chapter 5 key terms analysisatoms elementsymbols diatomic moleculemolecular formula pure...
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Chapter 5 Key Terms
AnalysisAtoms
ElementSymbols
Diatomic Molecule Molecular Formula
Pure SubstancesMixtures
Homogeneous Mixture Solution
Heterogeneous Mixture Colloids
Tyndall EffectSuspension
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Chapter 5CLASSIFICATION OF MATTER
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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
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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
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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
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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
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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
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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
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Compound or Element
Silver Oxygen Hydrogen peroxide Iron Sugar Gold Sulfuric acid Sulfur
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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
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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
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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
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Suspensions
Particles of a mixture will eventually settle out Ex. Mud in water, snowglobes
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