Metallic radius or Crystal radius:

Metallic radius or Crystal radius:

(1) The term crystal radius is used to denote the size of atoms in metal.

(2) Metal atoms are closely packed spheres in metallic crystal. The metal atoms are supposed to touch one another in crystal.

(3) Metallic radius is defined as one half the distances between the centres of the nuclei of two atoms in a metallic crystal.

(4) Metallic radius is determined by X-ray diffraction method.

(5) Metallic radii are about 10 to 15 % higher than the single bond covalent raddi of those elements. Thus single bond covalent radius is smaller than the metallic radius due to the no overlapping of atomic orbital in metallic bond.

Vander Waal’s radius > Metallic radius > Covalent radius

(6) For the simplicity the term atomic radius is used for covalent radius as well as metallic radius depending on whether the element is a non-metal or metal. However, the atomic radii of inert gases are expressed in the terms of Vander Waal’s radii.

(7) Metallic radius is inversely proportional to the metallic bond strength.

(8) More metallic radius –loose crystal packing-less bond strength. (BCC)

(9) Less metallic radius –Tight crystal packing (FCC) - high bond strength.(HCP)

(10) For non-metal, atomic radius means covalent radius.

(11) For metal, atomic radius means metallic radius.

(12) For inert gases, atomic radius means Vander Waal’s radius.

Vander Waal’s radius or Collision radius:

Related Questions:

(1) What are the Amphoteric metals ? gives Examples.

(2) Name of total metalloids present in periodic table ?

(3) Total numbers of elements which are liquid at normal temperature is ?

(4) What is Mendeleev's periodic table ? give important features and draw back of Mendeleev's table.

(5) What is atomic volume ? and what is periodicity of atomic volume in groups and periods ?

(6) Why there are 2, 8 and 8 elements in first, second and third periodic of periods table respectively ? Explain.

(7) In alkali metal group which is the strongest reducing agent in aqueous solution and why?

(8) The electron affinity of sulphur is greater than oxygen. Why?

(9) The first ionization energy of carbon atom is greater than that of boron atom, whereas reverse is true for the second ionization energy. Explain.

(10) The electronegativities of B, Al, Ga are 2.0, 1.5, 1.6 respectively. The trend is not regular. Explain.

(11) Li2CO3 decomposes on heating but other alkali metal carbonates don’t. Explain.

(12) Of all noble metals, gold has got a relatively high electron affinity. Explain.

(13) Ionization energy of Boron is smaller than Beryllium even though effective nuclear charge is higher?

(14) What are the increasing order of ioni radii of first group elements in water ?

(15) What are the increasing order of molar conductivity of first group elements in water ?