Water molecules are made up of 1 Oxygen atom and 2 Hydrogen atoms. When these atoms come together to make water they make a triangle-like shape. Oxygen sits in the middle of the triangle. The two Hydrogen atoms are on two of the points of the triangle. The third point is where the extra outer electrons of Oxygen are; these are the electrons that are not being shared with the 2 Hydrogens in the outer layer.
When in this shape, the two Hydrogen atoms make that side of the triangle more positively charged and the electrons sitting at the opposite point make that side more negatively charged. Because of this special shape, water molecules like to stick together with each other and other charged things, like the side of a glass.
So when you pour water out of a glass slowly some water has a chance to stick to the glass. Eventually there is so much water that it weighs too much for that little charge to hold and the water falls off the glass.
This is only part of the reason this happens. Another part of the reason is a special way fluids can move called laminar flow.
Latest Answers