Electron diffraction
When we allow beam of electrons to interact with atoms or molecules, because of the wave properties of the electrons, they get diffracted. The diffraction of a beam of electrons by the surface of a nickel single crystal was used by Davission and Germer to demonstrate that electrons have wave properties. Electron diffraction finds use to study molecular structure, especially in the gas phase and the investigation of surfaces.

Electronegativity
It is the ability of an atom to attract the share pair of electrons towards itself. Fluorine is the most electronegative element.

Electronic band spectra
Molecular spectra occurring in ultraviolet or visible regions of spectrum, studied by absorption or emission.

Elinvar
Trade name for a nickel¾ chromium steel containing about 36% nickel, 12% chromium, and smaller proportions of tungsten an manganese. Its elasticity does not vary with temperature and it is therefore used to make hairspring for watches.

Elutriation
The method of separating a material into fractions of various sizes by permitting it to settle against upward moving stream of fluid, generally air or water.