What causes a rearrangement of atoms?

When a atom is unstable (It wants to gain or lose a valence electron)

can you attach a picture of the lettuce? : )

under a microscope, cancer cells may look very different from normal cells. they often have different sizes and some may be larger than normal while others are smaller. cancer cells are often abnormally shaped and the control centre of the cell (the nucleus) may have an abnormal appearance.

i think? ?