Bonding in Carbon: The Covalent bond, Electron dot structure, Physical properties of organic compounds, Allotropes of Carbon.
carbon atom loses four of its valence electrons, a huge amount of energy is involved. C4+ ion hence formed will be highly unstable due to the presence of six protons and two electrons.
If the carbon atom gains four electrons to achieve the nearest electronic configuration of the noble gas, Ne, C4− ion will be formed. But again, a huge amount of energy is required. Moreover, in C4+ ion it is difficult for 6 protons to hold 10 electrons. Hence, to satisfy its tetravalency, carbon shares all four of its valence electrons and forms covalent bonds.
Covalent Bond: The atomic number of carbon is 6. Its electronic configuration is 2, 4. It requires, 4 electrons to achieve the inert gas electronic configuration. But carbon cannot form an ionic bond.
Types of Covalent Bond:
- Single Covalent Bond: When a single pair of electrons are shared between two atoms in a molecule. For example; F2, Cl2, H2 etc.
- Double Covalent Bond: When two pairs of electrons are shared between two atoms in a molecule. For example; O2, CO2 etc.
- Triple Covalent Bond: When three pairs of electrons are shared between two atoms in a molecule. For example; N2 etc.
Electron Dot Structure: The electron dot structures provides a picture of bonding in molecules in terms of the shared pairs of electrons and octet rule.
Formation of Hydrogen Molecule: Single bond
Atomic number of Hydrogen = 1
Number of valence electrons = 1
Formation of Oxygen molecule: double bond
Atomic number of Oxygen = 8 [2, 6]
Number of valence electrons = 6
Formation of Nitrogen molecule: triple bond
Atomic number of Nitrogen = 7 (2, 5)
Number of valence electrons = 5
Covalent Bonding in Carbon:
A methane molecule (CH4) is formed when four electrons of carbon are shared with four hydrogen atoms
Atomic number of Carbon = 6 [2, 4]
Number of valence electrons = 4
Atomic number of Hydrogen = 1
Number of valence electrons = 1
Allotropes of Carbon
Allotropy: The phenomenon in which the element exists in two or more different physical states with similar chemical properties are called Allotropy.
Carbon has Three Main Allotropes
- Diamond: In this, carbon, an atom is bonded to four other atoms of carbon forming three-dimensional structures. It is the hardest substance and an insulator. It is used for drilling rocks and cutting. It is also used for making jewellery.
- Graphite: In this, each carbon atom is bonded to three other carbon atoms. It is a good conductor of electricity and used as a lubricant.
- Buckminster Fullerene: It is an allotrope of the carbon-containing cluster of 60 carbon atoms joined together to form spherical molecules. It is dark solid at room temperature.
Hydrocarbons: Compounds of carbon and hydrogen are known as hydrocarbons.
For example; Methane (CH4), Ethane (C2H6), Ethene (C2H4), Ethyne (C2H2) etc.
Saturated Hydrocarbon (Alkanes): General formula is CnH2n+2.
n = number of carbon atoms.
In this, the carbon atoms are connected by only a single bond.
For example; Methane (CH4), Ethane (C2H6) etc.
Unsaturated Hydrocarbons
Alkenes: General formula is CnH2n, where n = number of carbon atoms.
In this, the two carbon atoms are connected by double bond.
Alkynes: General formula is CnH2n-2, where n = number of carbon atoms. In this, the two carbon atoms are connected by triple bond.
