Review presentation for exam one in an introductory chemistry class.

1. Chem 105 MacroExam 1
Dr. Smith Winter 2014

2. Disclaimer
• All the problems on here come from your textbook! If you need
more, I suggest working through micro-exams and practice
sheets/parallel example problems, seeing your TA, and looking in
the book for more problems to work through over specific things
your struggling with.
• I will try, but this may not cover every little thing that will be on
the exam. Be sure to go home and study on your own as well.
• Remember to review your Mastering Chemistry homework!

3. Matter
• Matter
• Anything that has mass and occupies space
• The physical material of the universe
• Three States of Matter
• Solids
• have distinct volume & distinct shape
• Liquids
• have distinct volume but no fixed shape. May not fill a container completely.
• Gases
• no distinct shape
• expand to fill their container

4. Properties
• Quantitative = Extensive
• Depend on amount of matter present
• Qualitative = Intensive
• Independent of amount present; help identify substances
• Chemical Changes & Properties
• Involve a reaction
• Physical Changes & Properties
• Can be observed without changing the identity of the substance
• Melting, freezing, evaporating, density, mass, volume, dissolving to make a
solution

5. Elements, Compounds, Mixtures
• Pure Substance
• Made up of only one substance (can be element or compound)
• Elements
• Can’t be broken down into smaller substances
• Compounds
• Can be broken down into elements
• Two or more elements chemically combined
• Mixtures
• Two or more substances physically mixed together
• Homogeneous
• Uniform throughout; solution (like Kool-aid or milk)
• Heterogeneous
• Can see individual pieces (like trail mix or Italian dressing)

6. Experiments to Review
• Cathode Ray Tube
• Discovery of Electron
• Gold Foil
• Discovered positively charged nucleus
• Oil Drop
• Discovered charge of electron

7. Periodic Table: Elements
Atomic number:
Number of protons (and
electrons in neutral atom)
*unique to every element
Atomic mass:
amu/atom or grams/mole
(that’s why 6.022*10^23 is such a cool number!)
Average of all naturally occurring isotopes and
their relative abundances
Element Symbol

8. Atoms
• Nucleus
• Protons: positively charged
• Neutrons: no charge
• Electrons
• Around nucleus in orbitals
• Negitavely charged
• Atomic Number
• Number of protons
• Ions
• Different number of electrons; charged
• cations (+) and anions (-)
• Mass Number
• Number of protons + neutrons
• Isopotes
• Same element (# protons) with different number of neutrons

9. Laws
• Uncertainty Principle
• Can know momentum or location of electron, not both at the same time
• Law of Constant Composition
• A pure substance is uniform throughout; one sugar molecule doesn’t differ
from another sugar molecule
• Law of Definite Proportions
• Atoms combine in whole number ratios
• Law of Conservation of Mass
• Matter cannot be created nor destroyed (same amount before and after
reaction)

10. Measurements
• Number and SI unit (m, kg, s, K)
• Accurate: numbers close to the actual value
• Precise: numbers close to each other
• Significant Figures:
• All non-zeros are sig. figs.
• Zeros between two non-zeros are sig. figs.
• Zeros left of first non-zero are NOT sig. figs.
• If #>or=1, all zeros right of decimal are sig. figs.
• If #<1, all zeros at end of # and between non-zeros are sig. figs.
• Trailing zeros may or may not be sig. figs. (That’s why we use scientific
notation) but if you see them on the exam, don’t count them.
• Add & Subtract, go to last common decimal place
• Multiply & Divide, use least number of total sig figs

11. Dimensional Analysis
• Can be your best friend!
• WRITE DOWN YOUR UNITS! WRITE DOWN YOUR UNITS! I promise
they can pretty much do the thinking for you, take advantage of
that.
• Start with what the problem gives you, know where you want to
end up, use conversion factors to get from point A to point B
• Conversion factors like:
• Density -> mass/volume

12. Practice Problems
• 1.52) The concentration of carbon monoxide in an urban
apartment is 48 µg/m3. What mass of carbon monoxide in grams is
present in a room measuring 11.0 ft X 11.5 ft X 20.5 ft?
• 1.55) Gold can be hammered into extremely thin sheets called
gold leaf. An architect wants to cover a 100 ft X 82 ft ceiling with
gold leaf that is five-millionths of an inch thick. The density of
gold dis 19.32 g/cm3, and gold costs $953 per troy ounce (1 troy
ounce = 31.1034768 g). How much will it cost the architect to buy
the necessary gold?

13. Periodic Trends
Families and groups: Alkali metals, Alkaline Earth Metals,
Halogens, Noble Gases; Metals, Nonmetals, Metalloids
• Can tell ion’s
oxidation number
by its location on
the periodic
table—they all
want to be like the
noble gases! (full
octet/shell)
• Isoelectronic: same
number electrons
• Electronegativity
• Size
• Ionization Energy
• Electron Affinity
• Effective Nuclear Charge
• Family Names
• Cation and Anion Size

14. Light
• Light can be thought of as particle and a wave
• E=hv=hc/λ
• c=λν
• λ=h/mv <- DeBroglie
• Wavelength and Frequency inversely proportional
• Energy proportional to frequency
• Wavelength: length of one complete wave
• Frequency: cycles/second (Hz, S-1)
• Photoelectric Effect
• Blackbody Radiation
• Electromagnetic Spectrum
• Raul’s Mother Is Visiting Uncle Xavier’s Garden (Visible 400-700 nm)

15. Bohr Model
• Electrons in circular orbits in fixed, quantized energy levels
• Photon
• Absorb a photon to go up an energy level (excited state)
• Gives off a photon to go down an energy level (ground state)
• 1/λ=R(1/n1
2-1/n2
2)
• En=-hcRh(1/n2)

16. Quantum Mechanical Model
• Electrons in orbitals
• s = spherical
• Radial nodes starting at 2s
• p = peanut
• 1 planar node and radial nodes starting at 3p
• d = dlover leaf?
• 2 planar nodes and radial nodes starting at 4d
• f = flower (don’t worry too much about this one)
• Each orbital holds two electrons
• Remember transition metals lose s orbital electrons first
• Electron Configurations
• Expanded
• Condensed using Noble Gas configuration
• Cu and Cr exceptions
• Why? Hund’s Rule

17. Practice Problem
• 6.61) For a given value of the principal quantum number, n, how
do the energies of the s, p, d, and f subshells vary for
• Hydrogen?
• A many-electron atom?

18. Quantum Numbers
• Pauli Exclusion Principle
• n=shell (1, 2, 3….)
• l=subshell (n-1 to 0) (0=s, 1=p, 2=d, 3=f…)
• ml=orientation (-l to l)
• ms=spin (-1/2 or +1/2)

19. Practice Problem
• 6.56) Which orbital goes with the following quantum numbers?
Which are not allowed?
• 2, 1, -1, 1/2
• 1, 0, 0, -1/2
• 3, -3, 2, 1/2
• 3, 2, -2, -1/2
• 2, 0, -1, 1/2
• 0, 0, 0, -1/2
• 4, 2, 1, 1/2
• 5, 3, 0, 1/2

20. Bonding
• Ionic
• Usually metal and nonmetal
• Transfer of electrons
• Make compounds in lattice structures
• Formula weight
• Covalent
• Usually two nonmetals
• Sharing of electrons
• Make molecules
• Molecular weight

21. Nomenclature
• Metal + Nonmetal = Ionic compound
• Charges designate formula, name the elements and add –ide to the end. Cation first.
• Remember transition metals can have different charges so specify with roman numerals
• Nonmetal + Nonmetal = Covalent molecule
• Use prefixes and add –ide to the end
• Polyatomic Ions
• Nick the Camel –ate a Clam for Supper in Phoenix
• Hypo-ite, ite, ate, per-ous
• Acids
• If you ―–ate‖ too much you feel ―–ic‖ky
• ―-ite‖s like Nephites and Lamanites are people like ―-ous‖
• Hypo-ous, ous, ic, per-ic  increasing O
• Hydro-ic

22. Lewis Dot Structures
• Count total valence electrons
• Least electronegative atom in the middle
• Fill octet, create multiple bonds if too many electrons
• Resonance structures: none actually what the molecule looks like,
it’s a hybrid of all of them
• Formal charges
• Bond strengths and lengths
• Single, double, triple

23. Empirical and Molecular Formulas
• Empirical
• Whole number ratios of elements in compound
• Can be found with percent compositions
• Assume 100 g, divide by smallest number of moles, and put in whole
number ratios
• Molecular
• Actual number of each element in molecule
• Need molar mass to determine
• When doing stoichiometry, most important step is mole-to-mole
ratio

24. Practice Problems
• 3.51) Determine the empirical and molecular formulas of each of
the following substances:
• Styrene, a compound used to make Styrofoam cups and insulation, contains
92.3% C and 7.7% H by mass and has a molar mass of 104 g/mol
• Caffeine, a stimulant found in coffee, contains 49.5% C, 5.15% H, 28.9% N,
and 16.5% O by mass and has a molar mass of 195 g/mol
• Monosodium glutamate (MSG), a flavor enhancer in certain foods, contains
35.51% C, 4.77% H, 37.85% O, 8,29% N, and 13.60% Na, and has a molar mass
of 169 g/mol