To float the needle, gently lower it to the water's surface with a pair of tweezers. If you have ever looked closely at drops of water, you will know that drops try to form spherical shapes. Because of gravity's attraction, drops that cling to an eye dropper, for example, are stretched out. However, when the drops fall they become spherical. The shape of a water drop is a result of surface tension.
Water is composed of molecules consisting of two hydrogen atoms and one atom of oxygen.
These molecules attract each other. In the middle of a drop of water, molecules attract each other in all directions so no direction is preferred. On the surface, however, molecules are attracted across the surface and inward. This causes the water to try to pull itself into a shape that has the least surface area possible-the sphere. Because of gravity, drops resting on a surface, like water drops on a well-waxed car, flatten out somewhat like the figure above.