Class X Science: Carbon and its Compounds

Vocabulary flashcards covering the key terms, definitions, allotropes, bonding properties, reactions, and functional groups of Carbon and its Compounds for Class X Science.

Carbon

A non-metallic element represented by the symbol $C$, with atomic number $6$, mass number $12$, and ranking as the 15th most abundant element in the Earth's crust.

Covalent Bond

A chemical bond formed by the mutual sharing of electron pairs between two atoms so that both achieve a stable noble gas electronic configuration.

Catenation

The unique property of carbon to form strong and stable covalent bonds with other carbon atoms, resulting in linear chains, branched chains, or cyclic ring structures.

Tetravalency

The state of carbon having four valence electrons, enabling it to form four covalent bonds with other carbon atoms or monovalent and multivalent elements ($H$, $Cl$, $O$, $N$, $S$) to complete its octet.

Allotropes

Different physical forms of the same chemical element in which the atoms are bonded and arranged differently, giving them distinct physical properties while maintaining identical chemical properties.

Diamond

A rigid, 3-D allotrope of carbon in which each carbon atom is bonded to four other carbon atoms in a tetrahedral arrangement; it is the hardest natural substance and does not conduct electricity due to the absence of free electrons.

Graphite

A soft, slippery allotrope of carbon where each carbon atom is bonded to three other carbon atoms in hexagonal planar layers that slide over one another; it conducts electricity because of delocalized free electrons.

Fullerenes

A class of carbon allotropes consisting of carbon atoms arranged in spherical structures resembling footballs or geodesic domes, first identified as $C_{60}$ (Buckminsterfullerene).

Hydrocarbons

Organic chemical compounds composed exclusively of carbon and hydrogen atoms.

Saturated Hydrocarbons (Alkanes)

Hydrocarbons in which all carbon-carbon bonds are single bonds, having the general formula $C_n H_{2n+2}$; they are relatively unreactive.

Unsaturated Hydrocarbons

Hydrocarbons that contain one or more carbon-carbon double bonds (alkenes, general formula $C_n H_{2n}$) or carbon-carbon triple bonds (alkynes, general formula $C_n H_{2n-2}$), which are more reactive than saturated hydrocarbons.

Heteroatom

An atom such as chlorine, bromine, oxygen, nitrogen, or sulphur that replaces one or more hydrogen atoms in a hydrocarbon chain.

Functional Group

An atom or a group of atoms that replaces hydrogen in a carbon chain and imparts specific chemical characteristics to the compound, regardless of the length or nature of the carbon chain.

Homologous Series

A family of organic compounds containing the same functional group and similar chemical properties, where each successive member differs from the previous one by a $-CH_2-$ unit ($14\,\text{u}$ difference in molecular mass).

Isomerism

The phenomenon wherein compounds share the identical molecular formula but possess distinct structural formulas and arrangements of atoms.

Lewis Dot Structures

Diagrammatic representations of molecules showing the valence electrons of constituent atoms as dots to illustrate the sharing or transfer of electrons during chemical bond formation.

Combustion Reaction

An exothermic oxidation process wherein carbon or carbon compounds burn in the presence of oxygen to produce carbon dioxide, heat, light, and water (for hydrogen-containing compounds).

Hydrogenation Reaction

An addition reaction in which unsaturated hydrocarbons react with hydrogen gas in the presence of a catalyst like nickel ($Ni$) or palladium ($Pd$) to produce saturated hydrocarbons (e.g., converting liquid vegetable oils into solid fats/vegetable ghee).

Substitution Reaction

A characteristic reaction of saturated hydrocarbons where an atom or a group of atoms replaces hydrogen atoms one by one in the presence of sunlight (e.g., $CH_4 + Cl_2 \rightarrow CH_3 Cl + HCl$).

Denatured Alcohol

Industrial ethyl alcohol ($C_2 H_5 OH$) rendered toxic and unfit for drinking by the addition of poisonous substances like methanol and a blue dye for easy identification.

Glacial Acetic Acid

Pure ethanoic acid ($CH_3 COOH$), so called because its melting point is $290\,\text{K}$ ($17^\circ\text{C}$), causing it to freeze easily into ice-like crystals in cold climates.

Vinegar

A dilute $5\text{--}8\%$ solution of ethanoic acid in water widely utilized as a food preservative.

Esterification Reaction

A condensation reaction between a carboxylic acid and an alcohol in the presence of an acid catalyst to produce a pleasant, sweet-smelling ester and water.

Saponification Reaction

The alkaline hydrolysis of an ester using a strong base such as sodium hydroxide ($NaOH$) to yield an alcohol and the sodium salt of the carboxylic acid, used industrially to produce soap.

Soap

Sodium or potassium salts of long-chain carboxylic acids possessing a hydrophilic ionic head and a hydrophobic hydrocarbon tail.

Detergents

Sodium salts of sulphonic acids or ammonium salts with chloride or bromide ions that retain effective cleansing action even in hard water without generating scum.

Micelle

A spherical colloidal structure formed by soap molecules in water where hydrophobic carbon tails orient inward toward an oil/dirt droplet while hydrophilic ionic heads orient outward toward the surrounding water.

Scum

An insoluble curdy precipitate created when ordinary soap molecules react with calcium ($Ca^{2+}$) and magnesium ($Mg^{2+}$) ions present in hard water, which inhibits foam formation.