Classification of Chemicals

Understanding matter begins w/ how we name it. We can divide matter into 2 types:
-Homogeneous: Consists of only one visible compound
-ex: distilled water, oxygen, graphite
-Heterogeneous: Contains more than one visible component
-ex: chocolate chip cookie, granite

Pure Substances

There are 2 types of Pure Substances:
-Elements: Substances that cannot be broken down into simpler substances by chemical reactions
-ex: oxygen, iron, magnesium
-Compounds: Substances that are made up of 2/more elements and can be changed into elements (or other compounds) by chemical reactions
-water(H2O), sugar(C12H22O11)

H2O + energy → (H2) + (O2)
∟ compounds split apart(by adding energy)

Telling the Difference

To identify an element or compound, the difference is only "visible" on the atomic level
One method is to connect the substance to an electric current.
-(Electrolysis) can split the compound apart into its constituent elements

Solution

A solution is a homogeneous mixture of 2/more substances
-Usually involve liquids (not always, like fog & steel)
The component present in greater amount is the solvent
-Water is most common solvent
-The symbol (aq) is used when something is dissolved
The component present in smaller amount is the solute

Mixtures

Mixtures can be easily identified, or can be confused as pure substances
-Heterogeneous mixtures, different parts clearly visible (granite, sand fog)
-Homogeneous mixtures, different parts aren't visible (salt water, air, brass)

Separating Mixtures

Many methods to separate mixtures, depending on type:
-By hand
-Filtration*
-Distillation*
-Crystallization
-Chromatography

^All physical changes
*Heterogeneous mixtures only

-Paulo Santillan