Carbon And its Compounds-D

CloseA functional group is an atom or group of atoms that is responsible for the characteristic chemical reactions of a compound. For example, –OH (alcohol) gives different properties than –COOH (carboxylic acid), even if the carbon chain is the same.

CloseIn IUPAC nomenclature, the suffix (e.g., -ol, -al, -one) or prefix (e.g., chloro-, hydroxy-) indicates the presence of a specific functional group. For example, ethanol contains the –OH group, indicated by the suffix ‘ol’.

CloseIn IUPAC naming, the final ‘e’ of the parent alkane name (e.g., propane) is dropped before adding a suffix that begins with a vowel. For example: propane → propanol, propane → propanal. It is retained only if the suffix begins with a consonant.

CloseEthane (C₂H₆) and propane (C₃H₈) are successive members of the alkane homologous series. They differ by one –CH₂ group (methylene unit). Both have the same functional group (no functional group, only C–C and C–H single bonds).

CloseAs molecular mass increases in a homologous series, the surface area and van der Waals forces between molecules increase. More energy is required to overcome these forces, leading to higher melting and boiling points.

ClosePropane (C₃H₈) and butane (C₄H₁₀) differ by one –CH₂ group. Butane has one additional carbon and two additional hydrogens compared to propane. This is consistent for all successive alkanes (CₙH₂ₙ₊₂).

CloseIn IUPAC nomenclature, the suffix ‘-yne’ denotes a carbon-carbon triple bond (alkyne). For example, ethyne (C₂H₂), propyne (C₃H₄). Double bonds are indicated by ‘-ene’, and single bonds by ‘-ane’.

CloseThe suffix ‘-ene’ indicates a carbon-carbon double bond (alkene). For example, ethene (C₂H₄), propene (C₃H₆). Triple bonds use ‘-yne’, and single bonds use ‘-ane’ for saturated hydrocarbons.

CloseMethane (CH₄) and ethane (C₂H₆) are not successive homologues? Actually, methane (C₁) and ethane (C₂) differ by one –CH₂ group? Wait: C₂H₆ minus CH₄ = CH₂. Yes, that’s correct. Difference = one carbon and two hydrogens = –CH₂ unit.

CloseThe alkene series (CₙH₂ₙ) starts with n=2 because a double bond requires at least two carbon atoms. Ethene (C₂H₄) is the first member. “Methene” (CH₂) does not exist as a stable compound.

CloseA heteroatom is any atom other than carbon or hydrogen (e.g., O, N, S, Cl, Br) that replaces a hydrogen atom in a hydrocarbon. This often creates a functional group and changes chemical properties.

CloseIn IUPAC nomenclature, the suffix ‘-one’ indicates a ketone functional group (C=O group bonded to two carbon atoms). For example, propanone (CH₃–CO–CH₃). Aldehydes use ‘-al’, alcohols use ‘-ol’, and acids use ‘-oic acid’.

CloseA homologous series is a group of organic compounds with the same functional group (e.g., –OH for alcohols) and similar chemical properties, where each successive member differs by a –CH₂ unit. Examples: methanol, ethanol, propanol.

CloseA functional group is introduced into a hydrocarbon by replacing one or more hydrogen atoms with another atom or group of atoms. For example, replacing H in CH₄ with –OH gives CH₃OH (methanol).

CloseAll members of a homologous series share the same functional group (e.g., –OH for alcohols, –COOH for carboxylic acids). Their molecular masses, physical states, and colours vary gradually, but the functional group remains constant.

CloseAs molecular mass increases in a homologous series, physical properties (melting point, boiling point, density, solubility) change gradually in a predictable manner. Chemical properties remain similar, not identical, but show gradation.

CloseAlkanes are saturated hydrocarbons with only single bonds. The general formula is CₙH₂ₙ₊₂ where n ≥ 1. For n=1: CH₄; n=2: C₂H₆; n=3: C₃H₈. CₙH₂ₙ is for alkenes; CₙH₂ₙ₋₂ is for alkynes.

CloseAs molecular mass increases, intermolecular forces (van der Waals) increase, causing melting and boiling points to rise gradually. Functional group remains same; most organic compounds are colourless; reactivity pattern is similar, not gradually changing.

ClosePropene is an alkene with three carbon atoms and one double bond. Using alkene formula CₙH₂ₙ with n=3 gives C₃H₆. Its structure is CH₂=CH–CH₃. C₃H₈ is propane (alkane), C₃H₄ is propyne (alkyne).

CloseEach successive member of a homologous series has one more carbon and two more hydrogen atoms than the previous member. This difference is a methylene (–CH₂) group. For example, ethane (C₂H₆) → propane (C₃H₈) adds –CH₂.

CloseAll members of a homologous series contain the same functional group (e.g., all alcohols have –OH, all aldehydes have –CHO). Molecular mass, melting point, and boiling point all increase as the carbon chain lengthens.

CloseA heteroatom (like O, N, S, or halogen) introduces a specific functional group (e.g., –OH, –NH₂, –Cl) that determines the chemical behaviour of the compound. The functional group is named after the heteroatom and its bonding pattern.

CloseDue to catenation, carbon atoms can bond to each other to form chains of any length—from 1 carbon (methane) to thousands of carbons (polymers, biological macromolecules). There is no fixed upper limit.

CloseThe alkene series (CₙH₂ₙ) also differs by a –CH₂ unit between successive members. For example, ethene (C₂H₄) → propene (C₃H₆) adds –CH₂. The difference is always one carbon and two hydrogens.

CloseThe atomic mass (relative atomic mass) of carbon is 12.01 u, approximately 12 u. Carbon-12 is the standard reference for atomic masses. Atomic number is 6, not atomic mass.

CloseFor unsaturated hydrocarbons, the suffix ‘-ane’ (indicating single bonds) is replaced by ‘-ene’ for double bonds and ‘-yne’ for triple bonds. For example: ethane → ethene → ethyne.

CloseIUPAC nomenclature first identifies the longest continuous carbon chain (parent chain). Then, the positions of branches and functional groups are indicated. Molecular mass and colour are not used in naming; functional group is part of the suffix/prefix but the chain is primary.

CloseC₂H₆ (ethane) and C₃H₈ (propane) are successive alkanes. C₃H₈ minus C₂H₆ = CH₂. The difference is one –CH₂ group (methylene unit).

CloseMethanol (CH₃OH) contains the hydroxyl group (–OH) attached to a carbon atom, which is the defining feature of alcohols. The suffix ‘-ol’ indicates alcohol. Methanal is an aldehyde, methanoic acid is an acid.

CloseEthanol (C₂H₅OH or CH₃–CH₂–OH) has two carbon atoms. The prefix ‘eth-’ indicates two carbons. Methanol has one carbon, propanol has three, butanol has four.

CloseThe functional group is the reactive centre of a molecule. Hydrocarbons without functional groups (alkanes) are relatively unreactive. Introducing a functional group (e.g., –OH, –COOH, –CHO) makes the compound chemically reactive and gives it characteristic reactions.

CloseMembers of a homologous series have similar chemical properties because they share the same functional group. Physical properties (melting point, boiling point, density) change gradually and are not identical, only similar in trend.

CloseButene is an alkene with four carbon atoms and one double bond. Using alkene formula CₙH₂ₙ with n=4 gives C₄H₈. Isomers exist (1-butene, 2-butene, isobutylene). C₄H₁₀ is butane (alkane), C₄H₆ is butyne (alkyne).

CloseThe base name for a three-carbon alkane is propane. Prefixes: meth- (1 C), eth- (2 C), prop- (3 C), but- (4 C), pent- (5 C), etc. The suffix ‘-ane’ indicates single bonds (alkane).

CloseThe functional group determines polarity and ability to form hydrogen bonds with water (e.g., –OH, –COOH increase solubility). Chain length affects solubility (longer chains decrease solubility), but the functional group is the primary determinant of solubility behaviour.

CloseEthene (ethylene) has two carbon atoms with a double bond. Formula = C₂H₄. CH₄ = methane, C₂H₂ = ethyne, C₂H₆ = ethane.

ClosePropane with a ketone group (C=O on the middle carbon) gives propanone (acetone, CH₃–CO–CH₃). The suffix ‘-one’ indicates a ketone. Propanal is an aldehyde, propanol is an alcohol, propanoic acid is a carboxylic acid.

CloseHomologues are members of the same homologous series—they have the same functional group and similar chemical properties, but different carbon chain lengths (differ by –CH₂). Isomers have same molecular formula but different structures.

ClosePropanol is a three-carbon alcohol (C₃H₇OH). There are two isomers: propan-1-ol (CH₃–CH₂–CH₂OH) and propan-2-ol (CH₃–CH(OH)–CH₃). C₂H₅OH = ethanol, CH₃OH = methanol, C₄H₉OH = butanol.

CloseSuccessive homologues differ by a –CH₂ group. Mass of C = 12 u, mass of H₂ = 2 u, total = 14 u. For example, methane (CH₄ = 16 u) and ethane (C₂H₆ = 30 u) differ by 14 u.

CloseThese are all alcohols with the same functional group (–OH) and differ by successive –CH₂ units. They form the alcohol homologous series: methanol, ethanol, propanol, butanol.

CloseThe atomic mass of hydrogen is approximately 1.008 u, taken as 1 u for most calculations. Hydrogen has one proton and (usually) no neutrons in its most common isotope (protium).

CloseHomologous series organize organic compounds into families with predictable trends. Knowing one member helps predict properties of others. This reveals relationships between structure and properties within a functional group class.

CloseBecause all members contain the same functional group, they undergo the same types of chemical reactions. For example, all alcohols react with sodium to release hydrogen; all alkenes undergo addition reactions.

CloseWhen the final ‘e’ of the alkane name “propane” is removed, we get the root “propan-”, which is then used before adding a suffix (e.g., propanol, propanal). “Propan” itself is not a compound name but the carbon chain root.

CloseThe functional group determines the chemical reactivity and most physical properties (polarity, hydrogen bonding, solubility, acidity/basicity). Chain length modifies these (e.g., boiling point), but the functional group is the primary determinant.

CloseCH₃OH (methanol) contains the hydroxyl group (–OH) attached to a carbon atom. This is the alcohol functional group. Aldehydes have –CHO, ketones have C=O with two carbons attached, acids have –COOH.

CloseThe prefix ‘but-’ indicates four carbon atoms. Butanol is an alcohol with four carbons (C₄H₉OH). Methanol = 1C, ethanol = 2C, propanol = 3C, butanol = 4C.

CloseAfter forming the carbon skeleton, each carbon has a certain number of unused valencies (free valencies). Functional groups attach to the carbon chain by using these free valencies, forming covalent bonds. They are not attached by metallic or ionic bonds.

CloseThe IUPAC naming system provides a unique name for each organic compound that directly encodes its structure (carbon chain length, branching, position and type of functional groups). This allows chemists to deduce the molecular structure from the name.