CHEM 11 A

Thursday, October 1, 2009 7:54 PM

Today, our class learned alot from Mr. Doktor and here are some materials we learned:) :

Classification of Matter

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

-Homogeneous: consists of only one visible component
e.g. Distilled Water, Oxygen, Graphite

-Heterogeneous: contain more than one visible component
e.g. Chocolate Chip Cookie, Granite

Pure Substances

-There are two types of Pure Substances: Elements and Compounds

-Elements: substances that cannot be broken down into simpler substances by chemical reactions
e.g. Oxygen, Iron, Magnesium

-Compounds: substances that are made up of 2 or more elements and can be changed into elements(or other compounds) by chemical reactions
e.g. Water, Sugar

Telling the Difference

- It is often very difficult to know if something is an element or a compound
->the differences are 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

Solution

- A solution is a homogeneous mixture of two or more substances
-> sloutions usually involve liquids but don't have to (Fog, Steel)

- The component present in greater amount is the solvent
-> water is the most common solvent
-> the symbol(aq) is used when something is dissolved in water

- The component present in smaller amount is the solute
-> in salt water, salt 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 clearly visible (Granite, Sand, Fog)

- In Homogeneous mixtures the different parts are not visible
(Salt Water, Air, Brass)

Separating Mixtures

- There are many methods to separate mixtures, depending on the type of mixture
-> By hand
-> Filtration
-> Distillation
-> Crystallization
-> Chromatography