Solid, in physics and chemistry, one of the three states of matter. The other two states of matter are gas and liquid. A solid tends to maintain its shape without a container. Some solids are harder than others. True solids are crystalline; that is, the atoms of which they are composed are arranged in definite, three-dimensional patterns. They have definite melting temperatures. Some substances, such as glass and tar, that appear to be solid are amorphous—they do not have a crystalline atomic structure. These substances soften and melt over a range of temperatures; they are not true solids.
Chemistry is the driving force between all kinds of innovations. Learn how chemistry plays into innovation as we develop new technologies.
Life depends on chemical reactions to run. Whether you’re making some home brew or sitting in a car with an internal combustion engine, chemical reactions power the world. Sometimes, though, they can cause unexpected health issues.