Classification of Matter October 1 , 2009

Understanding matter begins with how we name it
We can divide matter into 2 types:
- Homogeneous substances
- Heterogeneous substances

Homogeneous - consists of only one visible component


· Distilled water, oxygen, graphite.
Heterogeneous – contain more than one visible component
· Chocolate chip cookie, granite.

Matter
- Homogeneous - Heterogeneous
Substances substances
- Pure substances - homogeneous - Mechanical
-element Mixture Mixture
- Compound - solution

Pure substances
2 types:
Elements - substances that cannot be broken down into simpler substances
By chemical reactions
· Oxygen, Iron, Magnesium.
Compounds - substances that are made up of 2 or more element and can be changed into
Elements (or other compounds) by chemical reactions
3o2 ----> 2o3
H2O ----> H2 + o2
-water, sugar
Formic acid (ant bite venom)
Acetic acid (vinegar)
Butyric acid

Telling the difference
- Difference is only ‘visible’ on the atomic level.
- One method is to connect the substance to an electric current. This technique called electrolysis can split the compound apart into its constituent elements.

Electrolysis water

Solutions
A homogeneous mixture of 2 or more substances
- Usually involve liquids but don’t have to (fog, steel)
- The component present in greater amount is the solvent
water is the most common
symbol (aq) is used when something is dissolved in water
- The component present in smaller amount is the solute

Mixtures
- Many mixtures are easy to identify but others are easily confused as pure substances
- In heterogeneous mixtures the different parts are visible( granite sand, fog)
- In homogeneous mixtures the different parts are not visible(salt water, air, brass)

Separating mixtures
- Many methods to separate mixtures depending on the type of mixture
All physical changes:
Heterogeneous mixtures
· By hand
· Filtration
Homogeneous mixtures
· Distillation
· Crystallization
· chromatography


(Christine Yaco blog entry)