Chapter 12: Introduction to Organic Chemistry – Hydrocarbons (GOB Chemistry Study Notes)

Introduction to Organic Chemistry

Definition

Organic chemistry is the branch of chemistry that studies compounds containing carbon. Organic compounds are fundamental to life and are found in many everyday products.

• Organic compound: A chemical compound that always contains carbon and hydrogen atoms.

• May also contain other nonmetals such as oxygen, sulfur, nitrogen, phosphorus, or halogens (e.g., fluorine, chlorine).

• Common products containing organic compounds include gasoline, medicines, shampoos, plastics, and perfumes.

Properties of Organic Compounds

General Characteristics

Organic compounds exhibit distinct physical and chemical properties compared to inorganic compounds.

• Usually have covalent bonds.

• Typically possess low melting and boiling points.

• Are flammable and undergo combustion.

• Are not soluble in water unless a polar group is present.

• Example: Vegetable oil is a mixture of organic compounds and is not soluble in water.

Comparison of Organic and Inorganic Compounds

Key Differences

Organic and inorganic compounds differ in composition, bonding, and physical properties.

Property	Organic	Inorganic
Elements Present	C and H, sometimes O, S, N, P, or Cl (F, Br, I)	Most metals and nonmetals
Type of Particles	Molecules	Mostly ions
Bonding	Mostly covalent	Many are ionic, some covalent
Polarity	Nonpolar unless a strongly electronegative atom is present	Most are ionic or polar covalent, a few are nonpolar covalent
Melting Point	Usually low	Usually high
Boiling Point	Usually low	Usually high
Flammability	High	Low
Solubility in Water	Not soluble unless a polar group is present	Most are soluble unless nonpolar

Hydrocarbons

Definition and Types

A hydrocarbon is an organic compound containing only hydrogen and carbon atoms. Hydrocarbons are classified based on the types of bonds between carbon atoms.

• Saturated hydrocarbon: All bonds in the molecule are single bonds (alkanes).

• Unsaturated hydrocarbon: Contains one or more double or triple bonds (alkenes and alkynes).

Bonding in Organic Molecules

In organic molecules, each carbon atom forms four bonds to achieve a stable octet configuration.

• Example: In methane ($CH_4$), the carbon atom shares its four valence electrons with four hydrogen atoms, forming a tetrahedral structure.

Representations of Hydrocarbons

Structural Formulas

Hydrocarbons can be represented in several ways to show the arrangement of atoms and bonds:

• Ball-and-stick model: Shows atoms as spheres and bonds as sticks.

• Space-filling model: Illustrates the relative sizes of atoms.

• Expanded structural formula: Shows all atoms and bonds explicitly.

• Condensed structural formula: Groups each carbon atom with its attached hydrogen atoms.

• Line-angle formula: Uses zigzag lines where ends and corners represent carbon atoms.

Additional info:

These notes are based on textbook slides for a GOB Chemistry course, focusing on the introduction to organic chemistry and the properties and classification of hydrocarbons. The content is highly relevant for college-level GOB Chemistry students.