Create foldable with three flaps on one side and four on the other.

Physical and Chemical Changes

Review Matter: anything that has mass and takes up space Energy: ability to do work or cause change – Energy is used anytime a change in matter occurs

Kinds of Matter The fundamental kinds of matter interact to form everything around us. They are: – elements – compounds – mixtures

Elements Elements are substances that cannot be broken down into other substances chemically or physically Examples: – sodium – oxygen – carbon – aluminum

Compounds Compounds are substances made of two or more elements combined chemically Compounds have properties different from those of the original elements Examples: – Water: hydrogen and oxygen – Table salt: sodium and chlorine

Mixtures Mixtures are a combination of two or more substances that are not chemically combined. They can be separated again. examples – salad – frosted cake – kool-aid

Properties of Matter Property: characteristic There are two kinds of properties for matter: – Physical properties – Chemical properties physical and chemical properties are used to identify, describe, and classify matter

Physical Properties Observe physical looks of something Also observed without changing the substance into something else Examples: – Color – Density – Shape – Boiling Point – Mass Can you name others?

Chemical Properties Observed only when substance is changed and interacts with another substance Examples: – flammability: able to burn (reacts with oxygen) – rusting: combining with oxygen to form rust – Explosive: ability to explode (reacts with oxygen) – Corrosive: ability to corrode or wear down other substances can you think of others?

Physical and Chemical Properties Review What is an example of a physical property of a candle? What is an example of a chemical property of a candle?

During a “physical change” a substance changes some physical property… During a “physical change” a substance changes some physical property… H2OH2O

…but it is still the same material with the same chemical composition. H2OH2O gas solid liquid

Physical and Chemical Properties Examples of Physical Properties Boiling point Color SlipperinessElectrical conductivity Melting point TasteOdorDissolves in water Shininess (luster) SoftnessDuctilityViscosity (resistance to flow) Volatility HardnessMalleabilityDensity (mass / volume ratio) Examples of Chemical Properties Burns in air Reacts with certain acidsDecomposes when heated Explodes Reacts with certain metalsReacts with certain nonmetals Tarnishes Reacts with waterIs toxic Ralph A. Burns, Fundamentals of Chemistry 1999, page 23 Chemical properties can ONLY be observed during a chemical reaction!

Changes in Matter There are two kinds of changes in matter: – Physical changes – Chemical changes Energy is used anytime a change in matter occurs, whether it is physical or chemical.

Physical Changes Alters form or appearance of material, but does not change material into brand new substance Examples: – chopping wood – bending wire – molding clay phase changes are physical changes – Melting – Freezing – Boiling – Condensing

Chemical Changes A chemical reaction that produces new substances’ It rearranges the atoms Examples: – wood burning – sour milk

5 signs of a Chemical Reaction 1.Color Change 2.Energy Change 3.Precipitate Formed 4.Gas Production 5.Property Change

Energy ENERGY IS USED ANYTIME A CHANGE IN MATTER OCCURS Energy has many forms: – Thermal – motion – electromagnetic – electrical – chemical

Chemical Change: Any change involving a rearrangement of atoms.

Chemical Reaction: The process of a chemical change...

During a “chemical reaction” new materials are formed by a change in the way atoms are bonded together. During a “chemical reaction” new materials are formed by a change in the way atoms are bonded together.

The formation of a mixture The formation of a compound Chemical Change Physical Change

Physical & Chemical Changes Limestone, CaCO 3 crushing PHYSICAL CHANGE Crushed limestone, CaCO 3 heating CHEMICAL CHANGEPyrex CO 2 CaO Lime and carbon dioxide, CaO + CO 2

Pyrex O2O2 H2OH2OPyrex H2O2H2O2 Light hastens the decomposition of hydrogen peroxide, H 2 O 2. The dark bottle in which hydrogen peroxide is usually stored keeps out the light, thus protecting the H 2 O 2 from decomposition. Sunlight energy