Question

Draw the structures for two examples of saturated hydrocarbons. To how many other atoms is each carbon atom in a saturated hydrocarbon bonded?

Short answer

Two examples of saturated hydrocarbons are methane (CH4) and ethane (C2H6). The structure of methane is a central carbon atom bonded to four hydrogen atoms, forming a tetrahedral shape. In ethane, two carbon atoms are connected by a single bond, and each carbon atom is bonded to three hydrogen atoms, creating two tetrahedrons sharing one side. In both cases, each carbon atom in these saturated hydrocarbons is bonded to four other atoms.

Step-by-step solution

Example 1: Methane (CH4)

Methane is a simple saturated hydrocarbon with only one carbon atom and four hydrogen atoms. Its chemical formula is CH4. To draw its structure, follow these steps: 1. Draw the carbon atom in the center with a single bond coming from each of the four sides. 2. Attach a hydrogen atom to each of the single bonds surrounding the central carbon atom. 3. The structure should look like a tetrahedron, with the carbon atom at the center and the hydrogen atoms surrounding it. In methane, each carbon atom is bonded to four hydrogen atoms.

Example 2: Ethane (C2H6)

Ethane is a saturated hydrocarbon with two carbon atoms and six hydrogen atoms. Its chemical formula is C2H6. To draw its structure, follow these steps: 1. Draw two carbon atoms in a horizontal line, with a single bond connecting them. 2. Attach three hydrogen atoms to each carbon atom using single bonds, so that the carbon atoms are surrounded by the hydrogen atoms. 3. The structure should look like two tetrahedrons sharing one side. In ethane, each carbon atom is bonded to three hydrogen atoms and one other carbon atom, making a total of four bonds to other atoms. To summarize: In saturated hydrocarbons, each carbon atom is bonded to four other atoms. The number and arrangement of these bonds can vary depending on the hydrocarbon, but the total number of bonds is four.

Key concepts

Chemical Structure of Saturated Hydrocarbons

Understanding the chemical structure of saturated hydrocarbons is crucial in the study of organic chemistry. Saturated hydrocarbons, also known as alkanes, are compounds that consist solely of carbon (C) and hydrogen (H) atoms with single bonds between the carbon atoms. The term 'saturated' implies that each carbon atom is fully bonded with hydrogen atoms, with no capacity to bond with more atoms.

Saturated hydrocarbons are characterized by their general formula (C_nH_{2n+2}), which indicates that for every 'n' number of carbon atoms, there should be '2n + 2' hydrogen atoms. For instance, the simplest alkane, methane (CH_4), has one carbon atom bonded to four hydrogen atoms. The structure of methane can be visualized as a central carbon atom with four single bonds extending to hydrogen atoms, forming a tetrahedral molecular geometry.

In saturated hydrocarbons like ethane (C_2H_6), every carbon atom continues to obey the rule of forming four bonds, resulting in a chain of carbon atoms each bonded to sufficient hydrogen atoms to maintain the saturation. This chain-like structure showcases how organic molecules can expand and vary in complexity while still adhering to their fundamental bonding rules.

Molecular Geometry in Saturated Hydrocarbons

The molecular geometry of saturated hydrocarbons is governed by the spatial arrangement of the atoms and the bonds within the molecule. A fundamental principle in understanding molecular geometry is the Valence Shell Electron Pair Repulsion (VSEPR) theory, which explains the shapes of molecules based on the repulsion between electron pairs in the valence shell of atoms.

For saturated hydrocarbons, the central carbon atoms form sp³ hybrid orbitals that direct the shape of their bonds into a tetrahedral geometry; this means that the bonded hydrogen atoms are spaced as far apart as possible, resulting in bond angles of approximately 109.5 degrees.

Evidence of Tetrahedral Geometry

For methane, the tetrahedral shape is a consequence of the four sp³ hybrid orbitals aligning themselves symmetrically around the central carbon. In ethane, each carbon atom also adopts this tetrahedral structure, though shared between the two carbon atoms the molecule exhibits a staggered conformation to minimize repulsion between the hydrogen atoms attached to neighboring carbons.

The learnings from this molecular geometry are not only pivotal for visualizing the structure but also for predicting the physical and chemical properties of various organic compounds.

Introduction to Organic Chemistry

Organic chemistry is a rich and dynamic field of study concerned with the structure, properties, composition, reactions, and synthesis of organic compounds, which are defined primarily by their carbon-based structure. Saturated hydrocarbons serve as the backbone for the myriad molecules that makeup organic chemistry.

Significance of Carbon
One of the most extraordinary attributes of carbon is its ability to create long chains and rings by bonding with other carbon atoms – a property known as catenation. This leads to an immense variety of compounds that are possible with even a small number of carbon atoms.

Bonding and Reactions
Organic molecules can engage in many types of reactions, but the foundational understanding comes from knowing how these molecules are constructed. As seen in the example of methane (CH_4) and ethane (C_2H_6), saturated hydrocarbons contain only single bonds between carbons and are known for their relative chemical stability.

The study of organic chemistry extends beyond just hydrocarbons, encompassing functional groups such as alcohols, ketones, and acids, each imparting different chemical behaviors to the carbon skeleton. Through organic chemistry, we gain insights into how molecules interact, how drugs are designed, and how biochemical processes occur in living organisms, making it an essential discipline in both the scientific and practical domains.