Organic Chemistry Introduction

Grade 10 · Science · Study Guide

Discover the foundations of organic chemistry including carbon bonding, functional groups, and naming conventions for hydrocarbons and common organic compounds.

Organic chemistry is the study of carbon-containing compounds. Carbon is uniquely suited for this role because it can form four covalent bonds, creating chains, branches, and rings of virtually unlimited complexity. Carbon bonds to carbon, hydrogen, oxygen, nitrogen, halogens, and other elements to form millions of compounds.

Hydrocarbons contain only carbon and hydrogen. Alkanes (single bonds, CₙH₂ₙ₊₂) are saturated and named with -ane suffix (methane, ethane, propane...). Alkenes (one or more double bonds, CₙH₂ₙ) are unsaturated and named with -ene suffix. Alkynes (triple bonds) use -yne suffix. Aromatic hydrocarbons contain a benzene ring with delocalized electrons.

Functional groups are specific atom groups that give organic molecules their characteristic chemical properties. Common functional groups include hydroxyl (-OH, alcohols), carboxyl (-COOH, carboxylic acids), amino (-NH₂, amines), carbonyl (C=O, aldehydes and ketones), and ester (-COO-).

ISUPAC nomenclature provides a systematic naming system. The parent chain is the longest continuous carbon chain, numbered to give substituents the lowest possible numbers. Substituents and functional groups are indicated with prefixes or suffixes.

Key terms

Hydrocarbon
An organic compound containing only carbon and hydrogen atoms; classified as alkanes, alkenes, alkynes, or aromatic
Functional group
A specific arrangement of atoms within an organic molecule that determines its chemical properties and reactivity
Isomers
Compounds with the same molecular formula but different structural arrangements of atoms
Saturated hydrocarbon
An alkane with only single C-C bonds; general formula CₙH₂ₙ₊₂; cannot add more hydrogen
Unsaturated hydrocarbon
An alkene or alkyne containing C=C double or C≡C triple bonds; can undergo addition reactions
Polymer
A large molecule made of repeating monomer units; can be natural (proteins, starch) or synthetic (polyethylene, nylon)

Flashcards

Alkane
Saturated hydrocarbon with only single bonds; CₙH₂ₙ₊₂; names end in -ane (methane, ethane, propane...)
Alkene
Unsaturated hydrocarbon with at least one C=C double bond; CₙH₂ₙ; names end in -ene
Alkyne
Unsaturated hydrocarbon with at least one C≡C triple bond; CₙH₂ₙ₋₂; names end in -yne
Benzene (C₆H₆)
Simplest aromatic compound with a ring of 6 carbons and delocalized π electrons; unusually stable
Hydroxyl group (-OH)
Functional group in alcohols; makes compounds more polar and able to form hydrogen bonds
Carboxyl group (-COOH)
Functional group in carboxylic acids; acts as an acid by donating its H⁺
Structural isomers
Compounds with the same molecular formula but different connectivity of atoms (e.g., butane vs. isobutane)
Addition reaction
Reaction where atoms add across a double or triple bond in an unsaturated hydrocarbon

Questions

  1. What is the general molecular formula for alkanes?

    1. CₙH₂ₙ
    2. CₙH₂ₙ₊₂
    3. CₙH₂ₙ₋₂
    4. CₙHₙ
    Show answer

    Answer: CₙH₂ₙ₊₂

    Alkanes are saturated hydrocarbons with only single bonds; formula CₙH₂ₙ₊₂. For example, methane = CH₄ (n=1: 2(1)+2=4)

  2. An alcohol functional group is characterized by the presence of a hydroxyl (-OH) group bonded to a carbon atom.

    Show answer

    Answer: True

    Alcohols are defined by the -OH (hydroxyl) functional group attached to a carbon; examples: ethanol (CH₃CH₂OH)

  3. Which functional group is found in carboxylic acids?

    1. -OH
    2. -NH₂
    3. -COOH
    4. -CHO
    Show answer

    Answer: -COOH

    -COOH (carboxyl group) is the defining functional group of carboxylic acids; it consists of a carbonyl C=O and a hydroxyl -OH

  4. Compounds that have the same molecular formula but different structural arrangements of atoms are called ________.

    Show answer

    Answer: isomers

    Isomers share the same molecular formula but differ in their structural arrangement, resulting in different physical and chemical properties

  5. What is the IUPAC name for a 3-carbon alkane?

    1. Ethane
    2. Propane
    3. Butane
    4. Methane
    Show answer

    Answer: Propane

    Propane has 3 carbons. IUPAC names for alkanes: 1C=methane, 2C=ethane, 3C=propane, 4C=butane, 5C=pentane

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