Carbon and Its Compounds

Vocabulary practice flashcards covering bonding, allotropes, organic nomenclature, chemical reactions, ethanol, ethanoic acid, and cleansing mechanisms in Class 10 Chemistry Chapter 4.

Carbon Abundance (Earth's Crust and Atmosphere)

The naturally occurring proportion of carbon, which accounts for $0.02\%$ in the earth's crust as minerals (carbonates, hydrogen-carbonates, coal, and petroleum) and $0.03\%$ in the atmosphere as carbon dioxide ($\text{CO}_2$).

Covalent Bond

A chemical bond formed by the sharing of an electron pair between two atoms, allowing both atoms to achieve a completely filled outermost shell and attain noble gas configuration.

Single Covalent Bond

A chemical bond formed when two atoms share one pair of electrons, commonly represented by a single line between the two bonded atoms (for example, in an $\text{H}_2$ molecule).

Double Bond

A covalent bond formed by the sharing of two pairs of electrons between two atoms, such as between two oxygen atoms to form an $\text{O}_2$ molecule.

Triple Bond

A covalent bond formed by the sharing of three pairs of electrons between two atoms, such as between two nitrogen atoms to form an $\text{N}_2$ molecule.

Allotropes of Carbon

Different structural forms of carbon existing in nature that possess identical chemical properties but widely varying physical properties, including diamond, graphite, and fullerenes.

Diamond

An allotrope of carbon in which each carbon atom is covalently bonded to four other carbon atoms to form a rigid three-dimensional structure, making it the hardest substance known.

Graphite

An allotrope of carbon wherein each carbon atom is bonded to three other carbon atoms in the same plane to form hexagonal arrays arranged in layers; it is smooth, slippery, and conducts electricity.

Fullerene (C-60)

An allotrope of carbon consisting of sixty carbon atoms arranged in the shape of a football, named after the geodesic dome architect Buckminster Fuller.

Catenation

The unique ability of carbon atoms to form stable covalent bonds with other carbon atoms, producing large molecules in the form of straight chains, branched chains, or rings.

Tetravalency

The characteristic of having a combining capacity of four, which enables carbon to form bonds with four other carbon atoms or with atoms of other monovalent elements.

'Vital Force' Theory

The historical postulate that organic carbon compounds could only be synthesized within a living system by a vital force, disproved in $1828$ by Friedrich Wöhler.

Friedrich Wöhler

The chemist who disproved the 'vital force' theory in $1828$ by synthesizing the organic compound urea from the inorganic precursor ammonium cyanate.

Saturated Hydrocarbons (Alkanes)

Carbon compounds containing only hydrogen and carbon linked exclusively by single covalent bonds between carbon atoms, typically not very reactive.

Unsaturated Hydrocarbons

Compounds of carbon and hydrogen containing one or more double bonds (alkenes) or triple bonds (alkynes) between carbon atoms, exhibiting greater reactivity than saturated hydrocarbons.

Structural Isomers

Chemical compounds having identical molecular formulas but different structural arrangements, such as normal butane and isobutane with the molecular formula $\text{C}_4\text{H}_{10}$.

Hydrocarbons

Organic compounds composed exclusively of the elements carbon and hydrogen.

Heteroatom

An atom other than carbon or hydrogen (such as halogens, oxygen, nitrogen, or sulphur) that replaces one or more hydrogen atoms in a hydrocarbon chain to satisfy carbon's valency.

Functional Group

A heteroatom or specific grouping of atoms (such as $-\text{OH}$, $-\text{CHO}$, $-\text{CO}-$, or $-\text{COOH}$) that confers distinct chemical properties to an organic compound regardless of carbon chain length.

Homologous Series

A family of organic compounds containing the same functional group that substitutes for hydrogen in a carbon chain, where successive members differ by a $-\text{CH}_2-$ unit and a molecular mass of $14\,\text{u}$.

Combustion (of Carbon)

An exothermic oxidation reaction in which carbon or carbon compounds burn in oxygen to yield carbon dioxide, accompanied by the release of heat and light.

Oxidising Agents

Substances capable of adding oxygen to other compounds, such as alkaline potassium permanganate ($\text{KMnO}_4$) or acidified potassium dichromate ($\text{K}_2\text{Cr}_2\text{O}_7$) converting alcohols to carboxylic acids.

Addition Reaction

A chemical reaction in which unsaturated hydrocarbons add hydrogen atoms across multiple bonds in the presence of catalysts like nickel ($\text{Ni}$) or palladium ($\text{Pd}$) to produce saturated hydrocarbons.

Catalysts

Substances that initiate or alter the rate of a chemical reaction without themselves undergoing any permanent chemical change or being consumed.

Substitution Reaction

A reaction characteristic of saturated hydrocarbons in which one type of atom or group of atoms replaces another atom, such as chlorine replacing hydrogen atoms in methane one by one under sunlight.

Absolute Alcohol

Pure, undiluted ($100\%$) ethanol; ingesting even a small quantity can be lethal.

Denatured Alcohol

Ethanol rendered unfit for human consumption by adding toxic adulterants like methanol and blue dyes to prevent industrial-grade alcohol from being diverted for drinking.

Glacial Acetic Acid

Pure ethanoic acid ($\text{CH}_3\text{COOH}$), which freezes into ice-like crystals during winter in cold climates due to its melting point of $290\,\text{K}$.

Vinegar

A $5\text{--}8\%$ aqueous solution of acetic acid (ethanoic acid) widely utilized as a food preservative in pickles.

Esterification Reaction

A condensation reaction between a carboxylic acid and an alcohol catalyzed by an acid to produce water and a sweet-smelling organic compound called an ester.

Saponification

The reaction of an ester with a strong alkali (such as sodium hydroxide, $\text{NaOH}$) to produce an alcohol and the sodium salt of a carboxylic acid, used industrially to prepare soap.

Soap

A cleansing agent consisting of a sodium or potassium salt of a long-chain carboxylic acid possessing both a hydrophilic ionic end and a hydrophobic hydrocarbon tail.

Micelle

A colloidal cluster formed by soap molecules in water where hydrophobic hydrocarbon tails point inward around trapped oily dirt while hydrophilic ionic heads face outward into water.

Scum

An insoluble curdy precipitate formed when soap molecules react with the calcium ($\text{Ca}^{2+}$) and magnesium ($\text{Mg}^{2+}$) ions present in hard water.

Detergents

Cleansing agents typically composed of sodium salts of sulphonic acids or ammonium salts with chloride or bromide ions that remain effective in hard water without forming insoluble precipitates.