11CHM 160.2 – Biagioni – FA15Chapter 2 – Atoms and ElementsThese represent the overheads used in class, but the are NOT complete class notes. They are provided as a supplement to, not replacement for, class attendance.2•Preliminary atomic modeloUnderstand how early atomic models developed•Nuclei and isotopesoUnderstand basic atomic substructure, nuclear model•Atoms and ionsoUnderstand atoms and ions based on protons and electrons•Periodic TableoIntroduce PT, arrangement of elements, key groups of elements, relationship to common ions•Atomic massesoIntroduce atomic mass scale, atomic masses of elements•“Counting” atomsoAssociate element mass ↔number of atomsChapter 2 OverviewReading: Chapter 2 (all)3Chapter 2 – Key objectives•Nuclear model for the atom.Understanding of the observations and key concepts that led to development of the modern view of the atom (includes basic atomic structure, subatomic particles, and isotopes). •Ions.Understanding of how ions can be formed from atoms by electron gain or loss.•Element names and symbols.Learn names and symbols of a variety of elements.•Periodic Table.Understand how the PT was developed and how it organizes elements on the basis of recurring properties. •Atomic mass and mole concept.Understand the relationship between atomic scale atomic masses and moles. Be able to use mole concept in calculations (including calculations of numbers of atoms). 4The old days…•Aristotle’s view of matter….wikispaces.com5Development of Dalton’s Atomic Theory (2.2 – 2.3)•Developments:oGood quantitative measurementsoLaw of Conservation of Mass°Mass neither created nor destroyed in chemical reactions.– Antoine Lavoisier10.00 g mercuric oxide⇓heat9.44 g mercury+0.56 g oxygen6Development of Dalton’s Atomic Theory (2.2 – 2.3)•Developments:oConcepts of “elements” (building blocks) versus compounds (combinations) oChemical analysis: how much of each element in compound?
27•Observation of “Law of Definite Proportions” (“Constant Composition”) for pure compounds:°The composition (proportion of elements) of a pure compound will be constant (definite), no matter what the compound’s source is or how it was prepared.– Joseph Proust8Additional observation:•Pair of elements often formed more two or more distinctcompounds.oNitrogen and oxygen:°3 distinct common compoundsoCopper and chlorine:°2 distinct common compoundso….•Law of Multiple proportions (Dalton):oWhen two elements (A and B) form two different compounds, masses of B that combine with 1 g A can be expressed as a ratio of small whole numbers. (Tro)9Examples: two distinct Cu – Cl compoundsPure Cu – Cl compoundSampleSample mass (g)g Cug ClA5.323.421.90B4.221.992.23See Tro: Example andPractice 2.210•Law of Multiple Proportions:oOther examples:°CO and CO2°CuO and Cu2O°NO and NO2and N2O°FeO and Fe2O3and Fe3O4oKey: