Princeton's WordNet(0.00 / 0 votes)Rate this definition: geological time, geologic time(noun) the time of the physical formation and development of the earth (especially prior to human history)
Ionic radius, r ion, is the radius of an atom's ion.Although neither atoms nor ions have sharp boundaries, they are sometimes treated as if they were hard spheres with radii such that the sum of ionic radii of the cation and anion gives the distance between the ions in a crystal lattice.herefore, the distance between the Na + and Cl â ions is half of 564.02 pm, which is 282.01 pm. However, although X-ray crystallography gives the distance between ions, it doesn't indicate where the boundary is between those ions, so it doesn't directly give ionic radii.
1 An ionic solid is made up of positive ions (cations) and negative ions (anions) held together by electrostatic forces in a rigid array or lattice. 2  Ionic bonding refers to the electrostatic attraction between cations and anions.3  The physical properties of ionic compounds are:4  High melting and boiling points. An ionic solid is made up of positive ions (cations) and negative ions (anions) held together by electrostatic forces in a rigid array or lattice. 2  Ionic bonding refers to the electrostatic attraction between cations and anions.