http://www.ck12.org Chapter 2. Matter
2.12 Solids
- Identify properties of matter in the solid state.
- Compare crystalline and amorphous solids.
What do you think this picture shows? Could it be a delicate glass sculpture created by a talented artist? It’s delicate
alright, but it’s not glass, nor was it created by an artist. It’s actually made of ice and it’s a work of nature. Now can
you guess what it is? It’s a snowflake, as viewed under a microscope.
Snowflakes and Other Solids
A snowflake is made of ice, or water in the solid state. Asolidis one of four well-known states of matter. The other
three states are liquid, gas, and plasma. Compared with these other states of matter, solids have particles that are
much more tightly packed together. The particles are held rigidly in place by all the other particles around them so
they can’t slip past one another or move apart. This gives solids a fixed shape and a fixed volume.
Types of Solids
Not all solids are alike. Some are crystalline solids; others are amorphous solids. Snowflakes are crystalline solids.
Particles of crystalline solids are arranged in a regular repeating pattern, as you can see in the sketch inFigure2.21.
The repeating particles form a geometric shape called a crystal. You can watch a snowflake crystal forming at the
following URL: http://www.its.caltech.edu/~atomic/snowcrystals/movies/movies.htm. Another crystalline solid is
table salt (sodium chloride). Crystals of table salt are pictured in theFigure2.21.