Carbon Allotropes and Covalent Bonds

• Carbon is the 15th most abundant element in the Earth's crust.

• Carbon has an atomic number of 6 and an atomic mass of 12u.

• Carbon's valency is 4.

• Carbon has 6 protons and 6 neutrons, with 2 electrons in the K shell and 4 in the L shell.

• The electronic arrangement of carbon is 2, 4.

• A covalent bond involves the sharing of electrons between atoms.

• Single, double, and triple covalent bonds are the three types of covalent bonds.

• Compounds with covalent bonds have low melting and boiling points.

• Covalent compounds are generally poor conductors of electricity due to the absence of charged particles.

• They are often soluble in organic solvents but not in water, with sugar being an exception..

• Catenation enables carbon to form strong covalent bonds with itself, leading to chains, branches, or rings.

• Polymerisation involves small molecules (monomers) joining to form large molecules (polymers).

• Isomerism is when compounds share a molecular formula but have different structures.

• Tetravalency allows carbon to form four covalent bonds, ensuring stability.

Allotropes

• Allotropes are various physical forms of an element.

Diamond

• Features a 3D network where each carbon bonds with four others, making it very hard.
• Diamond's structure results in high stability and strong covalent bonds.
• Diamonds are hard, transparent, and have a high refractive index, making them suitable for jewelry and abrasives.

Graphite

• Graphite consists of layers of hexagons held by weak forces, making it soft and slippery.
• Graphite is soft because there are only three covalent bonds per carbon along with delocalized electrons.
• Uses are found in pencils and lubricants, as it is soft.

Fullerene

• Fullerenes are hollow, cage-like structures containing 60 carbons, resembling a soccer ball.
• The hexagons and pentagons have strong covalent bonds between them.
• The material exhibits unique electronic properties and has uses in nanotechnology and drugs.

Hydrocarbons

• Hydrocarbons are organic compounds that contain Hydrogen and carbon atoms.

Saturated Hydrocarbons

• Saturated hydrocarbons are Alkanes.
• Alkanes have only single bonds.
• The formula for Alkanes is CnH2n+2.

Unsaturated Hydrocarbons

• Unsaturated hydrocarbons include Alkene and Alkynes.
• Alkenes feature double bonds with the formula CnH2n.
• Alkynes feature triple bonds with the formula CnH2n-2.

Functional Groups

• Hydrogen atoms can be replaced by heteroatoms (Cl, S, N, O) in hydrocarbons, forming functional groups.
• Functional groups determine a compound's properties.

Common Functional Groups

• Alcohol (-OH) functional group ends in -ol (e.g., Ethanol).
• Aldehyde (-CHO) functional group ends in -al (e.g., Ethanal).
• Ketone (-CO-) functional group ends in -one (e.g., Propanone).
• Carboxylic Acid (-COOH) functional group ends in -oic acid (e.g., Ethanoic acid).
• Amine (-NH2) functional group ends in -amine or starts with Amino-.

Naming Rules

• Identify the longest carbon chain, then number the chain to give the functional group the lowest number.
• The functional groups have priority over alkanes, alkenes, and alkynes, with the most important one getting the suffix.
• Suffix or prefix use is based on the functional group.

Priority Order

• COOH > -CHO > -CO- > -OH > -NH2.

Homologous Series

• A homologous series includes compounds sharing a general formula and differing only in the carbon chain length.
• Homologues share the molecule's general formula.
• -CH2 is the group homologs differ by, with a molecular mass difference of 14 μ.
• All homologs have similar chemical properties.
• Gradual changes in physical properties are shown across all homologs.
• Functional groups influence chemical properties.

Isomerism

• Isomers are compounds with matching molecular formula but varying structures.

Types of Hydrocarbons

• Straight chain hydrocarbons occur when each carbon atom bonds to one or two other carbon atoms.
• Branched chain hydrocarbons occur when each carbon atom bonds to one, two, or more than two other carbon atoms.
• Cyclic hydrocarbons occur when carbon atoms form a closed ring structure, like Cyclohexane (C6H12) and Benzene (C6H6).

Nomenclature:

• Common nomenclature is named after their sources of isolation.
• International Union of Pure and Applied Chemistry (IUPAC), founded in 1919, establishes naming rules in chemistry.

Chemical Properties of Carbon Compounds

• Carbon compounds undergo combustion (burning), oxidation and addition reactions.
• Unsaturated hydrocarbons undergo addition reactions and alkanes undergo substition reactions.

Combustion (Burning)

• Burning refers to when carbon burns in Oxygen to create more carbon dioxide, water, and heat

Oxidation

• Oxidation refers to when alcohols are treated with oxidising agents. KMnO4 and K2Cr207 can act as oxidising agents

Addition Reaction

• Addition reactions occur when unsaturated hydrocarbons (alkenes, alkynes) add H₂ in the presence of Nickel and palladium catalysts.

Substitution Reaction

• Substitution reactions occur when Alkanes react with halogens (Cl2, Br2) in the presence of sunlight.

Chemical Properties of Ethanol and Ethanoic Acid

Ethanol (C2H5OH)

• Ethanol is in liquid form at room temperature.
• Ethanol is soluble in water in all proportions.
• Commonly known as alcohol and is the active ingredient in all alcholic drinks.
• A good solvent in medicines like tincture iodine, cough syrups, and tonics, is Ethanol.
• Ethanol reacts with sodium to produce hydrogen gas and sodium ethoxide.
• 2Na + 2C2H5OH → 2C2H5O-Na+ + H2 is the Equation for this occurrence.
• At 443 K, when ethanol is heated with excess concentrated sulphuric acid, water is removed via dehydration and ethene is created.
• C2H5OH → CH2=CH2 + H2O is the equation for this, and the sulphuric acid is needed as a dehydrating agent.
• Denatured alcohol is ethanol mixed with chemicals to render it undrinkable.
• Denatured alcohol has industrial applications as a solvent, cleaner, and fuel and is cheaper due to tax exemptions

Ethanoic Acid (CH3COOH)

• Ethanoic Acid is commonly known as acetic acid, from the carboxylic acid group, with a 5-8% water mixture called Vinegar, for use as a preservative in goods like Pickles.
• A weak acid that doesn't fully ionize in water.
• If ethanoic acid freezes in winter, it is known as "glacial".

Reactions of Ethanoic Acid

• Esterification is when Ethanoic Acid reacts with ethanol in concentrated H2SO4 to create an ester (for flavor/scent).
• Saponification is the reaction when the reaction converts esters to carboxylic acids when treating with a base.
• Soap is created as a byproduct.
• Reacts with sodium hydroxide to form sodium ethanoate (sodium acetate) and water.
• Reacts with Na2CO3 or NaHCO3, producing carbon dioxide, water, and sodium acetate.

Soap/Detergent Molecule Structure

• Soap and detergent molecules feature hydrophilic and hydrophobic ends.
• The hydrophilic end is water-attracting and polar, while the hydrophobic end is oil-attracting and non-polar.

Cleansing Process (Micelle Formation)

• Oil does not naturally mix with water.
• The hydrophobic tails attract the grease, while hydrophilic heads attract the water when the oil is mixed with soap/detergent.
• Micelles are formed as molecules arrange themselves and surround the dirt.
• The dirt is trapped by micelles and lifted from the surface.
• Micelles are washed away and the dirt is removed when rinsed with water.

Hard Water

• Hard water has a high mineral content and is is rich with Calcium and Magnesium
• Hard water doesn't lather easily with soap and will leave scum and scale in appliances like pipes and boilers.
• Hair and skin can become rough when washed with hard water.

Soft Water

• Soft water has a low mineral content and is rich with sodium and potassium
• Soft water has the ability to create foam when lathered with soap
• Rair and distilled water or examples of the water.
• Soft water can sometimes smoothen your skin and hair when washed with it.