atoms, molecules and water essential building blocks for living organisms
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Atoms, Molecules Atoms, Molecules and Water and Water
Essential Building Blocks Essential Building Blocks for Living Organismsfor Living Organisms
Comparison of Terms Comparison of Terms
ElementElement Substance that cannot be broken Substance that cannot be broken down to another substance with down to another substance with different propertiesdifferent properties
AtomAtom Smallest unit that has characteristic Smallest unit that has characteristic properties of the elementproperties of the element
MoleculeMolecule Two or more atoms joined by Two or more atoms joined by chemical bondschemical bonds
Composition Composition of an Atom of an Atom
• NucleusNucleus Proton = positively charged particle (+)Proton = positively charged particle (+) Neutron = uncharged particle (n or Neutron = uncharged particle (n or ++))Number of protons + Number of neutrons = Atomic massNumber of protons + Number of neutrons = Atomic massNumber of protons = Atomic numberNumber of protons = Atomic number • Electrons = negatively charged particlesElectrons = negatively charged particles
Number of electrons = Number of protons Number of electrons = Number of protons
Each electron circles the nucleus in an orbitEach electron circles the nucleus in an orbitrepresenting a specific energy level. representing a specific energy level.
CC121266
4Chapter 2ƒ2-1
Atomic ModelsAtomic Models
Hydrogen (H)Hydrogen (H) Helium (He)Helium (He)NucleusNucleus
ElectronElectronShellShell
5Chapter 2ƒ2-2
Different Kinds of AtomsDifferent Kinds of Atoms
HeliumHelium
Max 2eMax 2e--Max 2eMax 2e--
CarbonCarbon
+7p+7p++
+4p+4p++
+2p+2p++
InnermostInnermostelectron shellelectron shell
+4e+4e--
+4n+4n±±
+2n+2n±±
+2e+2e--
OxygenOxygenMax 8eMax 8e--Max 8eMax 8e--
+7e+7e--
+8n+8n±±
PhosphorusPhosphorus
+5p+5p++
+5e+5e--
+4n+4n±±
CalciumCalcium
22ee--
22nn 22pp++6e6e--
66nn 6p 6p++
8e8e--
88nn 8p 8p++15e15e--
1616nn 15p 15p++20e20e--
2020nn 20p 20p++
Applying Your Knowledge Applying Your Knowledge
MagnesiumMagnesium ChlorineChlorine
Atomic NumberAtomic Number 1212 1717
Atomic MassAtomic Mass 2424 3535
Number of ProtonsNumber of Protons
Number of NeutronsNumber of Neutrons
Number of ElectronsNumber of Electrons
Electron Energy LevelsElectron Energy Levels
Energy Energy LevelLevel
Capacity for Capacity for ElectronsElectrons
11 22
22 88
33 88
In forming molecules, atoms combine In forming molecules, atoms combine to fill their outer energy levels.to fill their outer energy levels.
Applying Your Knowledge Applying Your Knowledge
MagnesiumMagnesium ChlorineChlorine
Total Number of Total Number of Electrons Electrons
1212 1717
Number of Electrons Number of Electrons in First Electron Shellin First Electron Shell
Number Electrons in Number Electrons in Second Electron ShellSecond Electron Shell
Number of ElectronsNumber of Electrons
In Third Electron ShellIn Third Electron Shell
Chemical BondsChemical BondsForces holding atoms togetherForces holding atoms together
BondBond CharacteristicsCharacteristics
IonicIonic One atom loses an electron, One atom loses an electron, another gains an electronanother gains an electron
CovalentCovalent Atoms share electronsAtoms share electrons
Polar Polar CovalentCovalent
Atoms share electrons Atoms share electrons unequallyunequally
HydrogenHydrogen Covalently-bound hydrogen is Covalently-bound hydrogen is attracted to another atomattracted to another atom
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Ionic Bonding in NaClIonic Bonding in NaCl
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±±++±±++±±++ ±±++±±++±±
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SodiumSodium#e=2+8+1=#p#e=2+8+1=#p
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±±++±±++±±++ ±±++±±++±±
++±±++
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ChlorineChlorine#e=2+8+7=#p#e=2+8+7=#p
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Sodium ion Sodium ion #e=#p-1#e=#p-1
ChlorineChlorineion #e=#p+1ion #e=#p+1
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ElectronElectronCompletelyCompletelyTransferredTransferred
NegativeNegativechargecharge
PositivePositivechargecharge
Ionic Bonding in NaClIonic Bonding in NaCl
ClCl-- ClCl-- ClCl-- ClCl--
ClCl-- ClCl-- ClCl-- ClCl--
ClCl-- ClCl-- ClCl-- ClCl--
ClCl-- ClCl-- ClCl-- ClCl--
NaNa++ NaNa++ NaNa++
NaNa++ NaNa++ NaNa++
NaNa++ NaNa++ NaNa++
NaNa++
NaNa++
NaNa++
NaNa++ NaNa++ NaNa++ NaNa++
• Opposites Opposites attract.attract.
• Sodiums nestle Sodiums nestle between between chlorines.chlorines.
• Perfectly Perfectly cubical crystals cubical crystals form.form.
ClCl-- ClCl-- ClCl-- ClCl--
ClCl-- ClCl-- ClCl-- ClCl--
ClCl-- ClCl-- ClCl-- ClCl--
ClCl-- ClCl-- ClCl-- ClCl--
NaNa++ NaNa++ NaNa++
NaNa++ NaNa++ NaNa++
NaNa++ NaNa++ NaNa++
NaNa++
NaNa++
NaNa++
NaNa++ NaNa++ NaNa++ NaNa++
In Water, Polar Covalent Bonds In Water, Polar Covalent Bonds Join Oxygen and Hydrogen Join Oxygen and Hydrogen
Hydrogen Bonds Join Water MoleculesHydrogen Bonds Join Water Molecules
OO
OO
HH
HH
HHHH+
+
+
–
–
+
+
HydrogenHydrogenBondsBonds
Water molecules Water molecules carry slight carry slight chargescharges
Electrons favor Electrons favor O over HO over H
Hydrogen bonds Hydrogen bonds form between O form between O of one water of one water molecule and H molecule and H of another of another
Due to hydrogen Due to hydrogen bonding, water showsbonding, water shows
Surface tension: concentration of Surface tension: concentration of hydrogen bonds at hydrogen bonds at air-water interface air-water interface
•Cohesion: water molecules associate Cohesion: water molecules associate with each otherwith each other
Due to hydrogen Due to hydrogen bonding, water showsbonding, water shows
Capillary Action: movement of water Capillary Action: movement of water through a tube by through a tube by cohesion and adhesion cohesion and adhesion
Adhesion: water molecules associate Adhesion: water molecules associate with other molecules or surfaceswith other molecules or surfaces
Due to hydrogen Due to hydrogen bonding, water showsbonding, water shows
Imbibition: movement of water into wood Imbibition: movement of water into wood or gelatin by capillary action or gelatin by capillary action
Due to hydrogen bonding, Due to hydrogen bonding, water resists temperature changewater resists temperature change
Water has high values forWater has high values for
Specific Heat: heat needed Specific Heat: heat needed to change temperatureto change temperature
Heat of Vaporization: heat needed to Heat of Vaporization: heat needed to convert liquid to gas convert liquid to gas
Due to hydrogen bonding, Due to hydrogen bonding, density decreases upon freezingdensity decreases upon freezing
Ice floats!Ice floats!
Water as a SolventWater as a Solvent
• Substances that dissolve in water = Substances that dissolve in water = hydrophilichydrophilic– PolarPolar– IonicIonic
• Substances that are insoluble in Substances that are insoluble in water = hydrophobicwater = hydrophobic– Non-polar Non-polar
NaCl Dissolves in WaterNaCl Dissolves in Water
Ionic bonds Ionic bonds of NaCl give of NaCl give +/- charges +/- charges
Water has Water has partial +/- partial +/- chargescharges
O tends O tends to join to join with Nawith Na++
H tends H tends to join to join with Clwith Cl--
DissociationDissociation
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WaterWaterWaterWater
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HydroxideHydroxideionion
HydroxideHydroxideionion
++
HydrogenHydrogenionion
HydrogenHydrogenionion
A few water molecules naturally A few water molecules naturally dissociatedissociate into ions into ions
A few water molecules naturally A few water molecules naturally dissociatedissociate into ions into ions
• Hydroxide ionHydroxide ion is negative and is negative and basicbasic• Hydroxide ionHydroxide ion is negative and is negative and basicbasic
• Hydrogen ionHydrogen ion is positive and is positive and acidicacidic• Hydrogen ionHydrogen ion is positive and is positive and acidicacidic
The pH ScaleThe pH Scale
NeutralNeutralpHpH++ = pOH = pOH––
Increasingly AcidicIncreasingly AcidicpHpH++ > pOH > pOH––
Increasingly BasicIncreasingly BasicpHpH++ < pOH < pOH––
0000 1111 2222 3333 4444 5555 6666 7777 8888 9999 10101010 11111111 12121212 13131313 14141414
LemonLemonJuiceJuice
LimeLimeJuiceJuice
StomachStomachAcidAcid
BeerBeerCoffeeCoffee
UrineUrine
WaterWater
BloodBlood
SeaSeaWaterWater
BakingBakingSodaSoda
BleachBleach
AmmoniaAmmonia
OvenOvenCleanerCleaner
101000101000 1010-1-11010-1-1 1010-2-21010-2-2 1010-3-31010-3-3 1010-4-41010-4-4 1010-5-51010-5-5 1010-6-61010-6-6 1010-7-71010-7-7 1010-8-81010-8-8 1010-9-91010-9-9 1010-10-101010-10-10 1010-11-111010-11-11 1010-12-121010-12-12 1010-13-131010-13-13 1010-14-141010-14-14
1010-14-141010-14-14 1010-13-131010-13-13 1010-12-121010-12-12 1010-11-111010-11-11 1010-10-101010-10-10 1010-9-91010-9-9 1010-8-81010-8-8 1010-7-71010-7-7 1010-6-61010-6-6 1010-5-51010-5-5 1010-4-41010-4-4 1010-3-31010-3-3 1010-2-21010-2-2 1010-1-11010-1-1 101000101000
Applying Your KnowledgeApplying Your Knowledge
• What would be the chemical formula if What would be the chemical formula if magnesium and chlorine united to form magnesium and chlorine united to form a molecule? a molecule? (Mg=magnesium; Cl=chlorine) (Mg=magnesium; Cl=chlorine)
• Which electrons from each atom are Which electrons from each atom are involved in forming the bond(s)?involved in forming the bond(s)?