3.4.1 FORMULAE OF SIMPLE COMPOUNDS

Description

Quick Overview

This section explains the concept of binary compounds, their valency, and how to write chemical formulae for simple compounds.

Standard

In this section, students learn about binary compounds, which consist of two different elements. It covers writing chemical formulae based on the valencies of the constituent elements and provides examples to illustrate the concepts.

Detailed

Formulae of Simple Compounds

In chemistry, binary compounds are the simplest types of compounds made up of only two different elements. Writing the chemical formula of a compound involves understanding the valency of each element involved in the combination. Valency refers to the combining capacity of an element.

To write a chemical formula:
1. Identify the symbols of the elements involved.
2. Determine the valency of each element.
3. Cross over the valencies to balance the charges, ensuring the overall compound is neutral.

For example, the formula for hydrogen chloride is HCl. In this case, hydrogen (H) has a valency of 1, and chlorine (Cl) also has a valency of 1, so they combine in a 1:1 ratio. The same principle applies to more complex compounds, such as sodium carbonate (Na2CO3) where sodium's valency is 1 and carbonate has a valency of 2, resulting in two sodium ions to balance the charge of one carbonate ion.

Importance

Writing chemical formulae correctly is crucial in understanding chemical reactions and stoichiometry in chemistry.

Key Concepts

  • Binary Compounds: Compounds made of two different elements.

  • Valency: The combining capacity of an element.

  • Chemical Formula: A symbolic representation showing elements and their quantities.

  • Polyatomic Ions: Charged groups of covalently bonded atoms that behave as a single unit.

Memory Aids

🎵 Rhymes Time

  • If H and Cl make a pair, it's HCl, beyond compare!

📖 Fascinating Stories

  • Once upon a time, in a lab far away, H and Cl met and decided to bond. Together they formed HCl, a story of unity in diversity!

🧠 Other Memory Gems

  • B for Binary, C for Compound - remember that they are two elements bound!

🎯 Super Acronyms

BCE

  • Binary Compounds - Elements!

Examples

  • Example of water as a binary compound: H2O.

  • Example of sodium chloride: NaCl.

  • Example of calcium nitrate: Ca(NO3)2.

Glossary of Terms

  • Term: Chemical Formula

    Definition:

    A symbolic representation of the composition of a compound that indicates the elements present and the number of atoms of each.

  • Term: Binary Compound

    Definition:

    A chemical compound consisting of two different elements.

  • Term: Valency

    Definition:

    The combining capacity of an element, indicating how many electrons it can gain, lose, or share.

  • Term: Polyatomic Ion

    Definition:

    An ion composed of two or more atoms that are covalently bonded and that functions as a single ion.