Day 1: Light: day-night cycle

Prior to God creating the “expanse”, the earth was an undifferentiated object, probably a sphere, comprised of water; rotating in a 24-hour day night cycle, illuminated by an unspecified light source later to be replaced by the sun on the fourth day of the creation work.

The hydrogen and oxygen molecules comprising water contain all necessary atomic particles to form all other molecules of the physical creation. That said, since God was creating everything out of nothing, He was not constrained to reformat the atomic particles comprising the water into other elements. He could just as easily created any or all the materials He fashioned from new matter and energy.