Electron shell
* make up the electron configuration of an atom
  * have one or more 'electron subshells', or 'sublevels'. These sublevels have two or more orbitals with the same angular momentum quantum number 'l'. Electron shells make up the electron configuration of an atom

### electron:

Backscattered electron
* are an example of elastic scattering
  - high-energy electrons that rebound from the sample surface
* have high energies, up to the beam energy, due to the elastic collisions.
* leave the sample carrying energy without producing X-rays.

Electron affinity
* Electron affinities follow the same pattern.
* decreases down a group because the atomic size increases.
* is a. the energy loss when an electron is removed from an atom b.
* is the energy involved when an anion loses an electron
  - required to attach an electron to a gaseous neutral atom
* measure of how strongly an atom can bind an additional electron.

Free electron
* are able to traverse materials rather readily as in conductors
  - part of normal metabolism but can do enormous damage to all cell components
  - the charge carriers in metals, while ions are the charge carriers in solutions
* is an electron

Photoelectron
* emitted from the inner shells of an atom also behave as outgoing waves.
* released by the photocathode enter a narrow and curved semiconductive channel.

### electron:

Pi electron
* give it a high electrical conductivity.
* refer to a type of bond that occurs between electron orbitals called pi orbitals.
+ Ultraviolet–visible absorption, Chromophores: Light :: Physics
  * Molecules that absorb light at these wavelengths are called chromophores. Chromophores are functional groups of a molecule that absorb light in this UV-Visible region. They are most of the time characterized by delocalized pi electrons. Pi electrons refer to a type of bond that occurs between electron orbitals called pi orbitals. When many of these pi bonds exist in a molecule this allows electrons to be delocalized or spread out across a molecule. An example of this type of molecule is pictured below. These molecules can be used for pH indicators to determine if a solution is acidic or basic. The addition of acid or base disrupts the delocalized pi electrons. This disruption causes a color change.

Unpaired electron
* facilitates other atoms or molecules to bond with it in a chemical reaction.
* give a paramagnetic substance.

### electron:

Valence electron
* are all that are needed to describe bonding.
* are electrons close to the nucleus of the atom
  - involved in the bonding process
* are important in determining how the atom reacts chemically with other atoms
  - how a chemical element reacts with other elements
  - involved in the formation or breaking of bonds
  - only outer energy level electrons
  - responsible for the reactivity of an element
* are the electrons present in the outermost shell of an atom
  - number of electrons of an atom that are involved in a chemical bond
  - outermost electrons in any atom.
  * In chemistry, 'valence electrons' are the electrons in the outside or 'valence' electron shell of an atom. Valence electrons are important in how a chemical element reacts with other elements. The number of valence electrons is also important for determining the group of an element in the Periodic table, because an element's number of valence electron is the same as the number of its group in the periodic table
* is an electron

### electronic card types:

Room key
* are electronic card types.
* are located in hotels
  - motels

### electronic communication:

Data communication
* covers the fast moving dynamic field of electronic communications.
* happen over the Internet.
* is electronic communication
* is the fastest growing area of the telecommunications hardware industry
  - most rapidly expanding area of telecommunications
  - used in many applications of business and in everyday life