Chemistry Chapter 4: Carbon and its Compounds

Chapter 4: Carbon and its Compounds

• Carbon compounds are of immense significance in various fields such as biology, chemistry, and materials science. They form the basis of life due to their presence in organic molecules like proteins, nucleic acids, and carbohydrates. Additionally, carbon-based materials are crucial in the development of advanced technologies, including pharmaceuticals and renewable energy solutions.

• in both elemental and combined forms

• Many everyday items are made of compounds of carbon

• Burning carbon-containing compounds produces carbon dioxide

• Carbon is present in the Earth's crust in minerals and the atmosphere as carbon dioxide

• Carbon's importance lies in its ability to form different compounds in various structures

• Carbon's ability to form covalent bonds with itself and other elements

• Carbon forms strong bonds, but weak intermolecular forces

4.1 Bonding in Carbon - The Covalent Bond

• Ionic compounds have high melting and boiling points and conduct electricity in solution or in the molten state
• Carbon compounds generally have low melting and boiling points compared to ionic compounds
• Carbon does not form ions in its compounds
• Carbon overcomes the need to gain or lose electrons by sharing electrons with other atoms
• This shared electron pair is a covalent bond
• Carbon's valency is 4, meaning it can form 4 covalent bonds
• Carbon can form single, double, or triple covalent bonds with other atoms or itself
• Molecules formed via covalent bonds typically have low melting and boiling points

Allotropes of Carbon

• Carbon exists in different forms, called allotropes
• Diamond and graphite are formed by carbon atoms
• Diamond has each carbon atom bonded to 4 other carbon atoms in a three-dimensional structure (very hard and non-conductive)
• Graphite has each carbon atom linked to three others in a hexagonal array (conductive layers)
• Fullerenes: Another allotrope of carbon, with carbon atoms arranged in a spherical or cylindrical shape (like footballs)

4.2 Versatile Nature of Carbon

• Carbon's ability for catenation allows it to form long carbon chains (single, double, or triple bonds) or rings
• Carbon can form strong bonds with various elements (H, O, N, S) giving rise to diverse compounds
• The nature of covalent bonds allows carbon to form a large number of compounds (more than any other element)

4.2.1 Saturated and Unsaturated Carbon Compounds

• Saturated compounds have carbon atoms linked by single bonds only
• Unsaturated compounds have double or triple bonds

4.2.2 Chains, Branches, and Rings

• Carbon atoms can be arranged in chains, branched chains, or rings
• Table 4.2 lists names and structures of saturated compounds with up to 6 carbon atoms

4.2.3 Homologous Series

• Homologous series is a series of compounds with the same functional group and similar chemical properties
• Each member differs by a —CH2— unit

4.3 Chemical Properties of Carbon Compounds

• Most carbon compounds burn in oxygen to produce carbon dioxide and heat/light (combustion)
• Saturated hydrocarbons burn cleanly, while unsaturated ones produce smoke and soot
• Some carbon compounds can undergo oxidation reactions
• Ethanol reacts with sodium metal to produce hydrogen gas
• Alcohols, under special conditions, can form a specific type of carbon compound called an ester
• Some properties of ethanoic acid (acetic acid):
• Ethanoic acid is a weak acid
• Esterification Reaction: reaction between an alcohol and ethanoic acid forms an ester, and water as a by-product
• Ethanoic acid reacts with carbonates and hydrogencarbonates producing carbon dioxide gas.
• Common uses include preservatives for food and as a component of many cleaning products.

4.4 Some Important Carbon Compounds: Ethanol and Ethanoic Acid

• Ethanol is commonly used in beverages and as a solvent
• Ethanoic acid reacts with different compounds. For example, it reacts with carbonates, hydrogencarbonates and a base forming different products.

4.5 Soaps and Detergents

• Soaps form micelles which help in cleaning clothes.

• Soap molecules have a hydrophilic (water-loving) end and a hydrophobic (water-fearing) end.

• The hydrophobic part dissolves grease, and the hydrophilic end attaches to the water, enabling removal

• Detergents have similar functionality but can function even in hard water (containing minerals).

• Hard water contains minerals such as calcium and magnesium which react with soap to form precipitates (scum), reducing cleaning effectiveness. Detergents do not react in the same way and are, therefore, suitable for use in hard water.

  Ethanol is used in preparing various medicines such as tonics.

• Ethanol reacts with sodium metal, forming sodium ethoxide and hydrogen gas

• Ethanol is oxidised under special conditions to ethanoic acid.