Ionic Radius of Elements: We call an atom as an ion if it loses or gains an electron. If the ion is formed by loss of one or more electron we call as cation( positive ion). If an atom gains an electron from another atom we called as an anion (negatively ion).
The distance from the centre of nucleus up to which (proton) nuclear charge exerts influence on electrons.
Ionic radius is the distance between the nucleus and outermost shell of an ion.Some practical methods are present to calculate the radius of the ion. The values by scientist Pauling are most acceptable. It is quite easy to determine the inter-nuclear distance between the two opposite charges(say Na+ and CL— ions) with the help of X-ray study.
Characteristics related with Ionic Radius of Elements
1.The radius of cation is always smaller than that of the atom. We know that when atom loss one or more electrons, atom changes to a cation. In most of the cases, electron present in the valence shell of an atom is completely removed. As a result, nuclear charge (proton) become more than that of electrons.So, therefore there will be a great hold of positive charge having the influence on electrons.
2. The radius of the anion is always greater than that of the atom. When atom gains one or more electrons, atom changes to an anion. Since the nuclear charge remains unchanged, the number of electrons in an anion experience less attraction towards the proton compared with the atom. Therefore, an Ionic radius is larger than that of the corresponding atom.
Isoelectronic species In Ionic Radius of Elements
Isoelectronic species: Different atoms have the same number of electrons.Atoms have the different magnitude of nuclear charge(proton) in iso-electronic.
A. Among the isoelectronic species, the size of the ion is always more than that of cation.
B. The size of the ion increases with the increase of negatively charged.
C. The size of cation decreases with the increase of positively charged.
This is whole about the article Ionic Radius of Elements.