Covalent molecules

The dots, crosses and open circles only show which atom each electron came from. All electrons are the same: once shared, a pair belongs to both atoms.

The board shows only the outer shells, and the molecules lie flat. Real molecules have shapes in three dimensions, which this course doesn’t need.

The moves are slowed down. Atoms don’t come from a box: in a real reaction, the bonds of the starting substances break and new ones form.

With reduced motion, each move finishes at once.