solid object is in the
states of
matter characterized by resistance to
deformation and
changes of
volume. In other words, it has high values both
of
Young's modulus and of
shear modulus;
this contrasts e.g. with a
liquid, which has a low shear modulus. At the
microscopic scale, a solid has these properties :
- The atoms or molecules that
compose the solid are packed closely together.
- These constituent elements have fixed positions in space
relative to each other. This accounts for the solid's rigidity. In
mineralogy and crystallography, a crystal structure is a unique
arrangement of atoms in a crystal. A crystal structure is composed of a
unit cell, a set of atoms arranged in a particular way; which is
periodically repeated in three dimensions on a lattice. The spacing
between unit cells in various directions is called its lattice
parameters. The symmetry properties of the crystal are embodied in its
space group. A crystal's structure and symmetry play a role in
determining many of its properties, such as cleavage, electronic band structure, and
optical properties.
- If sufficient force is applied, either of these properties can be
disrupted, causing permanent deformation.
- Because solids have thermal
energy, their atoms vibrate. However, this movement is very
small, and cannot be observed or detected under ordinary circumstances.
In a solid, the particles are vibrating in place. A solid doesn't flow.
The branch of physics that deals with solids is called solid-state physics, and is a type of condensed matter
physics. Materials
science is primarily concerned with properties of solids such
as strength and phase
transformations. It overlaps strongly with solid-state physics. Solid-state chemistry overlaps both of these
fields, but is especially concerned with the synthesis of novel
materials.
The lightest known solids are aerogels. The lightest
aerogel produced has a density of 1.9 mg/cm³ or 1.9 kg/m³
(1/530 the density of
water