Classification of MatterChapter 18

Composition of MatterSection 1

Pure Substances

• Pure Substances

• A type of matter with a fixed composition

• Examples

• Helium

• Aluminum

• Water

• Salt

Elements

• All substances are made of atoms

• If all the atoms have the same identity, the substance is an element

• There are approximately 90 naturally occurring elements

• Helium, Copper, Oxygen, Gold

• More than 20 more are made in labs

• Americium, Nobellium

Compounds

• Compound

• Two or more different elements combined in a fixed proportion

• Water (H2O)

• Glucose (C6H12O6)

• Carbon dioxide (CO2)

• Compounds will have properties different than the properties of the individual elements that make it up

• Na+ (very reactive solid)

• Cl- (poisonous gas)

• Salt (NaCl) edible salt

Molecules

• Molecules

• A particle consisting of two or more atoms that are bonded together chemically

• All molecules are compounds, but not all compounds are molecules

• O2 is a molecules but not a compound

Mixtures

• Mixture

• A material made up of two or more substances that can be easily separated by physical means

• Pizza

• Soda

• Orange Juice

• Dyes

• Do not always contain the same proportions of substances that make them up

Mixtures

• Heterogeneous Mixtures

• The materials can be distinguished easily

• Granite

• Trail Mix

• Dry Soup Mixes

• Poly-cotton Fabrics

Mixtures

• Homogenous mixture

• Contain two or more gaseous, liquid, or solids blended evenly together

• Vinegar

• Soft drinks in sealed bottles

• Blood

• Solutions are homogenous mixtures of particles so small that they cannot be seen with a microscope and won’t settle out

Mixtures

• Colloids

• Mixture containing components in varying proportions (heterogenous)

• Won’t settle when left standing

• Fog

• Milk

• Paint

• Colloids can be identified by passing a beam of light through them

• A light beam can pass through a solution, but not through a colloid

Mixture

• Suspensions

• Neither solution or colloid

• Particles are temporarily suspended, but will eventually settle out

• Pond water

Comparing Solutions, Colloids, and Suspensions

Comparing Solutions, Colloids, and Suspensions

Description Solution Colloids Suspension

Settle upon standing? No No Yes

Separate using filter paper?

No No Yes

Particle Size 0.1 – 1nm 1 – 1,000 nm >1,000 nm

Scatter Light? No Yes Yes