Properties of Matter

2.1 Classifying Matter  Why do we classify matter?  Different substance have different properties  How do we classify matter?  By their composition (Latin for “a putting together”)

Pure Substances  What is a pure substance?  Matter that always has the same composition  What are a few examples of pure substances?  Salt  Sugar

Pure Substance Continued  What can we say about the properties of pure substances?  They have the same properties  What are the categories of Pure Substances?  Elements  Compounds

Elements  What is an element?  Substance that cannot be broken down into simpler substances  How many are there?  About 100

Elements Continued  What is an atom?  The smallest piece of an element  Why do elements have fixed composition?  It only contains one type of atom

Examples of Elements  Aluminum – solid metal  Carbon – main element of life, used for writing  Oxygen – what we breathe  Nitrogen – inert gas, important ingredient for fertilizer

Symbols for Elements  One or two letters, first letter is always capital  Many symbols come from Latin names of elements, Au for gold stands for aurum

Compounds  What is a compound?  A substance that is made from two or more simpler substances.  What can compounds be broken down into?  Elements or smaller compounds

Properties of Compounds  Are they the same as the elements that make them?  No, for example water puts out fire, but Oxygen and Hydrogen are flammable  Is the composition of a compound fixed?  Yes, the parts always have the same proportions

Mixtures  What is a mixture?  Combination of multiple pure substances  Does a mixture have fixed composition?  No, the amounts of pure substances can vary

Types of Mixtures  How many types of mixtures are there? 22  What are the types called?  Heterogeneous  Homogeneous

Heterogeneous Mixtures  Hetero – from Greek, means different  Genus – from Greek, means kind  These mixtures are noticeably different

Homogeneous Mixtures  Homo – from the Greek, means “same”  This type of mixture has parts that cannot be distinguished from one another

Heterogeneous Mixture Homogeneous Mixture

Solutions  Solutions are formed when a substance dissolves in another substance and makes a homogeneous mixture  Example – tap water

Properties of Solutions  They do not separate into distinct layers over time  If you filter the solution, there will not be any particles that are trapped in the filter  Light can pass through them

Suspensions  Heterogeneous mixture that separates into layers over time  Filters can separate the parts

Colloids  Contains particles that are bigger than ones in solutions, so they don’t dissolve  Particles are smaller than suspensions, they don’t separate over time

Examples of Colloids Homogenized milk Fog