No bond is completely ionic, and some supposedly 'ionic' compounds, especially of the transition metals, are particularly covalent in character. In general, ionic radius decreases with increasing positive charge and increases with increasing negative charge.Īn 'anomalous' ionic radius in a crystal is often a sign of significant covalent character in the bonding. Ionic size (for the same ion) also increases with increasing coordination number, and an ion in a high-spin state will be larger than the same ion in a low-spin state. As with other types of atomic radius, ionic radii increase on descending a group. Nevertheless, ionic radius values are sufficiently transferable to allow periodic trends to be recognized. The ionic radius is not a fixed property of a given ion, but varies with coordination number, spin state and other parameters.

Similarly, when an electron is added to an atom, forming an anion, the added electron increases the size of the electron cloud by interelectronic repulsion. N atom loses an electron to form a cation, the other electrons are more attracted to the nucleus, and the radius of the ion gets smaller. When aause the greater covalent character of the bonds in AgCl and AgBr reduces the bond length and hence the apparent ionic radius of Ag +, an effect which is not present in the halides of the more electropositive sodium, nor in silver fluoride in which the fluoride ion is relatively unpolarizable. Ions may be larger or smaller than the neutral atom, depending on the ion's electric charge. The neutral atoms are colored gray, cations red, and anions blue.

Radius vs steel faith