properties and changes

Physical and Chemical

Properties of Matter

What is a physical property of matter?

• A property that can be observed or measured without changing the identity of that matter

• Ex: Color, odor, shape, size, etc.

Thermal Conductivity

Definition:

The ability to transfer thermal energy (heat) to something else

Example:

Coffee in a special cup to prevent heat transfer to our hands

State

Definition:

The form in which matter exists: solid, liquid, gas, or plasma

Example:

Ice = Solid Water = Liquid Helium = Gas Lightning = Plasma

Malleability

Definition:

The ability to be pounded into thin sheets

Example:

Aluminum can be pounded flat to make aluminum foil

Ductility

Definition:

The ability to be drawn into thin wires

Example:

Copper is used to make wires

Example:

Alka-seltzer dissolves in water or sugar dissolves in coffee

Solubility

Definition:

The ability for one substance to dissolve into another substance

Density

Definition:

Mass per unit volume

Example:

Lead is used for fishing weights because it is more dense than water

More information about density...

Density = The amount of matter in a given space or volume

Density = m Mass v Volume

More information about density...

Most substances have a unique density:Water = 1.00 g/mLGold = 19.32 g/mL(See page 13 in your book for a bigger list)

Density < 1 - The object will float in water Density > 1 – The object will sink in water

The Magic Triangle

Answers are expressed in g/cm3

or g/mL

CHEMICAL PROPERTIES

Chemical properties can ONLY be observed AS the substances are changing into different substances.

FLAMMABILITY: A material’s ability to BURN in the presence of OXYGEN

REACTIVITY:How readily (easily) a substance combines chemically with other substances.

Physical and Chemical Changes

Physical changes are those changes that do not result in the production of a new substance.  If you melt a block of ice, you still have H2O at the end of the change.   

Physical Changes

• Physical changes do not result in the formation of a new substance and are reversible.

• The following are examples of physical changes:• Melting and freezing• Boiling and condensation• Forming a separable mixture

If you break a bottle, you still have glass.  Painting your nails will not stop them from being fingernails.  Some common examples of physical changes are: melting, freezing, condensing, breaking, crushing, cutting, and bending.

Some, but not all physical changes can be reversed. You could refreeze the water into ice, but you cannot put your hair back together if you don’t like your haircut!

Special types of physical changes where any object changes state, such as when water freezes or evaporates, are sometimes called change of state operations.

Chemical changes, or chemical reactions, are changes that result in the production of another substance. 

Chemical Changes Chemical changes result in the formation of

a new substance and tend to be irreversible.

The following observations often suggest that a chemical change has taken place:

Colour change Evolution (release) of gas Temperature change Solution turns cloudy Change of pH

Signs for chemical changes

Color change Gas formation (fizzing/bubbles) Change in light and temperature Precipitate (solid formation)

When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon.  When you light your Bunsen burner in lab, you are carrying out a chemical CHANGE that produces water and carbon dioxide. 

Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning, and decomposition. 

Physical or Chemical Change?

Painting WoodPHYSICAL

Physical or Chemical Change?

•Burning Paper•CHEMICAL

Physical or Chemical Change?

•Digestion of food•CHEMICAL

Physical or Chemical Change?

•Sugar dissolving in water

•PHYSICAL

Physical or Chemical Change?

•Iron turning red when heated

•PHYSICAL

Physical or Chemical Change?

•Evaporation•PHYSICAL

Physical or Chemical Change?

•A pond freezing in winter

•PHYSICAL

Physical or Chemical Change?

•Melting ice•PHYSICAL

Physical or Chemical Change?

•Cutting wire•PHYSICAL

Physical or Chemical Change?

•Painting fingernails•PHYSICAL

Physical or Chemical Change?

•Cutting fabric•PHYSICAL

Physical or Chemical Change?

•Baking muffins•CHEMICAL

Physical or Chemical Change?

•Shattering glass•PHYSICAL

Physical or Chemical Change?

•Decomposition of old leaves

•CHEMICAL

Physical or Chemical Change?

•Wrinkling a shirt•PHYSICAL

Physical or Chemical Change?

•An old nail rusting•CHEMICAL