The common name for ethyne is acetylene. Draw a dot diagram and a line drawing for this compound, and indicate whether it is more or less unsaturated than ethene.

The molecular formula of a compound is a concise way of expressing information about the atoms that constitute a particular chemical compound. It uses chemical element symbols from the periodic table followed by numeric subscripts to indicate the number of each type of atom present. For instance, the molecular formula for water is H₂O, which indicates that each molecule of water is comprised of two hydrogen atoms (H) and one oxygen atom (O).

In the context of the exercise, the molecule of interest is ethyne, also known as acetylene. Its molecular formula is C₂H₂, meaning that each molecule of ethyne consists of two carbon atoms and two hydrogen atoms. Understanding the molecular formula is essential in further determining the structure of the compound and its chemical properties, such as unsaturation, which will be discussed later.

While the molecular formula gives the number of each type of atom, the structural formula provides insight into how these atoms are connected within the molecule. The structural formula can depict the spatial arrangement of atoms and the connectivity between them, which is crucial for understanding chemical reactions and properties.

For ethyne, the structural formula can be illustrated as H-C≡C-H. The triple line between the carbon atoms signifies a triple bond, which is a strong, stable, and energetic bond consistent with the behavior of ethyne. This visual representation is vital for chemists to predict the geometry of the molecule and its reactivity with other substances.

Unsaturation in organic chemistry refers to the presence of multiple bonds between carbon atoms within organic molecules—double bonds, triple bonds—or rings. These unsaturated bonds are more reactive than single bonds, and they drastically influence the physical and chemical characteristics of a compound.

Unsaturated hydrocarbons such as ethyne and ethene are categorized based on their degree of unsaturation. The unsaturation level can be compared by counting the number of hydrogen atoms that would be needed to saturate all the multiple bonds in the compound. In the given exercise, ethyne (C₂H₂) is more unsaturated than ethene (C₂H₄) because ethyne has a triple bond, which represents higher unsaturation compared to the double bond in ethene. This concept of unsaturation is a cornerstone in organic synthesis and molecular characterization.

Carbon-carbon triple bonds are a feature of alkynes, a class of hydrocarbons characterized by having at least one pair of carbon atoms connected by a triple bond. The triple bond itself consists of one sigma (σ) bond and two pi (π) bonds.

The carbon atoms involved in a triple bond display linear geometry, influencing the overall shape of the molecule. Compounds with carbon-carbon triple bonds are quite reactive due to the high energy of the π bonds, which are more exposed to reactants than the σ bond. Ethyne's reactivity can be attributed to its carbon-carbon triple bond, an important aspect considered when predicting reactions that involve acetylene in industrial applications and organic synthesis.