2.1 What is Matter?

2.2 Properties of Matter

2.3 Changes in Matter

2.1 What is Matter?

Key Terms

Chemistry Matter

Element Atom

Compound Molecule

Chemical Formula Pure Substance

Mixture

2.1 What is Matter?

What Is Matter?

Chemistry is an important part of our every day life. It is important, because chemistry is related to everything we use

Composition of Matter

2.1 What is Matter?

Matter is anything that has mass and

takes up space

An element is a substance that cannot be separated or broken down into simpler substances by chemical means.

2.1 What is Matter?

Atom - smallest unit of an element that maintains the properties of that element

Each element is represented by one or two letters that are used world wide

Each of the more that 110 elements have different properties from the rest

2.1 What is Matter?

Elements combine to form compounds which have unique properties. Every compound is different from the elements that it contains. When the elements combine they are in the same proportions

Individual atoms can join together to form molecules. Molecules are the smallest unit of a substance that behaves like the substance.

2.1 What is Matter?

Most molecules are made up of different elements. However, molecules can also be made up of the same element

What is the difference between a compound and a molecule?

Compounds are made up of atoms of two or more different elements, and a molecule may be made up of the same elements or different elements.

2.1 What is Matter?

How do we represent compounds and molecules?

By using chemical formulas

Chemical formulas show how many atoms of each element are in a unit of a substance

2.1 What is Matter?

The number of atoms for each element is shown as a subscript number. A number placed in the front of a chemical formula shows the number of molecules.

Pure Substances and Mixtures

2.1 What is Matter?What is a pure substance?

a sample of matter, either a single element or a single compound, that has definite chemical and physical properties.

A mixture is the combining of pure substances that are not chemically combined

2.1 What is Matter?

How are mixtures classified?

By being heterogeneous or homogenous

Homo “same” mixture appears same throughout

Hetero “different” mixture which differences are seen

2.1 What is Matter?

A mixture can also be miscible or immiscible

Miscible - compounds are dissolved in one another (gasoline)

Immiscible - compounds separate (water and oil)

2.1 What is Matter?

Gases can mix with liquids

Think about Coke and Pepsi what makes them fizz?

Carbon dioxide that is dissolved in the water.

2.2 Properties of Matter

Key Terms

Melting Point

Boiling Point

Density

Reactivity

Flammability

2.2 Properties of Matter Physical Properties

These are the properties that give matter its color and shape

What are some other types of physical properties?

VolumeMassDensity

2.2 Properties of Matter

Matter can also be described in terms of the absence of a physical property

Other physical properties that can be used to describe matter are melting and boiling points

A characteristic of a pure substance is that its physical properties remain the same or constant

2.2 Properties of Matter

For water - at sea level water freezes at 0 degrees Celsius and boils at 100 degrees Celsius

There are three common states of Matter

1. Solid

2. Liquid

3. Gas

2.2 Properties of Matter

The states of matter go from a state of order (solid) to a state of disorder (gas)

Density is also a physical property

Density = mass (g)/ volume (cm cubed)

2.2 Properties of Matter

low density = light

high density = heavy

Weight and density are different

What is density used for?

determine if an object will sink or float

2.2 Properties of Matter

Chemical Properties

One way to determine the chemical properties of matter is by how well it reacts with other elements

Reactivity - the ability of a substance to combine chemically with another substance

2.2 Properties of Matter

Flammability - the ability to burn

A substance always has its chemical properties, even when you cannot observe them

Comparing Physical and Chemical Properties

2.2 Properties of Matter

Physical - can observe without changing the identity of the substance

Chemical - observed only in substances in which the identity of the substance changes

2.2 Properties of Matter What are characteristic properties?

properties that are most useful in identifying a substance

1. Density

2. Solubility (whether or not it dissolves)

3. Reactivity with acid

2.2 Properties of Matter

These properties are always the same whether the sample is large or small

2.3 Changes in Matter

Key Terms

Physical Change

Chemical Change

2.3 Changes in Matter

The physical and chemical properties of a substance determines how the substance behaves under different conditions

Physical Change

2.3 Changes in Matter

What are physical changes?

A change of matter from one form to another without a change in chemical properties

2.3 Changes in Matter

During physical changes, energy is absorbed or released. The atoms that make up the substance are not changed

What kind of change takes place when sugar is mixed with water?

Physical - dissolving is a physical change.

2.3 Changes in Matter

Since mixtures are not chemically combined, each component of a mixture has the same chemical makeup it had before the mixture was formed

All substances in a mixture can be separated out of the mixture

2.3 Changes in Matter

Chemical Changes

A chemical change occurs when a substance changes composition by forming one or more new substances

The new substances have different properties

2.3 Changes in Matter

How can chemical changes be detected?

By change in odor or color are two examples of how chemical changes are detected

2.3 Changes in Matter

Chemical changes can not be reversed by physical changes. However, some chemical changes can be changed under the right conditions or other chemical changes.

Some compounds can be broken down into elements through chemical changes.