CHAPTER 2Properties 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

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 milkFog