1 General Physical Science General Physical Science Chapter 12 Chapter 12 Chemical Bonding Chemical Bonding The Law of Conservation of The Law of Conservation of Mass Mass No detectable change No detectable change in the total mass in the total mass occurs during a occurs during a chemical reaction chemical reaction Example Example In a chemical reaction involving carbon In a chemical reaction involving carbon and oxygen, laboratory measurements and oxygen, laboratory measurements showed that the complete burning in showed that the complete burning in oxygen of 4.09 g of carbon produced oxygen of 4.09 g of carbon produced 15.00 g of carbon dioxide as the only 15.00 g of carbon dioxide as the only product. How many grams of oxygen product. How many grams of oxygen reacted? reacted? 15.00 g = 4.09 g + x g 15.00 g = 4.09 g + x g x = 15.00 x = 15.00 - 4.09 = 10.91 g oxygen 4.09 = 10.91 g oxygen
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General Physical ScienceGeneral Physical Science
Chapter 12Chapter 12
Chemical BondingChemical Bonding
The Law of Conservation of The Law of Conservation of
MassMass
�� No detectable change No detectable change
in the total mass in the total mass
occurs during a occurs during a
chemical reactionchemical reaction
ExampleExample
�� In a chemical reaction involving carbon In a chemical reaction involving carbon
and oxygen, laboratory measurements and oxygen, laboratory measurements
showed that the complete burning in showed that the complete burning in
oxygen of 4.09 g of carbon produced oxygen of 4.09 g of carbon produced
15.00 g of carbon dioxide as the only 15.00 g of carbon dioxide as the only
product. How many grams of oxygen product. How many grams of oxygen
reacted?reacted?
�� 15.00 g = 4.09 g + x g15.00 g = 4.09 g + x g
�� x = 15.00 x = 15.00 -- 4.09 = 10.91 g oxygen4.09 = 10.91 g oxygen
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The Law of Conservation of The Law of Conservation of
MassMass
�� Learning Goal:Learning Goal:
�� State and use the Law of Conservation of State and use the Law of Conservation of
Mass.Mass.
�� Questions: 1Questions: 1--33
�� Exercise: 1, 3Exercise: 1, 3
Law of Definite ProportionsLaw of Definite Proportions
�� Different samples of a pure compound Different samples of a pure compound always contain the same elements in the always contain the same elements in the same proportion by mass.same proportion by mass.
�� Atomic Mass (AM)Atomic Mass (AM)�� The number below the elemental symbol.The number below the elemental symbol.
�� Formula Mass (FM)Formula Mass (FM)�� Sum of the atomic massesSum of the atomic masses
�� AKA formula weight/molecular weightAKA formula weight/molecular weight
ExampleExample
�� Calculate the formula mass of PbCrOCalculate the formula mass of PbCrO44, the , the
bright yellow compound used in paint for bright yellow compound used in paint for
the yellow lines on streets.the yellow lines on streets.
�� Atomic MassesAtomic Masses
�� PbPb = 207.2; Cr = 52.0; O = 16.0= 207.2; Cr = 52.0; O = 16.0
�� 207.2 + 52.0 + (4 x 16.0)207.2 + 52.0 + (4 x 16.0)
�� 323.2323.2
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Percent by MassPercent by Mass
�� Since all compounds have the same Since all compounds have the same
elemental makeup, we should be able to elemental makeup, we should be able to
calculate how much of each element is calculate how much of each element is
present (by mass)present (by mass)
�� (Mass element / FM) * 100%(Mass element / FM) * 100%
ExampleExample
�� Calculate the percent by mass for carbon Calculate the percent by mass for carbon
and oxygen in dry ice (COand oxygen in dry ice (CO22))
�� Formula Mass = 12.0 + 16.0*2 = 44.0Formula Mass = 12.0 + 16.0*2 = 44.0
�� Formula Mass Percent CarbonFormula Mass Percent Carbon
�� Ions free to move in solutionIons free to move in solution
Stock System NomenclatureStock System Nomenclature
�� Applies to metals that form ions with more Applies to metals that form ions with more than one chargethan one charge�� Typically transition elementsTypically transition elements
�� Some heavier postSome heavier post--transition representative transition representative metals alsometals also
�� Name of metal (charge of ion) anionName of metal (charge of ion) anion�� iron(II) chlorideiron(II) chloride
�� copper(I) nitratecopper(I) nitrate
Ionic BondingIonic Bonding
�� Learning GoalsLearning Goals�� Write formulas for ionic compoundsWrite formulas for ionic compounds
�� Describe the characteristics of ionic Describe the characteristics of ionic compoundscompounds
�� Name compounds containing a metal that Name compounds containing a metal that forms more than one ion.forms more than one ion.
�� Questions: 19 Questions: 19 -- 2121
�� Exercises: 13 Exercises: 13 -- 19 odd19 odd
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Covalent BondingCovalent Bonding
�� Sharing of electronsSharing of electrons
�� Stable covalent bonds will give all atoms a Stable covalent bonds will give all atoms a noble gas configurationnoble gas configuration�� Shared electrons are counted twice!Shared electrons are counted twice!
�� HH22, Cl, Cl22, H, H22O, NHO, NH33, CH, CH44..
�� Multiple bonding between 2 atomsMultiple bonding between 2 atoms�� Double bondsDouble bonds
�� Triple BondsTriple Bonds
Covalent Bond in HydrogenCovalent Bond in Hydrogen
Polyatomic IonsPolyatomic Ions
�� Contain both ionic and covalent Contain both ionic and covalent
characteristicscharacteristics
�� Atoms in a polyatomic ion are held together Atoms in a polyatomic ion are held together
with covalent bondswith covalent bonds
�� To get enough electrons to To get enough electrons to ‘‘shareshare’’ and and
complete all octets the polyatomic anions complete all octets the polyatomic anions
need need ‘‘extraextra’’ electrons electrons -- gives negative chargegives negative charge
�� This then forms ionic bond with metals.This then forms ionic bond with metals.
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Prediction of Bond TypePrediction of Bond Type
�� Only nonmetals Only nonmetals -- covalentcovalent
�� Write molecular formulas and Lewis structures Write molecular formulas and Lewis structures
for covalent compoundsfor covalent compounds
�� Describe the characteristics of covalent Describe the characteristics of covalent
compoundscompounds
�� Questions: 22 Questions: 22 -- 3131
�� Exercises: 21 Exercises: 21 -- 29 odd29 odd
Hydrogen BondingHydrogen Bonding
�� Solubility of table saltSolubility of table salt�� ionion--dipole interactiondipole interaction
�� molecules have dipolemolecules have dipole--dipole interactiondipole interaction�� energy that holds the molecule togetherenergy that holds the molecule together
�� higher the energy, higher the boiling pointhigher the energy, higher the boiling point
�� Hydrogen bondHydrogen bond�� Special type of dipoleSpecial type of dipole--dipole interaction.dipole interaction.
�� Large value for dipoleLarge value for dipole
�� small size of hydrogensmall size of hydrogen
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Hydrogen BondingHydrogen Bonding
�� Occurs when H bonded to F, O, or NOccurs when H bonded to F, O, or N
�� Hydrogen bonding about 5Hydrogen bonding about 5--10% of 10% of
strength of covalent bondstrength of covalent bond
�� Typical molecular interaction less than 1% Typical molecular interaction less than 1%
of covalent bond!of covalent bond!
�� Causes ice to be less dense than waterCauses ice to be less dense than water
�� Leads to life on Earth!Leads to life on Earth!
�� Holds DNA togetherHolds DNA together
�� Leads to life on Earth!Leads to life on Earth!
Hydrogen BondingHydrogen Bonding
�� Learning GoalsLearning Goals
�� Predict when hydrogen bonding will occurPredict when hydrogen bonding will occur
�� Describe how hydrogen bonding affects a Describe how hydrogen bonding affects a
compoundcompound’’s properties.s properties.
�� Questions: 32, 33Questions: 32, 33
�� Key Terms; Matching, Multiple Choice, and Key Terms; Matching, Multiple Choice, and