ch2.1 (properties of matter) - tracy unified school district 2 notes... · properties of matter ......

Ch 2.1 (Properties of Matter)

matter

• Anything that has mass and

takes up space is matter

http://www.chem4kids.com/files/matter_intro.html

Properties of matter

• Matter is described by two types of properties;

• 1. Physical Properties

• 2. Chemical Properties

Physical Properties—describe matter

Properties that are observed without changing the matter.

• Melting and boiling point are physical properties (the temperature at which a substance melts or boils)

• State of matter is also a physical property (solid, liquid, gas)

• Density ( a measure of how closely packed an object’s atoms are)

• http://www.harcourtschool.com/activity/hotplate/index.html

Chemical Properties

• Chemical property is the ability of matter to change into different

matter.

• Chemical changes change the chemical nature and properties of

substances to form new substances

• A match burns

• Two substances mix together turn a color different from either of them

• Toasting marshmallows

• Melt it—physical change

• Burn it—chemical change

atom

• The smallest particle that can

still be identified as the

matter it came from is an

atom

element

• Matter that is made of only

one kind of atom is an

element.

• Carbon, hydrogen, and

oxygen are all elements.

• The picture is of the element

zinc in hydrogen chloride.

Zinc + HCL

Difference between

COMPOUND & MIXTUREMIXTURE COMPOUND

1. A mixture can be separated into its particles by physical processes (filtration, evaporation, sublimation, distillation)

1. A compound cannot be separated into its constituents by physical processes. It can be separated by chemical means

2. Elements can combine in any ratio.

3. Elements do not react chemically.

4. Mixture shows the properties of its constituents

2. Elements combine in a fixed ratio.

3. Elements react chemically and make new substance.

4. A compound has new properties different from its constituents.

� CH 2.2

�(Changes in Matter)

Physical change-a change in state

• The substance is still

the same substance

• Form changes but

chemical makeup

doesn’t

Ice changes to water—

water changes to ice,

frozen water is still water

Water changes to steam, a gas, when it is heated to its boiling point,water vapor

condenses to form a liquid

Changing States of Matter-Water

• Water freezes at 0 degrees Celsius, 32 degrees Fahrenheit

• Water boils at 100 degrees Celsius, 212 degrees Fahrenheit

• http://www.chem4kids.com/files/matter_chemphys.html

Other Physical Changes

• Breaking

• Crushing

• Cutting

• Bending

• Melting

• Freezing

• Boiling

• Can happen naturally

• People can cause

changes

– Water evaporating

– Rain falling and

causing puffles

– People cause change

• Recycling paper

• Recycling metal

Chemical Properties and Changes

• Chemical changes change the chemical nature and properties of substances to form new substances

– A match burns

– Two substances mix together turn a color

different from either of them

– Toasting marshmallows

• Melt it—physical change

• Burn it—chemical change

Combustibility-a measure of how

easily a substance will burn, or

combine rapidly with oxygen

• Corrosion of metal—when iron combines with oxygen in the air, rust forms

• Gas bubbles—hydrogen peroxide on a cut

• A change in color--fireworks

Energy

• Physical and chemical changes are

accompanied by energy changes.

• energy: the capacity to do work

• work: results from a force acting on a distance

Energy Conversions

• The Law of

Conservation of

Energy states that

energy is neither

created nor destroyed.

• Energy can change

from one form to

another or transferred

from one object to

another.

Temperature and Heat

• Temperature is the measure of the thermal energy of a substance.

• The hotter an object, the greater the motion of its particles, and the greater the thermal energy.

• Heat is the transfer or exchange of thermal energy caused by a temperature difference.

Thermal Energy

• Atoms and molecules of matter are in constant, random motion, which is the source of thermal energy.

• More motion = more thermal energy.

• Is there a way to easily measure this motion?