GROUP 12: ZINC, CADMIUM, AND MERCURY
The elements
Group 12 elements contain the electron configurations (n-1)d10ns2 with n=4, 5 and 6 for Zn, Cd and Hg, correspondingly. They are properly a part of the d block but the electrons of the (n-1)d shell are very tightly bound to be concerned directly in chemical bonding, and these elements depict typical post-transition metal behavior. The additional nuclear charge related with filling the d orbitals directed to high ionization energies in comparison with group 2 elements and therefore reduced electropositive character. This is particularly pronounced with mercury that creates few compounds that can be regarded as ionic.
The elements are found in nature like sulfides, particularly ZnS (zinc blende or sphalerite) and HgS (cinnabar). In the crust Overall abundances are low. Zinc is a significant element of life; Cd and Hg are not necessary and are very toxic.
The elements might be obtained through reduction of sulfides or oxides (example ZnO with C). Zinc and cadmium are used for corrosion-resistant coatings. The metals comprise melting and boiling points which are lower than for group 2 elements, particularly with Hg, that is one of two elements (Br being the other) presenting as a liquid at 25°C. Zn and Cd are more reactive than Hg, dissolving within non-oxidizing acids and creating oxide films in air. At room temperature mercury oxidizes but HgO decomposes willingly on heating, a reaction historically significant in the innovation of oxygen. Mercury dissolves several metallic elements to create amalgams that can be helpful reagents (example sodium amalgam like a reducing agent, being much easy to handle than elemental sodium).