Organic vs. Inorganic Compounds and Hydrocarbons

Organic vs. Inorganic Compounds

Definitions

• Organic Compounds: Compounds containing the element carbon.

• Inorganic Compounds: Compounds that do not primarily contain carbon, often characterized by the presence of ionic bonding.

Examples of Compounds

• Organic:

  • H3PO2H3PO2

  • C2H4O2C2H4O2​

  • C2HCl2OC2HCl2O

  • HC6H7O6HC6H7O6​

• Inorganic:

  • H2SO4H2SO4

  • Na2SO2Na2SO2

  • CaCl2CaCl2​

Learning Objectives

• Discuss the importance of organic compounds.

• Classify chemical formulas as organic or inorganic.

• Compare and contrast organic vs. inorganic compounds based on physical/chemical properties.

• Identify various functional groups based on their chemical structure.

Organic Compounds

Historical Context

• Friedrich Wöhler (1828): Known as the father of organic chemistry, synthesized an organic compound from an inorganic source, specifically urea from ammonium cyanate.

Importance of Organic Compounds

• Organic compounds are essential components of living organisms and substances such as food, fuels, construction materials, and clothing.

Theory Discredited

• Wöhler's urea synthesis challenged the Vital Force Theory, which posited that organic compounds arise only from living organisms due to some vital force.

Organic vs. Inorganic Chemistry

Definitions

• Organic Chemistry: The study of carbon-containing compounds. Exceptions include carbon dioxide (CO2CO2), carbon monoxide (COCO), carbonates (CO32−CO32−), and cyanides (CN−CN−).

• Inorganic Chemistry: The study of elements and all non-carbon compounds, characterized by typically ionic bonding.

Examples of Inorganic Compounds

• Sodium chloride (NaClNaCl), Potassium phosphate (K3PO4K3PO4)

Comparison of Properties

Bonding within Molecules

• Organic: Covalent bonds.

• Inorganic: Generally ionic bonds.

Molecular Forces

• Organic: Weaker intermolecular forces.

• Inorganic: Strong intermolecular forces.

Physical State

• Organic: Gases, liquids, or low-melting-point solids.

• Inorganic: Usually high-melting-point solids.

Flammability

• Organic: Typically flammable.

• Inorganic: Generally non-flammable.

Solubility in Water

• Organic: Often lower solubility.

• Inorganic: Often higher solubility.

Electrical Conductivity

• Organic: Nonconductors.

• Inorganic: Conductors.

Reaction Rates

• Organic: Generally slower.

• Inorganic: Typically faster.

Summary of Properties Comparison

Understanding the Prevalence of Organic Compounds

Stability of Carbon Bonds

• Carbon Forms Stable Bonds: Carbon demonstrates an ability to form stable covalent bonds with itself and other elements like oxygen, nitrogen, sulfur, and halogens.

• Carbon molecules can range from very simple (e.g., methane, CH4CH4​) to complex structures with over a million carbon atoms.

Bonding Variability

• Carbon can form double (C=CC=C) or triple bonds (C≡CC≡C) with itself.

  • A carbon-carbon double bond (e.g., in ethene H2C=CH2H2C=CH2)

Structural Abundance

• Limitless Arrangements: Carbon can create different forms such as branched chains, ring structures, and linear chains.

Functional Groups

Definition

• A functional group is defined as an atom or group of atoms arranged in a specific manner, responsible for the characteristic chemical and physical properties of a molecule.

• All functional groups except alkanes contain at least one multiple bond or contain oxygen or nitrogen.

Importance

• Functional groups have unique properties that contribute significantly to biological and medical capabilities.

• Compounds with the same functional group typically share similar chemical behaviors.

Types of Functional Groups

• Alkanes: No functional group, consisting only of carbon and hydrogen connected by single bonds.

• Alkenes: Contains at least one carbon-carbon double bond.

• Alkynes: Contains at least one carbon-carbon triple bond.

• Aromatics: Consists only of carbons and hydrogens in a cyclic structure with alternating double bonds (e.g., benzene).

• Alcohols: Contain an -OH (hydroxyl) group, indicating alcohol character.

• Ethers: Characterized by the presence of oxygen between two carbon atoms.

• Amines: Contain nitrogen attached to carbon atoms.

• Aldehydes: Feature an oxygen doubly bonded to a terminal carbon.

• Ketones: Contain an oxygen doubly bonded to a carbon situated between two other carbons.

• Carboxylic Acids: Composed of a carbon with one double-bonded oxygen and one single-bonded oxygen.

• Esters: Similar to carboxylic acids but have an additional -OR group where R can be another hydrocarbon chain.

• Amides: Include both oxygen and nitrogen; the nitrogen is single-bonded to a carbon which also has a double-bonded oxygen attached.

• Halogens: Composed of one or more halogen atoms (F, Cl, Br, I) connected to carbon but not sandwiched between carbons.

Examples of Functional Groups

Alkane Structure

Representations of Propane

• Lewis Structure: H:C:C:C:HH:C:C:C:H

• Structural Formula: H−C−C−C−HH−C−C−C−H

• Line Diagram: Shows a condensed line representation (also known as the skeletal formula).

• Condensed Formula: C3H8C3H8 or CH3CH2CH3CH3CH2CH3​

Learning Objectives

• Write molecular and condensed formulas of organic compounds.

• Draw structural and line formulas for organic compounds.

• Classify alkanes as normal or branched.

Hydrocarbons

Definition

• Hydrocarbons are compounds composed solely of hydrogen and carbon atoms.

Importance

• Hydrocarbons are fundamental in comprehending the chemical properties of more complex biomolecules and are vital as a primary energy source, used for making various products including plastics, drugs, and synthetic fibers.

Classification of Hydrocarbons

Alkanes

General Formula

• The general formula for alkanes is expressed as:

  CnH2n+2CnH2n+2

  Where nn refers to the number of carbon atoms in the molecule.

Examples

• Methane (CH4CH4​): Simplest alkane and primary component of natural gas.

• Ethane (C2H6C2H6): Minor component of natural gas.

• Propane (C3H8C3H8): Commonly used for heating homes and in cooking.

Identifying Alkanes

• Alkanes can be either normal or branched.

  • Normal Alkane: All carbons are in a continuous chain.

  • Branched Alkane: At least one carbon is not part of the continuous chain.

Normal vs. Branched Naming

• Normal alkanes include structures such as:

  • CH3−CH2−CH2−CH2−CH3CH3−CH2−CH2−CH2−CH3​ (n-pentane)

• Branched examples include:

  • CH3−CH(CH3)−CH3CH3−CH(CH3)−CH3​ (isobutane or 2-methylpropane)

Structural Isomers

Definition

• Structural isomers are two or more compounds that have the same molecular formula but different arrangements of atoms.

Existence in Alkanes

• Alkanes exhibit structural isomerism with compounds having the same molecular formula but with differing bonding arrangements.

Practice

• Identify which pairs of structures represent structural isomers and which represent the same compound.

Alkane Nomenclature

Importance of Naming

• IUPAC (International Union of Pure and Applied Chemistry) governs the naming conventions.

• Learning the names of the first 20 alkanes and the structures of simple alkyl groups is crucial.

Steps for Nomenclature

1. Identify the Longest Carbon Chain: This provides the root name and ending.

2. Number the Chain: To give the lowest number to any carbon to which a substituent is attached.

3. Locate and Name Alkyl Groups: Identifying where branches occur and naming them.

4. Combine the Names: Create a full name that incorporates the longest chain and branches.

5. Designate Multiple Substituents: Show the positions of branches clearly and modify names for identical substituents with prefixes (di-, tri-, etc.).

Naming Examples (First 10 Alkanes)

Continued Names (11-20)

Alkyl Groups

• Definition: Alkyl groups are formed by removing one hydrogen atom from an alkane, changing its designation from ‘-ane’ to ‘-yl’. E.g., methane (CH4CH4) becomes methyl (−CH3−CH3).

First 5 Alkyl Groups