Matter can be classified based on its physical state, composition, and purity. The main ways to classify matter are:
1. By Physical State
- Solids: Have a fixed shape and volume, with particles closely packed in a uniform structure.
- Liquids: Have a fixed volume but take the shape of their container, with particles more loosely packed than solids.
- Gases: Have neither fixed shape nor fixed volume, expanding to fill their container with particles far apart
2. By Composition
Matter is broadly divided into:
A. Pure Substances
- Have a constant composition and uniform properties throughout.
- Cannot be separated into other kinds of matter by physical means.
- Two types:
- Elements: Cannot be broken down into simpler substances by chemical means (e.g., oxygen, gold).
- Compounds: Made of two or more elements chemically combined in fixed ratios and can be broken down chemically into elements or simpler compounds (e.g., water, sucrose)
B. Mixtures
- Composed of two or more different substances physically combined.
- Components retain their individual properties and can be separated by physical methods.
- Two types:
- Homogeneous mixtures (solutions): Uniform composition throughout (e.g., salt dissolved in water).
- Heterogeneous mixtures: Different regions have different compositions and properties (e.g., salad, pizza)
Summary Table
Classification Criterion| Categories| Description
---|---|---
Physical State| Solid, Liquid, Gas| Based on shape and volume characteristics
Composition| Pure Substance, Mixture| Based on uniformity and separability
Pure Substance| Element, Compound| Elements cannot be chemically broken down;
compounds can
Mixture| Homogeneous, Heterogeneous| Uniform vs. non-uniform composition
This classification helps in understanding the nature and behavior of matter in different contexts
