Group 14 Elements (Carbon Family)

What Are Group 14 Elements?

The group 14 elements are the second group in the p-block of the periodic table. It is also called the carbon group. The members of this group are listed below:

• Carbon (C)
• Silicon (Si)
• Germanium (Ge)
• Tin (Sn)
• Lead (Pb)
• Flerovium (Fl)

Table of Contents

• Electronic Configuration
• Oxidation States
• Anomalous Behaviour of Carbon
• Chemical Properties
• Physical Properties
• Compounds Formed by Group 14 Elements

Electronic Configuration of Group 14 Elements

The group 14 elements have a general electronic configuration of ns²np². These elements have 2 electrons in the outermost p orbitals. The electronic configuration of these elements is shown below:

As all the elements in group 14 have 4 electrons in the outermost shell, the valency of group 14 elements is 4. They use these electrons in the bond formation in order to obtain an octet configuration.

Oxidation States and Inert Pair Effect of Group 14 Elements

The general oxidation states exhibited by the group 14 elements are +4 and +2.

As we go down the group, the tendency to form +2 ion increases. This is due to the inert pair effect. This effect is exhibited by p-block elements.

This can be explained using the inert pair effect. It is the non-participation of the s-orbital during bonding due to the poor shielding of the intervening electrons.

⇒ Check: List of all periodic table elements

For elements like Sn and Pb, d and f orbitals are filled with electrons. Since the shielding ability of the d and f orbitals is very poor, the nuclear charge that seeps through attracts the s orbital closer to the nucleus. This makes the s orbital reluctant to bond, and thereby, only the p electrons are involved in bonding.

Therefore, Pb4+ is a very good oxidising agent.

⇒ Also Read:

• Silicon
• Germanium
• Tin
• Lead
• Flerovium

Anomalous Behaviour of Carbon

Carbon exhibits different behaviour from the rest of the group due to,

• Small size
• High electronegativity
• High ionization enthalpy
• Absence of d-orbital in the valance shell

Chemical Properties of Group 14 Elements

Covalent Radii

The radii of group 14 elements are lesser than that of group 13 elements. This can be explained by the increase in the effective nuclear charge.

The increase in the radii from C to Si is considerable, after which the increase in the radii is less. This can be attributed to the poor shielding of d and f orbitals, which increase the effective nuclear charge, thereby making the radii small.

Ionization Enthalpy

The ionization energy of group 14 elements is greater than that of group 13 elements. This can be attributed to size.

Down the group, the ionization enthalpy decreases. There is a sharp decrease from C to Si, after which the decrease is nominal.

The order is as follows, C > Si > Ge > Pb >Sn

Here, Pb has a greater ionization enthalpy than Sn due to the ineffective shielding of d and f orbitals.

⇒ Check: s-block elements

Physical Properties of Group 14 Elements

Metallic Character

Group 14 elements are less electropositive than group 13 owing to their small size and high ionization enthalpy.

Down the group, the metallic character increases. C and Si are non-metals, Ge is a metalloid, and Sn and Pb are soft metals with low melting points.

Melting and Boiling Points

The melting and boiling point of carbon, silicon, and germanium is significantly high because they have a very stable solid structure. Sn and Pb have a lower melting point because only two bonds are formed instead of four due to the inert pair effect.

The melting point of carbon is extremely high. All the elements of group-14 possess a diamond-type lattice structure which is highly stable in nature. The process of melting results in the breakage of these highly stable lattice structures.

Down the group, the melting point decreases as the M-M bonds are reduced as the size of the atoms increases. Since tin and lead are metals, the melting points of these elements are much lower.

Four Covalent Compounds

Four covalent compounds are compounds in which the four electrons in the valence shell play an active role in bonding. Most of the group 14 element possesses this property.

Compounds Formed by Group 14 Elements

Hydrides of Group 14

All the elements of group 14 form hydrides. Carbon forms hydrides extensively due to their ability to catenate. The hydrides of carbon are categorised as given below:

• Alkanes (paraffins): General formula: C_nH_2n+2
• Alkenes (olefins): General formula: CnH2n
• Alkynes (Acetylenes): General formula: C_nH_2n-2
• Aromatic compounds
• Silicon forms hydrides having the general formula Si_nH_2n+2 and is called silanes.
• Germanium forms hydrides of the form Ge_nH_2n+2, where n_max=5 and is called germanes.
• Tin forms SnH₄ and is called stannane. It is much less stable.

Oxides of Group 14

Group 14 elements form oxides of the type MO and MO₂. Lead also form an oxide Pb₃O₄ which is a mixed oxide of PbO and PbO₂. Among the monoxides, CO is neutral, GeO is basic, and SnO and PbO are amphoteric.

In CO₂, C is sp hybridized. It is different from SiO_2, in which Si is sp³ hybridized. In SiO₂, each O atom is bonded to two Si bonds. This gives rise to a three-dimensional structure for SiO₂. This also attests to the high melting point of SiO₂. Get more details at byjus.com/jee/hybridization.

Among the dioxides, the acidic character decreases down the group. CO₂ is the most acidic, and PbO₂ is the most basic among the dioxides.

⇒ Also Read: Allotropes of Carbon

Halides of Group 14

They form tetrahalides of the form MX4. The central atom is sp³ hybridized and assumes a tetrahedral shape.

Note: Elements below C have empty d-orbitals, with which they can exhibit back bonding with the halogens (pπ-dπ).

Carbon does not form dihalides. The dihalides are sp² hybridized and have a bent shape.

⇒ Also Read: 

• F-Block Elements
• D-Block Elements

• Introduction to Organic Chemistry