Which of the following are organic compounds? (a) \(\mathrm{CH}_{3} \mathrm{CH}_{3}\) (b) \(\mathrm{NH}_{3}\) (c) \(\mathrm{CH}_{3} \mathrm{SCH}_{3}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) (e) \(\mathrm{Mg}(\mathrm{OH})_{2}\)

Organic compounds are the basis of all life on Earth, exhibiting a vast array of structures and functions. The primary characteristic that distinguishes organic compounds from inorganic ones is the presence of carbon atoms. However, it's not just the presence of carbon that makes a compound organic; it's also the way these atoms are bonded and structured.

Typically, organic compounds have carbon-hydrogen (C-H) bonds, but they can also include other elements such as nitrogen, oxygen, sulfur, and phosphorus. These compounds are found in all living organisms, where they participate in crucial biological processes. They are also synthetically produced for various industrial and pharmaceutical applications. Another distinct feature is that organic compounds can form long chains and rings through covalent bonding, creating complex structures like proteins and DNA.

Key Characteristics of Organic Compounds:

• Contains carbon (C) atoms.
• Usually has one or more hydrogen (H) atoms.
• May contain oxygen (O), nitrogen (N), sulfur (S), phosphorus (P), etc.
• Forms long chains, branched structures, or rings through covalent bonding.
• Exists naturally in living organisms and can be synthesized artificially.

To determine if a molecule is organic, one must examine its structure and composition. A key step is ensuring the molecule contains carbon. For chemistry students and professionals, identifying organic molecules is a fundamental skill that hinges on understanding typical organic structures and functional groups.

A functional group is a specific group of atoms within a molecule that is responsible for the characteristic reactions of that compound. Familiarity with common functional groups like hydroxyl (OH), carboxyl (COOH), and amino (NH2) groups, among others, is crucial. For instance, alcohols are recognized by the presence of a hydroxyl group bonded to a carbon atom.

Steps for Identifying Organic Molecules:

• Confirm the presence of carbon atoms.
• Look for hydrogen atoms forming C-H bonds with carbon.
• Identify functional groups that are hallmarks of organic compounds.
• Assess the overall arrangement of atoms and note the presence of complex structures.

Carbon-based compounds, also known as organic compounds, form the skeleton of organic chemistry. Carbon is a unique element that has the ability to form four stable covalent bonds with other atoms, allowing for a diversity of compounds with varying properties and complexities.

The versatility of carbon allows it to form long chains and rings that can further be decorated with functional groups, leading to substances ranging from simple gasses like methane to complex biomolecules like nucleic acids. The study of carbon-based compounds encompasses not only their structural description but also the exploration of chemical reactions and the synthesis of new compounds with desired properties.

Carbon's ability to catenate, or link together with other carbon atoms, is the foundation of the vast diversity of organic chemistry. This ability means the possibilities for new molecules and materials are virtually endless, driving research and innovation in areas like materials science, biochemistry, and pharmacology.