Classification of Matter by Composition PDF

# Classification of Matter by Composition ## Erbil Polytechnic University - Shaqlawa Technical Institute - Medical Lab. Technology Dept. - LEC. 3 ## Classification of Matter by Composition **Matter whose composition does not change from one sample to another is called a pure substance** - Made o...

# Classification of Matter by Composition ## Erbil Polytechnic University - Shaqlawa Technical Institute - Medical Lab. Technology Dept. - LEC. 3 ## Classification of Matter by Composition **Matter whose composition does not change from one sample to another is called a pure substance** - Made of a single type of atom or molecule - The composition of a pure substance is always the same. Therefore, all samples of the same substance will have the same characteristics **Matter whose composition may vary from one sample to another is called a mixture** - Two or more types of atoms or molecules combined in variable proportions. - Different samples will have different characteristics due to varying composition. ## Classification of Matter by Composition | No | Matter | Variable composition? | |:-----------:|:--------------------:|:---------------------:| | Pure Substances | Yes | No | | Mixture | Yes | Yes | ### Pure Substances - Made of one type of particle - All samples show the same intensive properties ### Mixture - Made of multiple types of particles - Samples may show different intensive properties ## Classification of Pure Substances - Elements **Pure Substances that cannot be decomposed into similar substances by chemical reactions are called elements** - Decomposed means broken down - Basic building block of matter - Composed of a single type of atom - Atoms may or may not be combined into molecules. ## Classification of Pure Substances - Compounds **Pure substances that can be decomposed are called compounds** - Chemical combinations of elements - Composed of molecules that contain two or more different kinds of atoms - All molecules of a compound are identical, so all samples of a compound behave the same way - Most natural pure substances are compounds. ## Classification of Pure Substances | No | Separable into simpler substances? | |:-------------:|:--------------------------------:| | Pure Substances | Yes | | Element | No | | Compound | Yes | - **Element** – Made of one type of atom(some elements are found as multi-atom molecules in nature). - **Compound** – Made of one type of molecule, or an array of ions. Units contain two or more different kinds of atoms. - **Compounds** combine together to make compounds ## Classification of Mixtures **Homogeneous mixtures are mixtures that have uniform composition throughout** - Every piece of a sample has identical characteristics, though another sample with the same components may have different characteristics. - Atoms or molecules mixed uniformly. **Heterogeneous mixtures are mixtures that do not have uniform composition throughout** - Regions within the sample can have different characteristics. - Atoms or molecules are not mixed uniformly. ## Classification of Mixtures | No | Uniform throughout? | |:---------------:|:---------------------:| | Mixture | Yes | | Heterogeneous | No | | Homogeneous | Yes | - **Heterogeneous** – Made of multiple substances, whose presence can be seen. Portions of a sample have different composition and properties - **Homogeneous** – Made of multiple substances, but appear to be one substance. All portions of a sample have the same composition, properties, and can be distributed evenly. ## Changes in Matter **Changes that alter the state or appearance of the matter without altering the composition are called physical changes** **Changes that alter the composition of the matter are called chemical changes** - During a chemical change, the atoms that are present rearrange into new molecules but all of the original atoms are still present ## Physical Changes in Matter - The boiling of water is a physical change. Water molecules are separated from each other but their structure and composition do not change. - The water molecules change from liquid to a gaseous state, which is a physical change. ## Chemical Changes in Matter - The rusting of iron is a chemical change. The iron atoms in the nail combine with oxygen atoms from $O_2$ in the air to make a new substance, rust, with a different composition. ## Properties of Matter **Physical Properties** are the characteristics of matter that can be changed without changing its composition - Directly observable **Chemical Properties** are the characteristics that determine how the composition of matter changes as a result of contact with other matter or the influence of energy - Describe the behaviour of matter ## Common Physical Changes - **Processes that cause changes in the matter that do not change its composition** - **State changes:** - Boiling/condensing - Melting/Freezing - Subliming - **Dissolving** ## Common Chemical Changes - **Processes that cause changes in the matter that change its composition** - Rusting - Burning - Dyes fading or changing color