Chapter 17 Classification of Matter. Section 1: Composition of Matter.

Chapter 17

Classification of Matter

Section 1:

Composition of Matter

What you will learn…….

• How to define substances and mixtures• How to identify elements and compounds• How to compare and contrast solutions, colloids

and suspensions.

This is important because you can form a better picture of your world when you understand the

concepts of elements and compounds.

Teks Objective

• IPC (7) The student knows relationships exist between properties of matter and its components. The student is expected to:

• 7e:classify samples of matter from everyday life as being elements, compounds, or mixtures.

REMEMBER…..

• Matter- anything that takes up space and has mass.

Pure Substance

s

Mixtures

What are pure substances?

• Pure Substances– have a definite

composition – can be elements or

compounds.

Pure Substance

s

Elements Compounds

Pure Substance: ELEMENTS

– Elements• Are pure substances which CAN NOT be broken down

through physical or chemical means. • Composed of only one kind of atom- all atoms are the

same.

– You can find all the known elements on the Periodic Table of Elements.

Pure Substance: ELEMENTS• Examples of Elements:

– gold, silver, carbon, and hydrogen

ALL ATOMS ARE THE SAME!!!

GOLD- AuSILVER- Ag

Pure Substances: COMPOUNDS

• A compound is a pure substance composed of 2 or more elements that are chemically combined in definite proportions.

• Compounds DO NOT look or act like the elements that make them up.

SALT- Sodium Chloride: (NaCl)

Chlorine (Cl)- Green Gas

Sodium (Na)- Metal

WATER- H2O

Question?

How are elements and compounds related?

Answer…….

Compound contains 2 or more different elements

What are mixtures?

MIXTURES • composed of 2 or

more different substances that can be separated through physical means

• can be homogeneous or heterogeneous

Mixtures

Homogeneous

Heterogeneous

HOMOGENEOUS MIXTURES

• The composition is the same throughout

• Homogeneous mixtures are solutions, so the particles are so small that they CAN NOT be seen through a microscope

• Light passes through undisturbed

Examples: coke, alcohol, iron, pure air, vinegar

Vinegar

Coke

Question

What type of mixture is a solution?

Answer……

A homogeneous mixture

HETEROGENOUS MIXTURES• The composition is

NOT the same throughout – Examples: salad,

soil, gelatin

• Components can be observed.

• Can be classified as colloids or suspensions

Mixtures

Homogeneous

Heterogeneous Solutions

Colloids, Suspensions

HETEROGENEOUS MIXTURES: COLLOIDS

o Particles are not large enough to settle.

o Can be identified by using the Tyndall Effect

Shampoo

Gelatin

Tyndall Effect- Detecting Colloids

Scattering of light beam as it passes through a colloid.

Tyndall Effect- Detecting Colloids

The light from the headlights is scattered by fog.

The same colloid allows you to see the sunlight as it streams through the trees.

HETEROGENEOUS MIXTURES: SUSPENSIONS

• A liquid in which visible particles SETTLE.

Muddy Water - Some mud particles will fall to the bottom

and the water clears.

Orange Juice - Has to be shaken before drinking

because

SUMMARY

Mixtures

Homogeneous Heterogeneous

Solutions Colloids,

Suspensions

Pure Substances

Elements Compounds

Section 2:

Properties of Matter

Section 2: Properties of Matter

• Teks 8A: distinguish between physical and chemical changes

• 8C : investigate and identify the law of conservation of mass

You will learn…….

• How to identify substances using physical properties

• How to compare and contrast physical and chemical change

• How to determine how the law of conservation of mass applies to chemical changes

This is important because understanding the chemical and physical properties can help you use materials properly.

Physical Properties

Characteristics which can be observed without changing the chemical composition of the substance

Example - Physical Properties

• Appearance– Size– Texture– Shape– Color– State of matter

Example - Physical Properties

• Behavior - magnetic - can be drawn out into wires (copper)- pounded into sheets (gold) - ability to flow - Smell (odor)- density- melting point, boiling point, freezing point

Physical Change

• Change the appearance or state of a substance but NOT it's chemical make-up

• The identity remains the same

Examples: evaporation of water, melting of wax, dissolving of salt in water, breaking of glass

Question?

Does a change in state mean that a new substance has formed? Explain

Answer……

No the identity of the element or compound remains the same

Chemical Properties

• Are characteristics which depend upon the reaction with other materials.

– Examples: flammability, ability to rust, ability to react with water

Chemical Changeso Produce new substances that differ in

appearance and make-up from the original substance

o A change of one substance to another is a chemical change

Examples: burning, rusting , combustion, rotting, digestion

Rusting Burning Combustion

INDICATIONS THAT A CHEMICAL CHANGE MAY HAVE

OCCURRED.-production of a gas-permanent color change-formation of bubbles or solids in a liquid-production of heat and light

Gas PrecipitateColor Change

Weathering of Rocks by water

Physical or Chemical?

Answer……

Weathering can involve both physical and chemical change!

Question

What is a chemical change?

Answer……..

A change of one substance to another

THE LAW OF CONSERVATION OF MASS.

• Matter cannot be created or destroyed in a chemical or physical change.

– Example- If you burn a log, the ashes in the fireplace will be the same mass as the log

Video Time

• CREDITS• maxres.cgworks.com/gallery/ random/milk.jpg • www.mindspring.com/~audiolab/ brass.jpg • www.silvergen.com/ colloida2.htm • www.webshots.com/g/55/ nw-nw/31482.html • www.iop.org/Physics/Electron/ Exhibition/ • folding.stanford.edu/ education/water.htm • www.cla.sc.edu/mcks/html/exhib.htm• www.dprkorea-trade.com/metals/metals02.htm• www.psrc.usm.edu/macrog/sea/plant.htm • www.macdevcenter.com/.../2002/10/22/digi_photo_tips.htm • www.geocities.com/jeremyr46/ chemistry.htmlJanuary 20, 2003