More about Matter

Use the information on these slides to check and improve your organization of matter.

Is Air matter?

• What are the two criteria for matter?

–Takes up space

–Has mass

What is NOT Matter?

•Energy!

What is the composition of matter?

Matter

Pure Substance

Mixture

What is a pure substance?

• A pure substance has a definite composition (chemical formula).

• The composition of a substance will have the same percent of elements no

matter where the sample was obtained. – Water from the Cuyahoga River and water

from the Pacific Ocean (once cleaned up) will have the same ratio of hydrogen to oxygen.

– Oxygen here is the same as in Columbus

What is a pure substance?

• A pure substance, by definition, is an element or a compound.

• Water is a compound, and thus a pure substance.

Pure Substance

Pure Substance

Element Compound

What is an element?

• a pure substance made of only one kind of atom

• An atom is the smallest unit of an element that maintains the properties of that element.

Element

Atom

Elemental Samples

• Zinc, copper, lead, carbon, sulfur…anything on the periodic table

What is a compound?• a substance that is made from the atoms

of two or more elements that are chemically bonded

• has a definite chemical formula• cannot be broken down any farther by

simple physical means• smallest amount of a compound with all

the properties is a molecule

What is a compound?

• A molecule is the smallest unit of a compound.

Compound

Molecule

Examples of compounds?

• Carbon dioxide CO2

• Water H2O• Sugar C6H12O6

• Oxygen O2

• Table salt NaCl

• 1 molecule of table salt is the smallest amount that is still table salt. Can’t break it down any farther by physical means…

What is the composition of matter?

Matter

Pure Substance Mixture

Mixture

• A mixture is made up of two or more substances that are not chemically combined.

• Mixtures can be separated by simple physical means.

• e.g. sand and salt, salad

Mixtures

• Two mixtures containing the same substances may not have the same proportions.

• Example: not all salads have the same amount of tomatoes, but they are all salads

Water and Food Coloring Mixture

• Two mixtures of the same substances may have different proportions.

Mixtures

Mixtures

Homogeneous Heterogeneous

Homogeneous Mixture• Homogeneous mixtures are uniform

in composition, i.e. particles are evenly spread throughout and you can’t see any differences

• They have the same proportion of components throughout.

Examples:- Salt water - Sugar water- Air - Carbonated water

Solution

• A homogeneous mixture when two or more substances are evenly distributed in one another.

Alloy

• A solid or liquid mixture of two or more metals (e.g. brass, bronze)

• Is a solution, because particles are evenly spread

Homogeneous Mixture

Solution Alloy

Heterogeneous Mixture

• Heterogeneous mixtures are not uniform throughout; you can see differences

• Molecules are not evenly spread

• If the particles settle over time, it’scalled a suspension (if they

don’t settle, it’s called a colloid)

What is a suspension?

• A mixture in which particles settle over time.

• Examples: Orange juice with pulp and muddy water

Heterogeneous Mixture

Suspensioncolloid

Working backwards...4 examples

MatterPure substance

Mixture

element compound

homogeneous heterogeneous

atom moleculesolution alloy suspension

Italian salad

dressing

brassgold

black coffee

What is a colloid?

• A heterogeneous mixture suspension where the particles are small enough not to settle.

• May appear to be the same throughout but it is not!

• Examples: -Fog -Jello-Paint -Smoke-Whipped cream -Marshmallow

Tyndall Effect

• Sometimes the particles are too small to see.

• Light does not pass through colloids because their particles scatter light.

• This is called the Tyndall Effect.

What is an emulsion?

• A special case of a colloid

• A mixture of two immiscible liquids (ones that usually don’t mix)

• Examples: mayonnaise, butter, whole milk