Part of genome which changes expression of genome called as mutable loci or sometimes GENES

#Id: 7746

#Unit 1. Structure and Function of Biomolecules

The noble gases are left out of the trends in atomic radii because there is great debate over the experimental values of their atomic radii.

The SI units for measuring atomic radii are the nanometer (nm) and the picometer (pm). 1 nm = 1 X 109 m; 1 pm = 1 X 10-12 m.

#Id: 7747

#Unit 1. Structure and Function of Biomolecules

Size of atom or atomic radii can be estimated by effective nuclear charge

#Id: 7748

#Unit 1. Structure and Function of Biomolecules

Zeff=Z –S

Chlorine would have a Z value of 17 (the atomic number of Chlorine). Continuing to use Chlorine as an example, the 10 inner electrons (S) would screen out the positive charge of ten protons. Therefore there would be and effective nuclear charge of 17-10 or +7.

#Id: 7749

#Unit 1. Structure and Function of Biomolecules

#Id: 7750

#Unit 1. Structure and Function of Biomolecules

The greater the effective nuclear charge the more tightly an electron is held in by the nucleus because there is less electron shield between the valence electrons and the nucleus, and so, the smaller the radius.

#Id: 7751

#Unit 1. Structure and Function of Biomolecules

Ranks the following in increasing atomic radius

S, Mg, Al

S: 16-10 +6

Mg: 12-10 = +2

Al: 13-10 +3

So: S < AlMg