An angstrom is a unit of wavelength that is equal to 0.1 
(one tenth) of a nanometer. A nanometer is a very tiny 
unit of length equal to one billionth of a meter. A meter is 
approximately 39 inches.  Thus, an angrstom is one ten 
billionth of a meter. Angstroms are used to express the 
size of atoms (such as their arrangement in crystals), the 
size of molecules, the lengths of bonds between 
chemicals, and the length of microscopic organisms.  An 
atom is the smallest part of a substance that can exist 
alone or in combination with something else. A molecule 
is a combination of atoms. 
 
Angstrom is also used to describe the size of electromagnetic radiation waves and the 
size of parts that make up integrated circuits (types of electronic circuits). 
Electromagnetic radiation is a form of energy absorbed and released by electrically 
charged particles, which behave like waves as they travel through space.  The human 
eye can detect wavelengths between four and seven thousand angstroms. 
Angstrom is often abbreviated as "A" with a small circle (known as a ring diacritic) above 
the tip of the A. This is shown in the picture above. Angstrom was named after Anders 
Jonas Angstrom, a Swedish physicist who lived from 1814-1874. The angstrom is a 
widely recognized unit of measurement but is not part of the official International System 
of Units (SI). Angstrom is also known as angstrom unit.