atomic radius.pptx

It is about atoimc radius .

1. 6.2. ATOMIC SIZES ATOMIC RADII, IONIC RADII AND COVALENT RADII. The size of an atom is very important because many physical and chemical properties are related to it. Atoms are assumed to be spherical. That is why, we report the various types of radii to guess their sizes For this reason, the sizes of atoms are expressed in terms of atomic radii, ionic radii and covalent radii, etc,. depending upon the type of the compound used for its measurement. The atomic radius means the average distance between the nucleus of the atom and its outermost electronic shell. The radius of an atom cannot be determined precisely due to the following reasons. ( i ) There is no sharp boundary of an atom. The probability of inding an electron never becomes exactly zero even at large distances from the nucleus. (ii) The electronic probability distribution is afected by neighbouring atoms. For this reason,the size of an atom may change from one compound to another. Atomic radii can be determined, by measuring the distances between the centres of adjacent atoms with the help of X-rays or by spectroscopic measurements. Atomic radii of elements of the periodic table in pm are shown in Table (6.2).