Why is glass so sharp after it shatters

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Why is glass so sharp after it shatters

In: Chemistry

Glass is very brittle and has an irregular internal structure with multiple weak points.

When it’s shattered, the weak points break first. Straight fracture lines connect these weak points to form thin, sharp slivers.

Simply put, its the characteristic of all brittle materials. Non-brittle materials like say a piece of copper wire can be bent several time before it breaks, at microscopic level these materials are a cluster of crystal grains that can slide. This allows non-brittle to be bent.

Glass on the other hand is classified as brittle, it doesn’t really have crystalline microstructure, rather its composed of network of silicate chains. These chains are highly rigid and cannot really slide over each other like in the case of microstructural grain of copper wire.

Because of this lack of sliding, any impact force causes a crack in these network of chains in glass unlike in a copper plate which receives a dent. This is what we call brittleness of glass.
Furthermore, this crack propagates rather quickly and involves breaking of bonds at the atomic level. Thus the edge of a shattered glass is likely just single atom wide, making it extremely sharp.