Final answer:
Water can form a dome-like structure on a penny due to its cohesive property, which is the result of hydrogen bonding between water molecules, and leads to surface tension that holds the molecules together at the surface.
Step-by-step explanation:
The property of water that allows it to form a dome-like structure on top of a penny is called cohesion. Cohesion is due to the attraction between water molecules, which is the result of hydrogen bonding. This attraction keeps the molecules together at the liquid-air interface, leading to a phenomenon known as surface tension. Surface tension is responsible for the ability of water to form droplets and maintain a dome-like shape without spilling over, as well as allowing objects like paper clips and needles to float on water if placed gently.
Surface tension and cohesion are critical not only for these curious observations but also for natural processes, such as enabling water to travel from the roots up to the leaves in plants, which is vital for their nourishment and survival.