CHEM 161 Exam 1 Review page 1 of 3 CHEM 161: Exam 1 Study Guide Chapter 1 • Scientific method • Know macroscopic, microscopic, atomic/molecular level • Significant Figures (Sig Figs) • In measurements (uncertainty) • Rounding • Exact versus approximate • In addition, subtraction • In multiplication, division • Scientific notation • Problem solving using dimensional analysis ‐ Solve problems with unit factors, showing all work! • Metric system ‐ Know all metric prefixes on p. 8 of Ch. 1 Independent Review notes ‐ Be able to perform metric‐metric conversions ‐ 1 cm31 mL and 1 dm31 L • Length, mass, weight, volume • Volume by displacement • massdensity=volume ‐ Be able to determine density, mass, or volume given the other two quantities • Temperature ‐ Be able to perform conversions for ˚F‐to‐˚C or ˚C‐to‐˚F and K‐to‐˚C or ˚C‐to‐K • Accuracy: indicates how close a measurement is to the true value • Precision: indicates how closely two measurements agree with one another • Determine and explain whether a set of data is accurate and/or precise. • Percentage: ratio of parts per 100 parts - Calculate the percentage or use a given percentage to calculate part or whole • Classification of matter: Classify substances as elements, compounds, and mixtures • Physical states of matter ‐ Determine physical state of substances (solids, liquids, gases) given descriptions of volume, shape, compressibility, attraction between particles, etc. ‐ Know terms for transition from one physical state to another (e.g. freezing, condensing, vaporizing, sublimation, deposition, etc.) • Given examples or molecular‐level images, identify elements, compounds, and mixtures, as well as solids, liquids, and gases. • Classify properties and changes as physical or chemical. Chapter 2 • KNOW people and discoveries associated with: – John Dalton’s Model – Rutherford’s Alpha Scattering Experiment – Discovery of protons, neutrons, electrons • Know law of definite proportions (or constant composition) & law of multiple proportions. • Know law of conservation of mass and solve corresponding problems. CHEM 161 Exam 1 Review page 2 of 3 Chapter 2 (Continued) • Subatomic particles • proton (p+): +1 charge, inside nucleus, ~1 amu • neutron (n): neutral, inside nucleus, ~1 amu • electron (e–): –1 charge, outside nucleus, 0 amu • Recognize the term isotope • Atomic Notation (or Nuclear Symbol): atomic number = Zmass number = AE = element symboll ‐ Be able to give atomic notation for any element given element name and mass #. • Determine the # of protons, neutrons, and electrons given mass number or atomic notation • Mass number, atomic number, element symbol - Given 2, be able to determine the missing info - • Average Atomic Mass Calculations ‐ Calculate the average atomic mass given percent natural abundance information and atomic masses of the naturally occurring isotopes of an element. (Review Chapter 2 Review Notes.) • Periodic Table: ‐ Know terms: groups, periods, Main‐group (Representative) elements, transition metals ‐ Group IA: alkali metals ‐ Group IIA: alkaline earth metals ‐ Group VIIA: halogens ‐ Group VIIIA: noble gases • Metals, nonmetals, and semimetals: ‐ Location on Periodic Table and properties • Know which elements are solids, liquids, gases at room temperature (25˚C) • Know which elements exist as diatomic molecules at 25˚C (H2, N2, O2, F2, Cl2, Br2, I2) • molecule: compound of 2 or more nonmetals ‐ formula indicates number of each atom present • ionic compound: consists of metal+nonmetal(s) - formula unit indicates ratio of ions present - recognize these have high melting points • Know ions formed by Main‐Group elements - Metals lose electrons  cations - Nonmetals gain electrons  anions • Know the names and symbols of the first 18 elements of the Periodic Table, all elements included on Fig. 2.17 on p. 56, and uranium (U). Correct spelling of element names counts! • KNOW all of names and symbols for the POLYATOMIC IONS (p. 8, Ch. 2 lecture notes) Nomenclature: – Identify a compound as ionic or molecular – Given formula of a compound, determine name. – Given name of a compound, determine formula. Ionic Compounds: metal + nonmetal(s) – cation(s) and anion(s) with overall charge of zero – Be able to determine the charges on monatomic ions using the Periodic Table – Use charges on anions to determine charges on metals that can multiple charges. Molecular Compounds: all nonmetals – Use Greek prefixes when more than one – Know ammonia, methane, hydrogen peroxide Acids: Have H in front, physical state is (aq) – Be able to name acids given the formula or determine the formula given the name. CHEM 161 Exam 1 Review page 3 of 3 Chapter 3: Atomic Mass – Know that amu is based on C‐12 isotope – Know that atomic masses reported on the periodic table are the weighted average of that element’s naturally occurring isotopes Molar Masses – Calculate molar mass of element/compound 1 mole = Avogadro's # = 6.0221023 units Mole Conversions – Convert among masses, molar mass, moles, molecules, atoms Percent Composition (or Mass Percentages) – Calculate the percent by mass of each element in a compound – Given the formula of the compound – Given combustion data for a hydrocarbon or hydrocarbon derivative Empirical and Molecular Formulas – Determine given masses of elements present – Determine using law of conservation of mass – Determine given mass percentage information – Determine the molecular formula given the empirical formula and molecular weight Balancing Equations Change coefficients, NEVER subscripts to get the same # on both sides in the following order: 1. Balance metals. 2. Balance polyatomic ions – Keep as one unit. 3. Balance hydrogens. 4. Balance carbons. 5. Balance oxygens. 6. Balance all other atoms. Interpreting Chemical Equations – reactants and products, (s), (l), (g), and (aq) – Coefficients give mole ratios Stoichiometry: Calculations involving amounts of reactants and products in a chemical reaction – coefficients in balanced equation give mole ratios – Mole‐mole relationships – Mass‐mass