Chemical Properties of Group 14 Elements

Group 14 of the periodic table, also known as carbon group elements, comprises six elements. These elements are carbon (C ), silicon (Si), germanium (Ge), tin (Sn), lead (Pb) and flerovium (Fl). Other than germanium and flerovium (which is artificially produced), all these elements can be found in our daily lives. 

These elements can be found in the form of their compounds. Silicon is abundantly present on the earth’s crust. Carbon is known to have an infinite number of compounds that can be found all around us in several forms.

Objectives and Functions

Structure of the group 14 elements

The P-subshell has three degenerate p orbitals, and each orbital can have two electrons. There are, overall, six groups that belong to the p-block elements. They have a tendency to lose one electron and have shiny exteriors. Most elements of the p subshell are good conductors of heat and electricity. 

Gallium can even melt in our hands. Silicon is used as an important component in the making of glass. Silicon is one of the most essential metalloids from the p-block group of elements. 

Electronic configuration

The general electronic configuration for elements of group 14 is ns2np2. 

The outermost p orbitals for these elements can contain 2 electrons. All elements of group 14 have four electrons in their outermost shell; hence, their valency is four. They engage in bond formation to achieve their octet configuration. 

Oxidation and inner pair effect

The general oxidation state for elements of group 14 is +4 and +2. They have a tendency to form +2 ions, and this increases as we move further down the group. This happens because of a phenomenon known as the inner pair effect. This is because of the absence of s-orbitals during bond formation because of insufficient shielding of the intervening electrons. 

Electrons can be found in the d and f orbitals for elements such as tin and lead. As d and f orbitals have poor shielding abilities, the nuclear charge attracts the s orbital towards the nucleus. Thus, the s orbital is hesitant towards the bond formation, and only the electrons from the p orbitals can engage in bond formation. This is the reason why Pb+2 is a very good oxidising agent. 

Anomalous behaviour of carbon

Despite belonging to the same group, one can observe many differences in the structure and nature of carbon in group 14. Carbon has a smaller atomic size, high electronegativity and high ionisation enthalpy. In addition to this, carbon also lacks a d orbital in its valence shell. 

Chemical properties of elements belonging to group 14

• Covalent radii: the radii for group 14 elements is smaller than group 13 elements. There is an increase in effective nuclear charge, which causes their radii to be smaller. However, one can observe that the increase in radius for Silicon when compared to carbon is significant. This is because of the poor shielding effect of d and f orbitals, causing an increase in effective nuclear charge. 

• Ionisation enthalpy: Group 14 elements have higher ionisation enthalpy than group 13 elements. This is because of their physical size. The ionisation enthalpy decreases as we go down the group. There is a very sharp decrease from carbon to silicon, and then the decrease gets nominal. 

• Due to effective shielding of the d and f orbitals, Lead has a higher ionisation enthalpy than Tin. 

Electronegativity

Due to their comparatively smaller size, the elements of group 14 have more electronegativity than elements from group 13. However, the electronegativity values from silicon to lead are nearly the same. 

Physical properties of group 14 elements

• Metallic character: Because of their smaller size and high ionisation enthalpy, elements from group 14 tend to be less electropositive than elements from group 13. The metallic nature of elements increases as we go down this group. Sn and Pb are known as soft metals, and they tend to have lower melting points, whereas C and Si are nonmetals, and Ge is a common metalloid. 

• Melting and boiling points: Carbon, silicon and germanium have extremely high melting and boiling points because of their stable structures. The inner pair effect causes tin and lead to have lower boiling points as they can form only two bonds instead of four. 

• All the elements from group 14 have a diamond-like layered structure and are very stable in nature. The stable structures can be broken at very high melting points. 

• As the size of the atoms increase, the melting point decreases as we go down the group. This is because the M-M bonds are reduced. Tin and lead are metals, and hence, their melting points are comparatively lower than the others. 

• Four covalent compounds: Covalent compounds are those compounds whose four electrons from the valence shell participate in bond formation. This property is present in most elements from group 14. 

• Density: The density of elements rises as the atomic number increases because of the increase in mass per unit of volume as we go down the group. 

Conclusion

Group 14 of the periodic elements comprises six elements. Their metallic nature increases as we go down the group; however, silicon and carbon are non-metals, and germanium is a metalloid, whereas lead and tin are metals from the group. They have many unique properties because of the formation of