Naming Covalent Compounds

Introduction to Covalent Bonding

Covalent Bonding: Covalent bonding entails the sharing of electron pairs between non-metal atoms, enabling them to complete their outer electron shells and attain atomic stability. Visualise this as atoms "coming together" to conduct an "electron sharing" that results in stability, achieved through a complete outer electron shell.

Introduction to Identifying Covalent Compounds

Covalent compounds form when atoms share electrons with non-metal atoms. Recognising covalent compounds is essential for understanding molecular interactions.

Visual Aids and Checklist

Here is a flowchart for identifying covalent compounds:

Checklist for Identifying Covalent Compounds:

• Involves only non-metal elements
• Typically exist as gases or liquids
• No inclusion of metal elements

Systematic Naming of Covalent Compounds

Understanding systematic naming is vital for precise communication in scientific discourse.

USING PREFIXES IN COVALENT COMPOUNDS

Prefixes indicate the number of atoms of each element present in the compound.

List of Prefixes:

• 1: Mono-
• 2: Di-
• 3: Tri-
• ...up to 10

Naming Process Overview

• Start with the less electronegative element, followed by the more electronegative element with the suffix '-ide'.
• Employ numerical prefixes to denote the number of atoms.

Examples and Exercises

Practical Naming Examples

• CO: Carbon monoxide
• NO₂: Nitrogen dioxide

Additional Examples:

• Water (H₂O): Dihydrogen monoxide (though commonly called water)
• Methane (CH₄): Carbon tetrahydride (commonly known as methane)

Worked Example: To name N₂O₃:

1. Identify elements: Nitrogen and Oxygen
2. Apply prefixes: "di" for 2 nitrogen atoms, "tri" for 3 oxygen atoms
3. First element (nitrogen) with prefix: "dinitrogen"
4. Second element (oxygen) with prefix and "-ide" suffix: "trioxide"
5. Complete name: "Dinitrogen trioxide"

Avoiding Common Pitfalls

• Prefix Errors: Avoid using 'mono-' for the first element of binary compounds. Example: CO is "carbon monoxide", not "monocarbon monoxide".
• Electronegativity Errors: Ensure correct ordering of elements based on electronegativity by starting with the less electronegative element.

Lewis Dot Diagrams

Definition: Diagrams that depict electron sharing and bonds in molecules, illustrating how electrons form bonds through sharing.

Guide to Drawing Lewis Diagrams

Steps:

1. Count the total number of valence electrons.
2. Draw the structure, placing the least electronegative atom centrally.
3. Complete the electron arrangement for outer atoms, then the central atom.

Example:

• H₂O Lewis Diagram demonstrates the pairs and lone pairs of electrons.

Practice Problems with Solutions

1. Naming Exercises

Convert chemical formulas into systematic names:

• NO₂: Nitrogen dioxide
• CO: Carbon monoxide
• BF₃: Boron trifluoride
• H₂S: Dihydrogen sulphide

2. Formula Writing Practice

Write chemical formulas for the following compounds:

• Carbon monoxide: CO
• Phosphorus pentachloride: PCl₅