Chapter 4.1 Chapter 4.1 Compounds & Compounds &

MoleculesMoleculesPages 108 - 114Pages 108 - 114

Goal 1Goal 1

Distinguish between Distinguish between compounds and mixturescompounds and mixtures

CompoundCompound

Pure substance = Pure substance = own propertiesown properties

ChemicallyChemically bonded bonded elementselements

Chemical formula = Chemical formula = constant ratiosconstant ratios

MixturesMixtures Mix of >1 pure substanceMix of >1 pure substance Properties of each remainProperties of each remain Ratios of each varyRatios of each vary

Goal 2Goal 2

Recall how to read a Recall how to read a chemical formulachemical formula

Capital letter = elementCapital letter = element

SUBscript = number of atomsSUBscript = number of atoms

Front number = number of Front number = number of molecules / molesmolecules / moles

How many molecules? ___ How many molecules? ___ How many H atoms? ___How many H atoms? ___ How many O atoms? ___How many O atoms? ___

HH22OO

How many molecules? ___How many molecules? ___ How many H atoms total? ___How many H atoms total? ___ How many O atoms total? ___How many O atoms total? ___

5 H5 H22OO

How many molecules? ___How many molecules? ___ How many C atoms? ___How many C atoms? ___ How many H atoms? ___How many H atoms? ___ How many O atoms? ___How many O atoms? ___

CC66HH1212OO66

How many molecules? ___ How many molecules? ___ How many C atoms total? ___How many C atoms total? ___ How many H atoms total? ___How many H atoms total? ___ How many O atoms total? ___How many O atoms total? ___

3 C3 C66HH1212OO66

Goal 3Goal 3

Understand chemical Understand chemical structure modelsstructure models

Ball and stick modelBall and stick model Can be 3-D or 2-DCan be 3-D or 2-D Balls = atomsBalls = atoms Sticks = bondsSticks = bonds Bond lengthBond length Bond angleBond angle May not show relative atom sizeMay not show relative atom size

Structural formulaStructural formula 2-D (usually)2-D (usually) Short-hand of ball and stickShort-hand of ball and stick Only chemical symbols Only chemical symbols Bond length not shownBond length not shown Bond angles approximateBond angles approximate

Space filling modelSpace filling model 3-D3-D Sphere = atom and electron shellSphere = atom and electron shell Bond length and angles difficult to seeBond length and angles difficult to see

Goal 4Goal 4

Understand the effects Understand the effects chemical structure has chemical structure has

on properties of on properties of compoundscompounds

Network structureNetwork structure Elements bound continuously (net)Elements bound continuously (net) STRONG solidSTRONG solid High melting and boiling pointsHigh melting and boiling points

Silicon dioxide (quartz)Silicon dioxide (quartz)

Bonded ionsBonded ions Network of + and – charges (magnets)Network of + and – charges (magnets) STRONG solidSTRONG solid High melting and boiling pointsHigh melting and boiling points

Sodium chloride (salt)Sodium chloride (salt)

Molecular compoundsMolecular compounds Molecules attracted to each otherMolecules attracted to each other WEAKEST bondWEAKEST bond

Solid = most attractive forcesSolid = most attractive forces Liquid = attractive forcesLiquid = attractive forces Gas = least attractive forcesGas = least attractive forces