Ice is a crystal formed by orderly arrangement of water molecules, and water molecules are connected by hydrogen bonds to form a very "open" (low density) rigid structure. Recently, the distance between O-O nuclei of water molecules is 0.276nm, and the O-O-O bond angle is about 109, which is very close to the bond angle of ideal tetrahedron 109 28'.
However, the O-O distance between adjacent but not directly combined water molecules is much larger, and the farthest distance is 0.347nm. Each water molecule can combine with four other water molecules to form a tetrahedron structure, so the coordination number of water molecules is 4.
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Ice is the solid form of water in nature. Under normal pressure, when the temperature is higher than zero degrees Celsius, the ice will begin to melt and become liquid water. A Japanese research team found that when the ice began to melt, a water molecule in the crystal began to break away from the crystal, and the related mechanism was helpful to understand the structural change mechanism of protein containing water.
If the ice is irradiated with strong light such as electric light, the inside of the ice will melt and appear a shape similar to snow crystal, which is called "ice flower". In order to investigate the phenomenon of ice melting from the inside, researchers from Japan Institute of Molecular Science and Okayama University calculated by computer what happens to ice formed by about 1000 water molecules when heated.
The crystallization of ice is a hexagonal regular arrangement of water molecules. After heating, at first, a water molecule leaves the crystallization and starts to move freely, but this water molecule will not return to its original position, resulting in the distortion of the crystallization.