Chemistry Unit 2 Part 1

Matter and Change Part 1 – Properties of Matter

TAKS student expectation
Integrated Physics and Chemistry (8) Science Concepts. The student knows that changes in matter affect everyday life . The student is expected to:
(A) distinguish between physical and chemical changes in matter such as oxidation, digestion, changes in states, and stages in the rock cycle; and
Here’s what you have to do if you want to pass this part of the TAKS:
Distinguish between physical and chemical properties.

Remember to duplicate
Sample Question Source: Spring 2003 Exit TAKS

Characteristics of a substance can be classified as physical properties or chemical properties. Which of the following is a chemical property?
A Boils at 56ºC
B Tastes sour
C Has a density of 2.9 g/cm3
D Reacts with acid to produce hydrogen gas
Sample Question Source: Reviewing Chemistry TAKS.

Properties and Changes in Matter
Every substance has characteristic properties.
Chemists use these properties to distinguish between substances and separate them.

Extensive vs. Intensive Properties Properties are either extensive or intensive .
Extensive Properties
depend on amount of matter present
volume, mass, and
amount of energy in a substance
Intensive Properties
do not depend on amount of matter present
melting point, density, ability to conduct electricity, and percent composition

Properties of One Penny
Properties
Metal
Composed of 2.5% copper and 97.5% zinc
Mass – 2.50 grams
Volume – 0.442 mL
Density – 5.66 g/mL

Properties of Many Pennies
Properties
Metal
Composed of 2.5% copper and 97.5% zinc
Mass – 2500 grams
(1000 pennies x 2.5 g)
Volume – 442 mL
(1000 pennies x.442mL)
Density – 5.66 g/mL
One Thousand Pennies

Extensive vs. Intensive Properties
WHICH PROPERTIES REMAINED THE SAME?
Metal
Percent Composition
Density
The intensive properties remained the same because they do not depend on the amount of pennies present.

Extensive vs. Intensive Properties
WHICH PROPERTIES CHANGED?
Mass
Volume
The extensive properties changed because they do depend on the amount of pennies present.

Property Types
There are 2 major categories that all properties of matter fall into
Physical Chemical

Physical Properties
Physical properties are characteristics that can be observed or measured without changing the identity of a substance.
They can be observed by using the five senses.

Physical Properties
Cross between a lab and a poodle
Size of a lab
With the curly hair of a poodle
Can be black, yellow, brown, or white
Tail of a lab
What are the physical properties of a labradoodle?

Chemical Properties
Chemical properties relate to a substance’s ability to undergo changes that transform it into different substances.

Examples of chemical properties:
Conductivity -ability to conduct electricity
Flammability – ability to ignite
Electronegativity – the ability to retain electrons

Density – a Property of Matter
Density – a ratio that compares the mass of an object to its volume. The density of every pure substance in the world is unique.

Calculating Density
The formula for calculating density is given on your TAKS formula chart, so you must know how to use it

Sample Question Source: Grade 11 TAKS Information Book

Remember to duplicate

Sample Question Source: Spring 2006 10th TAKS

Part 2 – Changes in Matter

Physical Change
A change in the physical appearance of a substance that does not change the identity of the substance.
LIQUID SOLID GAS

Physical Changes
Phase Change – physical change from one state to another
LIQUID Between 0°C and 100 0°C SOLID Below 0°C GAS Above 100°C Only the temperature changes Still H 2 O in every form!!!

Physical Changes
Examples of physical changes:
Crushing an aluminum can
Cutting your hair
Shredding paper

Chemical Changes
Chemical changes, or chemical reactions, occur when one or more substances is converted into another substance.
Original atoms are preserved
New substances are formed
Different chemical composition than original substance

Chemical Changes
Chemical changes are chemical reactions.
Indicated by a number of signs
formation of a gas,
formation of a solid, or precipitate
change in temperature
evolution of heat and light
Change in color
Change in odor

Chemical Changes
When iron (Fe) rusts, you can see it happen over a long period of time.
The actual iron molecules change their structure as they react with oxygen and are oxidized.

Chemical Changes
Examples of chemical changes:
Milk souring
Grass growing
Frying an egg

Energy Transfer
All changes (physical and chemical) involve some transfer of energy.
Body uses energy from chemical reactions to digest food.
Weather involves a transfer of energy to evaporate water in the atmosphere.
Therefore, the study of matter also involves the study of energy.

Summary
Extensive Properties
Intensive Properties
Physical Properties and Changes
Chemical Properties and Changes
Transfer of Energy

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Chemistry Unit 2 Part 1

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