chapter 17 classification of matter. section 1: composition of matter
TRANSCRIPT
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
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