Chapter 17:classification of matter

Section 1Composition of MatterChapter 17:classification of matter

MATERIALS ARE MADE OF A PURE SUBSTANCE OR A MIXTURE OF SUBSTANCES.A PURE SUBSTANCE, or simply a substance, is either an element ( iron or silver) or a compound (NaCl, H2O).Substances cannot be broken down into simpler compounds and still maintain the properties of the original substances.(Ex.s helium, aluminum, water, salt) EEC CELEMENTS

All substances are built from atoms.If all the atoms in a substance are alike, that substance is an element.(Ex.s--graphite in pencilall carbon atoms; copper coating in penniesall copper atoms; gold barall gold)

COMPOUNDS2 or more elements can combine to form substances called compounds.A compound is a substance in which the atoms of 2 or more elements are combined. (Ex. Water=H2O2 atoms of hydrogen, 1 atom of oxygen.

MIXTURESA mixture that can be distinguished easily is called a heterogeneous mixture.Heterogeneous mixturesare mixtures made of 2 or more substances that can be easily separated by physical means. (Ex. Bowl of mixed nuts)

HETEROGENEOUS MIXTUREYou might be wearing another heterogeneous mixturepermanent-press fabrics contain fibers of 2 materials (POLYESTER AND COTTON)

MOST OF THE SUBSTANCES YOU COME INTO CONTACT WITH EVERY DAY ARE HETEROGENEOUS MIXTURES.Some are easy to see, like the ingredients in a PIZZA, but others are not.In fact, the component you see can be a mixture itself.(Ex. CHEESE--contains milk, proteins, butter fat, colorings, and other food additives.)

HOMOGENEOUS MIXTURESA homogeneous mixture contains 2 or more gaseous, liquid, or solid substances blended evenly throughout. Ex. Soft drink: water, sugar, flavoring, coloring, and carbon dioxide gascan/flatNOT OPENAnother name for a homogenous mixture is called a solution. A solutions particles are so small that they cannot be seen with a microscope and will NEVER settle to the bottom of their container.COLLOIDA colloid is a type of mixture that never settles.

Its particles are larger than those in solutions, but NOT heavy enough to settle.(Ex. Milk, fog, smoke)FOREST--FOG

COLLOIDSHEAD LIGHTS--FOGDETECTING COLLOIDSYou can tell for certain if a liquid is a colloid by passing a beam of light through it.A light beam is INVISIBLE as it passes through a solution, BUT can be SEEN as it passes through a colloid.The particles in a colloid are LARGE enough to SCATTER light, but those in a solution are NOT.The SCATTERING OF LIGHT by colloidal particles is called the Tyndall effect.

SUSPENSIONSSome mixtures of neither solutions nor colloids. (Ex. MUDDY pond water, apple CIDER (NOT juice)POND WATER is a suspension, which is a heterogeneous mixture containing a liquid in which visible particles SETTLE.Other examples--orange juice with pulp, liquid medicines

HOMOGENEOUS OR HETEROGENEOUS MIXTURE?

CHAPTER 17:CLASSIFICATION OF MATTERSection 2- Properties of MatterPHYSICAL PROPERTIESAny characteristics of a material that you can observe without changing the identity of the substances that make up the material is a physical property.Examples--APPEARANCE: color, shape, size, melting point, boiling point; BEHAVIOR: attraction to a magnet, ability to flow

SIZEROCKS/SAND

PHYSICAL PROPERTIESThe best way to separate substances depends on their physical properties.MAGNETISMIRON/SANDPHYSICAL CHANGEA change in SIZE, SHAPE, OR STATE OF MATTER is called a physical change.

These changes might involve energy changes, but the kind of substancethe IDENTITY of the element or compoundDOES NOT CHANGE.DISTILLATIONDistillation is a process for separating substances in a mixture by EVAPORATING liquid and RECONDENSING its vapor. Ex. Purifying water (distilled water)

CHEMICAL PROPERTIESA chemical property is a characteristic of a substance that indicates whether it can change into another substance.

Ex. Flammability, or the tendency of a substance to burn, because burning produces NEW SUBSTANCES.

DETECTING CHEMICAL CHANGEA change of one substance to another is a chemical change.Ex.sRUST on car fenders, SMELL of rotten eggs, food BURNING in the oven, FOAMING of an antacid tablet in waterIn some chemical changes, a RAPID RELEASE OF ENERGY---detected as HEAT, LIGHT, AND SOUNDare CLUES that changes are occurring.

WEATHERINGCHEMICAL OR PHYSICAL CHANGE?PHYSICAL CHANGELarge rocks can split when water seeps into small cracks , freezes, and expands.However, the smaller pieces of newly exposed rock still have the SAME PROPERTIES as the original rock.

CHEMICAL CHANGESolid calcium carbonate, a compound found in limestone, does not dissolve easily in water. However, when the water is slightly acidic, a new compound is formed.Slightly acidic water (CO2 and H2O) and calcium carbonate calcium hydrogen carbonate (NEW SUBSTANCE)Ex.sCaves

Burning log + oxygen = ashes + smoke + gases that escaped from log

The MASS of all substances BEFORE a chemical change EQUALS the MASS of all the substances that remain AFTER the change.CONSERVATION OF MASSMatter is neither created nor destroyed during a chemical change.LAW OF CONSERVATION OF MASS