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

Objectives  PSc – 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 MATTER Can it be physically separated? Homogeneous Mixture (solution) Heterogeneous Mixture CompoundElement MIXTUREPURE SUBSTANCE yesno Can it be chemically decomposed? noyes Is the composition uniform? noyes ColloidsSuspensions

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  Iron  Pure air  Alcohol  Flat soda pop Heterogenous  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)  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  Alcohol 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 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

Quiz 1. _____ has mass and occupies space. 2. Elements _____ be broken down into simpler substances. 3. Pure substances include _____ and _____. 4. The formula H 2 O formula represents a _____ of water. 5. Mixtures are formed from _____ substances. 27

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.

29 SolutionColloidSuspension 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) mayonnaise colloid Question Classify each of the following as a solution, colloid or suspension. suspension B) muddy water

C) fog colloid 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.

Quiz 1. A difference in what physical property is often used to separate two immiscible liquids? 2. Fog and smoke are examples of what type of heterogeneous mixture? 3. What is another term for a homogeneous mixture? 4. What is an alloy? 36

Quiz 1. The temperature at which a solid becomes a liquid. 2. Ability of a substance to burn in the presence of oxygen. 3. Ability of a substance to combine chemically with another substance. 4. Mass per unit volume of a substance. a. Melting point b. Boiling point c. Density d. Reactivity e. Flammability 37