Chemical Analysis
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Element
An element is a substance that consists of only one type of atom and it cannot be broken down into anything simpler by chemical means 
Compounds
A compound is a substance that consist of two or more different elements chemically bonded together 
What are elements and compounds examples of
Pure substances
Pure substance
Is a single element or compound and is not mixed with any other substance 
How do we sometimes determine a substances purity
Pure substances have specific melting and boiling points that can be used to determine purity Chromatography may also be used
Mixture
A mixture is defined as two more substances mixed together, which are usually easy to separate (not chemically combined)
Name some pure substances
Diamond only contains the element carbon Water only contains the compound water Table salt only contains the compound sodium chloride
Name some mixtures
Air is a mixture of oxygen, carbon dioxide, nitrogen and other trace gases Mineral water is a mixture of water and dissolved salts Milk is a mixture of water, lactose, fat and minerals
Describe a compound
A compound is a pure substance A chemical reaction occurs when a compound is formed and there is an energy change The composition of a compound is always the same The properties of a compound are different from those of the elements making up the compound Chemicals compound are difficult to separate and can only be broken by chemical means
What is one way of breaking a compound down by chemical means
Molten sodium chloride can be decomposed to give sodium and chlorine by electrolysis
Describe a mixture
Contains two or more substances When a mixture is made no chemical change takes place The composition of a mixture can vary The properties of a mixture are the same as those of the individual elements making up the mixture Mixtures are easy to separate using physical means
Wants one way a mixture can be separated by physical means
Sodium chloride crystals can be obtained from sodium chloride solution by evaporation
Name some less obvious compounds
Methane Ethanol Salt Marble chips Baking soda Sugar Ice
Describe a pure element on a diagram
Single set of same coloured dots Or pairs of same coloured dots
Describe a mixture of two elements on a diagram
Two sets of different coloured dots (they can be pairs as well)
Describe a diagram of a pure compound
Repeat of the compound throughout region
Describe on a diagram a mixture of two compounds
Two different compounds floating about
Melting point
The temperature at which a solid changes into a liquid
Boiling point
The temperature at which a liquid changes into a gas
What are pure substances melting and boiling points like
Pure substances give sharp boiling and melting points (steep straight lines on graph)
What are impure substances melting and boiling points like
They do not have sharp melting/boiling points like pure substances because the different substances they contain melt or boil a different points (squiggly smooth curve on graph)
What does more impurity do
The greater amount of impurity the bigger the differences from the true melting point and boiling point and the higher the range
What does an impurity in a substance do to do it’s melting and boiling point
Lowers the melting point of a solid Raises the boiling point of a liquid
What is a formulation
A formulation is a mixture which has been designed as a useful product and is formed by mixing together several different substances and carefully measured quantities to ensure the product has the required properties