Classification of Chemicals

How Can We Classify Matter?

There are two distinct types of matter used for classification: homogeneous substance and heterogeneous substances. 

• A homogeneous substance consists of only ONE visible component 
• A heterogeneous substance consists of MORE THAN ONE visible component.  

The following chart provides a clear idea of where a substance would be classified. Keep in mind, figuring out whether a substance is homogeneous or heterogeneous is typically a simple matter of what the naked eye can distinguish. 

What is a Pure Substance? 

Similar to matter, there are two types of pure substances: Elements and Compounds. 

• Elements are substances that CANNOT be broken down into simpler substances by chemical reactions. 
• Compounds are substances that are made up of TWO OR MORE elements and can be changed into elements (or other compounds) by chemical reactions. 

Unlike matter, it is difficult to discern if something is a element or a compound as the differences are only "visible" on the atomic level.  

What is a Solution? 

A solution is a homogeneous mixture of two or more substances. More often than not, solutions come in the form of liquids but there are exceptions such as steel and fog. In a solution, there exists two key components: 

• The Solvent: The compound present in the greater amount. Water is the most common solvent.
• The Solute: The compound present in the lesser amount. 

Click here for an elaboration on this broad concept.

What Are Mixtures and How Are They Separated? 

Many mixtures are easy to identify but others can be easily confused as pure substances.  There are two types of mixtures: homogeneous mixtures and heterogeneous mixtures. 

• In homogenous mixtures, the different parts are not visible. 
• In heterogeneous mixtures, the different parts are visible.      

There are many methods and scientific procedures devised to separate mixtures and you would select one depending on which mixture you are working with:  

• By hand (Homogeneous and Heterogeneous mixtures) 
• Filtration (Heterogeneous mixtures only - Most commonly used method)  
• Distillation (Heterogeneous mixtures only)
• Crystallization (Heterogeneous mixtures only)
• Chromatography (Heterogeneous mixtures only) 

For more information, along with examples, regarding mixtures click here. 

-Simon Sierra