.