PSc.2.1 OBJECTIVE: Understand types, properties and structure of matter.

PSc.2.1 OBJECTIVE: Understand types, properties and structure of

matter.

Objectives

PSc.2.1.1–Classify matter as: homogeneous

or heterogeneous; pure substance or mixture; element or compound; metals, nonmetals or metalloids; solution, colloid or suspension.

SHOE CLASSIFICATION ACTIVITY

3

Matter Flowchart

MATTERCan it be

physically separated?

Homogeneous Mixture

(solution)

Heterogeneous Mixture

Compound Element

MIXTURE PURE SUBSTANCE

yes no

Can it be chemically

decomposed?

noyesIs the composition

uniform?

noyes

Colloids Suspensions

Homogeneous vs Heterogeneous

If matter is not uniform throughout, then it is a heterogeneous.

If matter is uniform throughout, it is homogeneous.

Homogeneous Matter

Salt water, apple juice and dust free air (mixture of nitrogen, oxygen, argon, carbon dioxide, water vapor and other gases) are examples of homogeneous materials.

Homogeneous Matter

Brass (solid mixture of copper and zinc) is also homogeneous.

Brass is an alloy, which is a mixture of metals.

Heterogeneous Matter

Oil-and-vinegar salad dressing, which has a layer of oil floating on a layer of vinegar, is heterogeneous.

Homogeneous vs. Heterogenous Matter

Classify the following substances and mixtures as either homogeneous or heterogeneous.

Flat soda pop, cherry vanilla ice cream, salad dressing, sugar, soil, aluminum foil, black coffee, sugar water, city air, paint, alcohol, iron, beach sand, pure air, spaghetti sauce.

10

Homogeneous vs. Heterogeneous Matter

Homogeneous Sugar Aluminum foil Black coffee Sugar water Alcohol Iron Pure air

Heterogenous Flat soda pop Cherry vanilla ice cream Salad dressing Soil City air Paint Beach sand Spaghetti sauce

11

Pure Substances

A pure substance always has the same composition.

Pure substances are either elements or compounds.

Elements are substances that cannot be broken down into other substances chemically or physically.

Examples include sodium, carbon and gold.

Elements

Elements

Elements– composed of identical atoms– Ex: copper wire, aluminum foil

Compounds

Compound

– composed of 2 or more elements in a fixed ratio

– properties differ from those of individual elements

– Ex: table salt

Another example of a compound includes water (hydrogen and oxygen).

Compounds

Mixtures

A mixture can be defined as something that has variable composition.

Soda is a mixture (carbon dioxide is dissolved in it), and coffee is a mixture (it can be strong, weak or bitter).

Heterogeneous Mixtures

A heterogeneous mixture contains regions that have different properties from those of other regions.

When we pour sand into water, the resulting mixture contains two distinct regions.

Homogeneous Mixtures

Homogeneous mixtures (also known as solutions) are mixtures in which the composition is uniform, there are no chunks or layers.

Substances vs. Mixtures

Classify the following as to whether it is a substance or a mixture.

Sodium, water, soil, coffee, oxygen, alcohol, carbon dioxide, cake batter, air, soup, iron, salt water, ice cream, nitrogen, eggs, blood, table salt, nail polish, milk, cola

20

Substances vs. Mixtures

Substances Sodium (Na) Water (H2O) Oxygen (O2) Alcohol (CxHyOH) Carbon Dioxide (CO2) Iron (Fe) Nitrogen (N2) Table Salt (NaCl)

Mixtures Soil Coffee Cake batter Air Soup Salt water Ice cream Eggs Blood Nail polish Milk Cola

21

Identification Activity

Classify the contents of each bag as an element, compound, or mixture.

Justify your answers.

22

Pure Substances and Mixtures

A. gasoline

B. copper metal

homogeneous mixture

pure substance

Classify each of the following as a pure substance, a homogeneous mixture or a heterogeneous mixture.

Question

C. a stream with gravel at the bottom

D. chunky peanut butter

heterogeneous mixture

heterogeneous mixture

Classify each of the following as a pure substance, a homogeneous mixture or a heterogeneous mixture.

Question

E. a multivitamin tablet

F. carbon dioxide gas

homogeneous mixture

pure substance

Classify each of the following as a pure substance, a homogeneous mixture or a heterogeneous mixture.

Question

Tyndall Effect

The Tyndall Effect is light scattering by particles in a colloid or particles in a fine suspension.

Tyndall Effect

The Tyndall Effect is shown on the left.

28

Solution Colloid Suspension

type

particle size

Tyndall Effect

“Settle out”

Example

Mixtures

Solution– homogeneous– very small particles– no Tyndall effect– particles don’t settle– Ex: rubbing alcohol

Colloid– heterogeneous– medium-sized

particles– Tyndall effect– particles don’t

settle– Ex: milk

Mixtures

Suspension– heterogeneous– large particles– Tyndall effect– particles settle– Ex: fresh-

squeezed lemonade

Mixtures

A) mayonnaisecolloid

Question

Classify each of the following as a solution, colloid or suspension.

suspension

B) muddy water

C) fogcolloid

Question

Classify each of the following as a solution, colloid or suspension.

solution

D) salt water

E) Italian salad dressing

suspension

Question

Classify each of the following as a solution, colloid or suspension.