1. Elements

2. Elements, The Simplist Substance
A pure substance that cannot be broken down into simpler substances by physical or chemical means.
Pure Substance:
Substance in which there is only one type of particle
Each element contains only one type of particle (atoms)

3. Properties of Elements
Each element has its own characteristic properties that will help identify the element.
Physical properties
Boiling point
Melting point
Density
Chemical properties
Reactivity
Flammability
Elements may share similar properties, but have other properties that will identify the substance.

4. Classifying Elements by Their Properties
Categories of Elements:
Metals: (Most Elements)
Shiny
Conduct heat energy and electric current
Iron, nickel, cobalt
Nonmetals:
Dull (solid)
Do not conduct heat energy and electric current
Carbon, sulfur, iodine
Metalloids:
Properties of both metals and nonmetals

5. Compounds
Compound:
Substance that is composed of two or more elements that are chemically combined.
Combine by reacting (reactivity; chemical property)
Made up of molecules
Formed when atoms of 2 or more elements join
Elements join in a specific ratio according to their masses to form a compound
A ratio of a certain compound is always the same.
Hydrogen to oxygen 1:8 to form water.

6. Properties of Compounds
May be identified by both physical and chemical properties.
Properties of compounds differ from those of the elements that form them.
Ex: Sodium Chloride (Table Salt)
Sodium reacts violently with water
Cholorine is a poisonous gas
Properties: Compounds vs. Elements

7. Breaking Down Compounds
Some compounds may be broken down into elements by chemical change.
Some break down into simpler compounds.
Carbonic Acid breaks down into carbon dioxide and water.
Break down through chemical change
Need energy
Heat
Electric current (electrolysis)
Methods of Breaking Down Compounds

8. Compounds in Your World
Food
School Supplies
Clothes
Compounds found in nature usually need to be broken down for use in industry.
Aluminum – produced by breaking down aluminum oxide
Ammonia - nitrogen + hydrogen
Proteins are compounds found in living things
Need the element nitrogen to make proteins
Carbon Dioxide is needed by plants to produce carbohydrates
Produce energy for plants and animals
Compounds in Industry
Compounds in Nature