Question

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Answer 1

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Answer 2

1)The shielding effect can be defined as a reduction in the effective nuclear charge on the electron cloud, due to a difference in the attraction forces of the electrons in the nucleus. Shielding is when electrons in the inner electron shells of an atom can shield the outer electrons from the pull of the nucleus.

The nucleus can pull the outer electrons in tighter when the attraction is strong and less tight when the attraction is weakened.

Therefore, the more shielding that occurs, the less attraction there is between the outer electrons and nucleus, so the the further the electrons in the outer shell can spread out. This means the atomic radius will be larger.

2) Metallic radius is defined as one-half of the distance between the two adjacent metal ions in the metallic lattice. This radius depends on the nature of the atom as well as its environment—specifically, on the coordination number (CN), which in turn depends on the temperature and applied pressure. The covalent radius is measured by overlapping of atomic clouds. Due to this the nuclei are pulled together as the electrons are positioned between the nuclei. This contraction of nucleus makes the covalent radius smaller. Metallic radii are measured as the distance between two metal atoms bonded with a single bond. This is very difficult to measure as the metal atoms are in a chunk of metal as positive ions surrounded by a sea of electrons. Thus the metal ions are touching the electrons and are not like overlapping which is the case of covalent radii. Because of this the metallic radii of atoms is greater than the corresponding covalent radii of those metals.