Chemical Formulas and Composition StoichiometryStoichiometryDalton’s Atomic TheoryAtoms and MoleculesSlide 5CompoundsCovalent CompoundsSlide 8Compounds Containing Ionic BondsWriting Formulas and Names for Ionic Compounds (Table 2-3)Common IonsMore Polyatomic IonsSlide 13Slide 14Slide 15Atomic WeightThe MoleSlide 18Slide 19Molar MassSlide 21More ProblemsPercent CompositionSlide 24Determining Empirical Formulas from Percent CompositionSlide 26Slide 27Combustions Train – Analysis of HydrocarbonsSlide 29Slide 30Slide 31Determining Molecular FormulasSlide 33Slide 34More Fun with ConversionsSolid HydratesPurity of SamplesSolving ProblemsLet’s Do Some More ProblemsChemical Formulas and Composition StoichiometryChapter 2Stoichiometry•Describes the ___________ relationships among elements in compounds (composition stoichiometry) and among substances as they undergo chemical changes (reaction stoichiometry).Dalton’s Atomic Theory•An element is composed of extremely small, indivisible particles called _____.•All atoms of a given element have ______ properties that are ______.•Atoms cannot be _____, ______, or ______ into atoms of another element. •______ are formed when atoms of different elements combine with one another in small whole-number ratios.•The relative _____ and ____ of atoms are constant in a given compound.Atoms and Molecules•We know what atoms are and the fundamental particles that compose them.•_______ is the smallest particle of an element or compound that can have a stable, ______ existence.–This means that if a molecule contains only one type of atom it is also an element.Atoms and Molecules•Monatomic – contains only ___ atom–Na and He For these elements, an atom and a molecule are the same.•Diatomic – molecules that contain only __ atoms–H2, O2, and all halogens •Polyatomic – molecules than contain ______ atoms–P4, S8, and C60Allotropes – different _____ (geometry or number of atoms) of the same elementCompounds•Compounds are substances that contain two or more elements in fixed proportions–Compounds containing only covalent bonds•The atoms in a compound _________ electrons.•These compounds are also called molecules since they exist as individual particles.–Compounds containing ionic bonds•These compounds are held together by electrostatic interactions.•These are not molecules since they do not exist as individual particles.Covalent Compounds•The chemical formula represents the ____ present and the ______ in which the atoms of the elements occur. –Table 2.2 Show a few models to illustrate that all atoms are held together by covalent bonds.•H2O and C4H10 (models)•Notice that the formula is not necessarily the simplest ratio•_________ compounds are largely composed of C-C,C-H, and C-O bonds.–Ethanol and benzeneCovalent Compounds•Inorganic compounds largely do not contain _____ and/or ____ bonds.–H2O and NH3•Law of Definite Proportions – different pure samples of a compound always contain the same elements in the same proportion by mass–_______ of atoms can also affect the properties of compounds even if they have the same chemical formula.Demo: John Cullen’s demonstrationCompounds Containing Ionic Bonds•Held together by __________ between ions•They do not exist as individual units–Collection of a large number of ions–The formula represents the ______ of ions in the compound•Each positively-charged species is surrounded by negatively-charged species (and vice-versa)–DEMO: NaCl structureWriting Formulas and Names for Ionic Compounds (Table 2-3)•Positive and negative ions will combine in such a way to make the ionic compound _____.•Binary Ionic Compounds–You already know how to write the formulas.•Write the formula for calcium bromide and lithium sulfide–Naming a binary compound from the formula•Cation – name of the metal•Anion – drop the last portion of the name and add ‘ide’•Name AlBr3 and BeI2Common IonsMore Polyatomic IonsWriting Formulas and Names for Ionic Compounds (Table 2-3)•Ionic compounds containing a cation that can have multiple charges–The charge on the cation has to be specified–What is the charge on FeCl3 and FeCl2?•In most cases, the charge can be determined by the negatively-charged ion•Write the names for these compounds?–Write the formulas for copper(II) sulfide and iron(III) oxide.Writing Formulas and Names for Ionic Compounds (Table 2-3)•Ionic compounds containing polyatomic ions•The atoms in polyatomic ions are held together by _________.–Write the Lewis structure for SO32-•The polyatomic ions and the oppositely-charged ions are held together in the solid by _________Writing Formulas and Names for Ionic Compounds (Table 2-3)•Write the names for (NH4)2S and K2(SO4).–Notice that the charges are fixed and given on Table 2-3 for the polyatomic ions.•Write the formulas for magnesium nitrate and lithium carbonate.–If more than one polyatomic ion is needed parentheses are placed around itAtomic Weight•The atomic weight is based on the atomic mass unit.–One amu is _____ the mass of a carbon-12 atom•The atomic weight, which is given on the periodic table, is a _______ of all the naturally occurring isotopes of that elementThe Mole•A mole describes a ________ of objects, particles, or atoms. This is similar to other measurements that describe a particular quantity.–1 dozen = 12 items–Gross = 144 items–1 mole = _____________ (much larger)•Avogardo’s numberThe Mole•A mole is the amount of substance that contains as many entities as there are atoms in 12.0 grams of carbon-12.•One mole of H2O would contain 6.02  1023 molecules of H2O.•The mass of one mole of atoms of an element is equal to its atomic weight (periodic table) in grams.–This is called the molar mass (units ________).The Mole•Iron (Fe) •These conversion factors will be used extensively!!•Calculate the mass of a single Mg atom.•Calculate the number of atoms in 1.40  10-15 moles of Cu.•Calculate the number of moles in 85.3 grams of Al.atomsFemole1atoms1002.6andFeg847.55atomsFe1002.6andFemole1Feg847.552323Molar Mass•The ________ of a substance is the sum of the atomic weights of all the atoms in the formula. Expressed in amu.•_________ can be used if the compound is composed of molecules.•Molar mass is _________ to the formula weight of a compound. Expressed in grams–Indicates how many grams in