Matter – Properties and Changes

What is Matter?

Matter is anything that takes up space and has mass.

Mass is the amount of matter in an object.

Types of Matter

Matter

Pure Substance Mixtures

Elements Compounds Heterogeneous Homogeneous

Examples:

Properties

Words that describe matter (adjectives) Physical Property - a property that can

be observed and measured without changing the substance. Examples:

Chemical Property - a property that can only be observed by changing the type of substance. Examples:

Properties

Words that describe matter (adjectives) Extensive Property - depend on the

amount of matter Ex:

Intensive Property - only depend on the type of matter, not the amount Ex: Used to identify a substance

States of matter

Solid- matter that can not flow and has definite volume.

Liquid- definite volume but takes the shape of its container (flows).

Gas- a substance without definite volume or shape and can flow. Vapor- a substance that is currently a gas but

normally is a liquid or solid at room temperature.

States of MatterStates of Matter

Solid

Liquid

Gas

Definite Volume?

YES

YES

NO

Definite Shape?

YES

NO

NO

Expansion w/ Temp. increase

Small Expans.

Small Expans.

Large Expans.

Com-pressible?

NO

NO

YES

Solid Liquid Gas

Melt Boil

CondenseFreeze

Sublimation

Deposition

States of Matter

Plasma:

Occurs at high temperature low pressure

Formed when electrons separate from nucleus of gases

Most common state of matter in the universe

Changes in Matter

Physical Changes & Chemical Changes

These alter the appearance of matter without changing its composition. Examples?

Changes of the state (or phase) of matter is a physical change

The temperature & pressure at which matter changes phase are important physical properties These are melting & boiling points

Physical Changes

Another Way to Change States

Pressure For some substances it will turn solids to liquids

EX: Ice Skating

For others it will turn liquids to solids Ex: Silly Putty

Will turn gas to liquid Compressor in refrigerator and AC

Will turn gas to solid Formation of Dry Ice

Chemical Changes

Occur when one or more substances react and form a new substance

These are also called chemical reactions

Products of the chemical reactions ALWAYS have different properties than the original materials

Evidence of Chemical Reactions:

Formation of a gas Formation of a solid

precipitate Drastic color change Energy changes – temp. changes or

formation of light Exothermic vs. Endothermic Reactions

Change in the smell of a substance

Conservation of Mass

Mass can not be created or destroyed in ordinary chemical changes

All the mass can be accounted for Mass at the start = mass at end So the total mass of the products should

equal the total mass of the reactants

Antoine Lavoisier

Considered the father of modern Chemistry

Discovered the Law of Conservation of Mass (also called the Law of Conservation of Matter)

Did experiments on reactions.

Mixtures

A physical combination of two or more substances

Heterogeneous - you can see the individual substances that make it up. Ex: Chocolate chip cookie dough, gravel, soil.

Homogeneous- you cannot see the individual substances that make it up, it always has a single phase. Ex: Kool-aid, air.

Solutions

Another name for homogeneous mixture Can occur between any state of matter.

Examples: Liquid

Solid

Gas

Separating mixtures

Only physical changes - no new matter formed Filtration- separate solids from liquids with a barrier

Distillation- separate because of different boiling points Heat mixture Catch purified vapor in cooled area

Chromatography- different substances are attracted to paper or gel, so move at different speeds

Crystallization – pure solids form when solid particles come out of solution (make crystals)

Elements & Compounds

Section 3.4

Elements

Simplest pure substance Cannot be broken down into simpler matter by

normal physical or chemical means All one kind of atom Each one has a unique name and symbol. In

the symbol the first letter is always capitalized and the remaining letter(s) are lowercase.

There are 91 naturally occurring elements Who was given credit for organizing them into a

table? Dmitri Mendeleev

Compounds

Chemical combinations of two or more different elements

When they are broken down, the pieces have completely different properties than the compound. For example: Salt

Most of the substances we work with are compounds

Chemical Symbols

Used to write chemical formulas You know it is a formula because there will be

more than one capital letter Subscripts tell us how many of each atom in the

formula. H2O

C3H8

HBrO3

Laws of Compounds

By accounting for the mass of all matter there are a couple of laws that govern how compounds are created. Law of Definite Proportions

Law of Multiple Proportions

Law of Definite Proportions

Each compound has a specific ratio of elements by mass It is always a whole # ratio

For example – the chemical formula for water is always H2O

You can also see its ratio by mass: Water is always 8 grams of oxygen for each gram of

hydrogen

This does not change, no matter where you are on Earth! (Or in the universe for that matter)

Law of Def. Prop. Continued…

This law can be verified by determining the percent by mass of the elements in a compound:

Example: A compound contains 52.46 g of iron and 22.54 g of oxygen. What is the percent composition of oxygen?

30.05 % Oxygen

mass of elementPercent by mass (%) = 100

mass of compoundx

Law of Multiple Proportions

The textbook states that when the same elements combine to make different compounds, they combine in small whole number ratios.

You will NOT get fractions of elements Examples:

CuCl vs. CuCl2

CH4 vs. C2H6

Review

What makes a form of matter a substance? What are some examples?

How do you distinguish between chemical and physical properties?

What is the difference between a physical change and a chemical change? Give one example of each.

Why is a solution a homogeneous mixture? What is one way to separate a homogeneous mixture?

Explain how you would tell that NaCl is a compound but Na is an element.

Explain how all compounds obey the laws of definite and multiple proportions.