Homologous series is a term used in organic chemistry to describe a group of compounds with similar chemical properties and structural characteristics. The word is spelled using the International Phonetic Alphabet (IPA) as [həˈmɒləɡəs ˈsɪəriːz]. The phonetic transcription indicates that the first syllable is pronounced as "huh", the second syllable as "mol", and the third syllable as "uh-gus." The fourth syllable, "ser-eez", is pronounced with a long "e" sound at the end. Proper spelling and pronunciation of scientific terminology is essential for clear communication and research.
A homologous series refers to a group of organic compounds that possess similar chemical properties, as well as a predictable pattern in their molecular structure. These compounds have a common functional group and display a sequential increase in the number of carbon atoms in their chemical structure. The members of a homologous series share a general formula, which allows for the determination of the molecular formula of any compound in the series.
Each compound within a homologous series has similar physical properties, such as boiling points, melting points, and solubilities, that gradually change according to the increase in molecular size. Despite these similarities, compounds in a homologous series may exhibit variations in their chemical reactivity due to the presence of different substituents or functional groups.
The gradual increase in carbon chain length in a homologous series results in a systematic progression in the physical and chemical properties of the compounds. This predictable pattern is valuable for the study and classification of organic compounds. It enables chemists to make generalizations about the behavior and properties of compounds within a homologous series, even when specific properties are not known for individual members.
Overall, a homologous series provides a useful framework for the organization, classification, and understanding of the vast number of organic compounds found in nature and synthesized by chemists.
• In chemistry, a series of compounds which differ from each other by containing more or less of the same group of atoms; in the case of the paraffin series this group is CH2.
• A series of organic compounds, the succeeding members of which differ from each other by the radicle CH2.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.
The word "homologous" comes from the Greek roots "homos" which means "same" and "logos" which means "proportion" or "relationship". The term "homologous series" was introduced in the field of chemistry to describe a series of organic compounds that have the same functional group and similar chemical properties, with each member of the series differing in the number of carbon atoms.
The concept of homology in chemistry was first described by the French chemist Charles Gerhardt in the mid-19th century. He recognized that compounds with similar chemical properties could be classified into families or series based on their structure and composition. This led to the concept of homologous series, where each member had a similar structural pattern and a progressive increase in molecular size.