matter & properties of matter 8 th grade science

Matter & Properties of Matter8th Grade Science

What is Matter? Anything that has mass & takes up

space

Matter is either… Substance

Single kind of matter, fixed composition Examples: Table salt, sugar, baking soda,

or Not Substance More than a single kind of matter,

composition can change Examples: muffin mix (made up of

substance), flour, milk, eggs, fruit

Substance or Not Substance…?

Properties of Matter Physical properties are characteristics

that can be observed without changing the matter into another substance

Chemical properties are characteristics that describe the ability to change into another substance

Examples of Each Physical Properties

Water freezing to ice at 32°F Whether or not a substance dissolves in

water Texture Color

Chemical Properties Chemicals that are combustible vs. ones that

are not rusting

Elements Pure substance that cannot be broken

down into any other substances Everything is made up of a little more

than 100 elements Simplest substances

Particles of Elements Atoms are the particles of elements Atoms are made of even smaller

particles: A nucleus which is positively charged and

it is surrounded by a cloud of electrons (which have a negative charge).

Atoms

Chemical bonds When atoms combine they form

chemical bonds which is a force of attraction between two or more atoms. In many cases, atoms combine to

form larger particles called molecules.

Molecules are groups of two or more atoms held together by chemical bonds.

Examples: water, oxygen, and carbon dioxide.

Water Molecule(H2O)

Oxygen Molecule (O2)

Compounds Compounds are pure

substances made of two or more elements chemically combined into a fixed ratio.

A compound may be represented by a chemical abbreviation.

When two or more elements are placed together the result is a compound which has different characteristics than either of the original elements.

CalciumCarbonate

(Compound)(Shell of a snail)

Calcium(element)

Carbon(element)

Oxygen(element)

CaCO3

Made of two or more substances (elements, compounds, or both)

They are NOT chemically combined Can be separated physically Each substance in a mixture keeps its

individual properties Give some examples of mixtures

Salt water, soil, bag of marbles

What is a Mixture?

Heterogeneous MixturesA heterogeneous mixture is

when two or more substances are mixed but do not combine chemically to form a single substance.

Examples: salad, oil and water, rocks, chocolate chip cookie, chicken soup, etc. We can separate all the

components of the salad to the left, so it is a heterogeneous mixture.

Homogenous Mixture A homogeneous mixture is what

you have when you mix two or more substances together so that the composition is the same throughout the mixture.

Examples: sugar and water, brass (mixture of copper and zinc), air that we breathe (oxygen and nitrogen gases), soft drinks, milk, etc.

A solution is an example of an homogeneous mixture.

The two types of changes in matter

Physical changes: any change that alters the form or appearance of the matter, but does not alter the properties of the matter.

A substance that undergoes a physical change is still the same substance after the change.

Example: water exists as a solid, liquid, or a gas.

Chemical changes: any change which results in the production of one or more new substances is a chemical change.

The properties of the new substances are different than the properties of the original substances.

Example: Hydrogen peroxide turns into water and oxygen gas when it is used.

Law of the conservation of matter Simply stated that when matter changes either

chemically or physically, that matter is not created nor destroyed, it has just changed to another form or forms.

Example:CH4 (methane) + 2O2 (oxygen) =CO2 (carbon dioxide) + 2H2O (water)

Notice how the number of atoms did not change after the combustion.

Matter is neither created nor destroyed:Before the reactionCH4 (methane) + 2O2 (oxygen)

The total number of atoms before the reaction is:1 Carbon (C)4 Hydrogen (H)4 Oxygen (O)

After the reactionCO2 (carbon dioxide) + 2H2O (water)

The total number of atoms after the reaction is:1 Carbon (C)4 Hydrogen (H)4 Oxygen (O)