1

Chapter 5 Key Terms

AnalysisAtoms

ElementSymbols

Diatomic Molecule Molecular Formula

Pure SubstancesMixtures

Homogeneous Mixture Solution

Heterogeneous Mixture Colloids

Tyndall EffectSuspension

2

Chapter 5CLASSIFICATION OF MATTER

3

History

Greek Philosophers proposed that all matter was composed of 4 elements: earth, fire, water, air

1661, Robert Boyle published The Sceptical Chymist Element is any substance that cannot be broken

down into simpler substances System for classifying matter

ElementsCompoundsMixtures

4

Elements

Any substance that cannot be broken down into a simpler substance by ordinary chemical means

Elements are composed of only 1 type of atom Atoms make up all elements Symbols – used to represent names of elements

Consists of one or two letters derived from the element’s name

Oxygen = OHydrogen = H

5

Elements

First letter is capitalized, second letter is lowercase Some symbols are derived from the element’s Latin

nameAuAgNaFe

MEMORIZE elements on page 92Spelling and symbol

6

Elements

Most elements are solids at room temperatureMercury and Bromine are liquidsEleven are gases

Diatomic elements (molecule)Elements that combine with itself to form 2 atom units

O2, H2

Most elements are naturally occurring, but some are only found in laboratories

7

Compounds

Substances with 2 or more different elements chemically bonded togetherWaterSugar

MoleculesGroup of atoms held together by strong attractive forcesSmallest particle in a compoundHave all the same characteristics of the compound

A single molecule of water contains 2 H’s and 1 O

8

Compounds

Molecular formulas: tell us how many atoms of each element are in a moleculeWater – H2O

Baking Soda – NaHCO3

Subscripts Coefficients

2 H2SO4

4 CaCO3

Know the chemical formulas for the compounds on page 97

9

Compound or Element

Silver Oxygen Hydrogen peroxide Iron Sugar Gold Sulfuric acid Sulfur

10

Mixtures

Consists of 2 or more pure substances (elements or compounds)Ex. Sugar water (sugar and water)

The parts of a mixture keep their own propertiesSugar and water do not bond, they just mixSeparated by physical means

Parts of mixture can be in any proportionParts are physically combined, not chemically

11

Mixtures

Described by percent compositiono 10 g of sugar and 90 g water – 10% sugar solution

Two types of mixtures Homogeneous

Mixture that appears the same throughout Ex. Air, stainless steel, 14-karat gold AKA solution

Heterogeneous Mixture has visibly different parts Ex. Granite

12

Colloids

Heterogeneous mixtures with small particles dispersed throughout which are hard to see

Apparent via Tyndall EffectPass a beam of light through solutionSee the beam in the solution = colloidNo beam = a true solutionBeam of light is dispersed by the

particles in the colloid Ex. Milk, Mayonnaise, lotions

13

Suspensions

Particles of a mixture will eventually settle out Ex. Mud in water, snowglobes