Question

What is the hybridization of carbon in alkanes?

Short answer

Answer: The hybridization of carbon in alkanes is sp^3.

Step-by-step solution

Identify the general formula and structure of alkanes

The general formula for alkanes is CnH2n+2, where n is the number of carbon atoms. Alkanes are saturated hydrocarbons, meaning that they only contain single bonds between the carbon and hydrogen atoms.

Determine the number of sigma bonds and lone pairs around the carbon atom

Each carbon atom in alkane forms single bonds with other carbon atoms and hydrogen atoms. A single bond consists of one sigma bond. In alkanes, each carbon atom will form four sigma bonds. The carbon atom in alkane has no lone pairs of electrons, as all its valence electrons are used to form sigma bonds.

Determine the hybridization of the carbon atom based on its bonding

To determine the hybridization of the carbon atom in alkanes, we can count the number of sigma bonds and lone pairs around it. Since the carbon atom forms four sigma bonds and has no lone pairs, its hybridization will be sp^3. This is because the carbon atom's four valence electrons (from 2s and 2p orbitals) combine to form four equivalent sp^3 hybrid orbitals, which then form sigma bonds with other atoms. So, the hybridization of carbon in alkanes is sp^3.

Key concepts

Saturated Hydrocarbons

When we talk about saturated hydrocarbons, we're referring to a class of compounds that feature only single bonds between the carbon (C) and hydrogen (H) atoms. This is important because the structure of these hydrocarbons allows them to be "saturated" with hydrogen. Since they have no room for additional hydrogen atoms to bond because they are fully saturated with single bonds, that's how they get their name.

Alkanes, which are the simplest type of hydrocarbons, fall into the category of saturated hydrocarbons. Their chemical formula is CnH2n+2, meaning for every n carbon atoms, there are 2n+2 hydrogen atoms. Alkanes such as methane (CH4), ethane (C2H6), and propane (C3H8) are typical examples. What makes them unique is their ability to resist reactions like addition reactions, which is not the case with unsaturated hydrocarbons that have double or triple bonds. This stability is why saturated hydrocarbons are also referred to as paraffins.

Sigma Bonds

In the world of chemistry, bonds are the glue that holds atoms together. Sigma bonds (\(\sigma\)-bonds) are the strongest type of covalent chemical bond. They occur when two orbitals overlap head-on, allowing for free rotation around the bond axis. This overlap usually involves two 's' orbitals or one 's' and one 'p' orbital.

In alkanes, each carbon atom forms sigma bonds:

• With other carbon atoms
• With hydrogen atoms

Each single bond in an alkane is a sigma bond, meaning each carbon atom in an alkane typically has four sigma bonds. This arrangement allows for a very stable structure. Additionally, the presence of sigma bonds makes alkanes less reactive than alkenes and alkynes, which have multiple bond types like pi (\(\pi\)) bonds. These sigma bonds are responsible for many of the alkanes' physical properties, such as lower density and higher boiling and melting points.

sp3 Hybridization

Hybridization is a concept in chemistry that describes the mixing of atomic orbitals to form new hybrid orbitals. In the case of alkanes, carbon atoms undergo sp3 hybridization. This is because carbon needs to form four equivalent bonds, and its electron configuration of 1s^2 2s^2 2p^2 can be reshaped for the task.

Through hybridization:

• One 's' orbital
• Three 'p' orbitals

combine to form four sp3 hybrid orbitals, all having equal energy and shape. These sp3 orbitals form the sigma bonds with hydrogen atoms or other carbon atoms. Forming a tetrahedral geometry, each bond angle is about 109.5 degrees. This geometry minimizes repulsions between the electron pair bonds leading to a stable arrangement. The concept of sp3 hybridization is key to understanding the structure and stability of alkanes, making them distinguished in organic chemistry.