Matter

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In science, matter is commonly defined as the substance of which physical objects are composed, not counting the contribution of various energy or force-fields, which are not usually considered to be matter per se (though they may contribute to the mass of objects). Matter constitutes much of the observable universe, although again, light is not ordinarily considered matter. Unfortunately, for scientific purposes, "matter" is somewhat loosely defined. It is normally defined as anything that has mass and takes up space.

A solid object is in the states of matter characterized by resistance to deformation and changes of volume. 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 felt under ordinary conditions.

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 solid is aerogel. The lightest aerogel produced has a density of 1.9 mg/cm³ or 1.9 kg/m³ (1/530 the density of water).

Gas

A gas is a state of matter, consisting of a collection of particles (molecules, atoms, ions, electrons, etc.) without a definite shape or volume that are in more or less random motion.

Physical characteristics

Due to the electronic nature of the aforementioned particles, a "force field" is present throughout the space around them. Interactions between these "force fields" from one particle to the next give rise to the term intermolecular forces. Dependent on distance, these intermolecular forces influence the motion of these particles and hence their thermodynamic properties. It must be noted that at the temperatures and pressures characteristic of many applications, these particles are normally greatly separated. This separation corresponds to a very weak attractive force. As a result, for many applications, this intermolecular force becomes negligible.

A gas also exhibits the following characteristics:

• Relatively low density and viscosity compared to the solid and liquid states of matter.
• Will expand and contract greatly with changes in temperature or pressure, thus the term "compressible".
• Will diffuse readily, spreading apart in order to homogeneously distribute itself throughout any container.

Gas particle movement

The Royal Institution, MIT, Berkeley, Lawrence Livermore National Laboratory,

CalTech, Cambridge, Rutherford Appleton Laboratory, Harwell,

AERE, NSF, Los Alamos, Argonne National Laboratory,

Hope this introduction is helpful as the website build more information will be available.

Email: matter@atomicnrg.com