General Chemistry Semester Review
Skip Chapter 1
Chapter 2 – ChemQuest #1 & 2
 Metric units: meter, liter & grams
 Metric prefixes: milli, centi, kilo etc.
 Scientific notation – use the exponent button (EE or EXP) on the calculator not the ^ button!
 Dimensional analysis: cancel units! Show your set-up! See the example below.
 Significant figures: 1. Nonzero digits are always significant. 2. Any zeros between two sig figs are significant. 3.
Trailing zeros IN THE DECIMAL PORTION ONLY are also significant. 4. When multiplying or dividing sig figs keep
the fewest number of significant digits for your answer.
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so density has units of
 Ex. The density of gold is 19.3 g/ml. If you had 32 grams of gold, how many liters of space would it occupy?
Note that the answer has two significant digits.
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Accuracy – how close to the truth. Precision – how close several measurements are to eachother.
Error = your answer – the truth
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% error =
Note that the top of the fraction is the ABSOLUTE VALUE of error.
Chapter 3 – ChemThink: Particulate Nature of Matter
 Elements (one symbol from the periodic table) vs. compounds (2 or more symbols from the periodic table)
 Mixtures (this AND that. ex. salt and iron) vs. pure substances (one type of chemical only. Ex. water or oxygen.)
 Heterogeneous vs. homogeneous (only homogeneous when dissolved or melted togethe (alloy) and mixed very
well.)
 Physical properties/physical change (material stays the same: melting point, density, ice melting, glass
breaking…)
 Chemical properties/chemical change (new material forms: burns producing ash, rusts, etc.) (evidence of
chemical change may include a new gas or a new solid forming, change in temperature, new color: bananas
ripening produce a new smell and a new color, chemical heat packs produce a change in temperature, hard
water reacts with soap to form soap scum…)
Chapter 4 – ChemThink: atoms, ChemThink: isotopes and ChemThink: ions
 Early models of the atom and why each model was discarded:
o billiard ball model of the atom, discarded because we discovered electrons & positive stuff;
o plum pudding (raisin bread) discarded because Ernst Rutherford discovered the nucleus;
o nuclear model, discarded because electrons occupy energy levels (orbitals);
o orbital model, discarded because electrons are very strange;
o quantum model of the atom, not discarded yet
 Protons, neutrons & electrons (location in atom, charge, purpose, relative mass – see the ChemThink for info)
 Atomic number (number of protons), mass number (protons + neutrons)
 Number of electrons (same as protons if it’s in an atom,if it’s an ion you must adjust for the charge: if you have
a positive charge, subtract that many electrons; if you have a negative charge, add that many electrons)
 1 amu = 1.6606 x 10-24 g Use this in dimensional analysis problems. Amu is a unit used for the mass of atoms.
 Isotopes (have different numbers of neutrons but same numbers of protons:
)
 Average atomic mass is calculated knowing % abundance and the mass of each isotope of an element: 7.59% of
an element’s atoms have a mass of 6.015 amu and the rest have a mass of 7.016 amu. What is the average mass
of the element? (0.0759)(6.015 amu) + (0.9241)(7.016 amu) = 6.939 amu
Chapter 5
 Electromagnetic radiaton (in order of increasing energy: radio/TV waves, microwaves, IR, red, orange…violet,
UV, x rays, gamma rays)
 Frequency, has the symbol ν, measured in Hertz (Hz) or /s (the per-second) ex. 5.4x1014 Hz or 5.4 x 1014/s
 Wavelength, has the symbol λ, measured in meters or nanometers
 c = λ ν where c = 2.998 x 108 m/s and is the speed of all electromagnetic radiation.
 E = hν where E is energy, measured in Joules and h is Planck’s constant: 6.626 x 10-34 Js
Chapter 6
 Dimitri Mendeleev: father of the periodic table
 Groups are the columns on the periodic table. Some groups have specific names: alkali metals, halogens, noble
gases and alkaline metals.
 Metals, nonmetals and metalloids all have specific locations on the periodic table
 Elements in the same group tend to behave similarly (used to predict physical and chemical properties and
bonding: H2O exists, so Li2O, Li2S, K2O etc. must also be possible compounds.)
 KNOW THE ASSIGNED ELEMENT SYMBOLS AND SPELLINGS!
Chapter 7 – ChemThink: Ionic Formulas and Ionic Bonding
 Ions form by gaining or losing electrons when they try to get the same number of electrons as a noble gas.
 Oppositely charged ions attract & form ionic bonds
 Ionic formulas are always neutral and reduced: Mg2O2 is really MgO.
 The positive ion is always written first in an ionic formula: NaCl, not ClNa
 Naming ionic compounds: just name each ion.
o Simple negative ions (made just from one nonmetal) have ion names that end in “ide.” (phosphide,
nitride, oxide, sulfide, fluoride, chloride, bromide and iodide)
o Polyatomic ions have special names – check the list.
o Transition metals always need a Roman numeral to indicate their charge (dark grey on the periodic
table).
o Memorize the fact that silver ions always have a 1+ charge and zinc and cadmium ions are always 2+.
They are the only transition metals that do not need Roman numerals.
 Metallic bonding – metal ions surrounded by an electron sea
 Metallic vs.ionic bonding: melting point, conductivity of heat and electricity, etc. Check your notes!
 Alloys: homogeneous mixture of metals melted together
Chapter 8 – ChemThink: Covalent Bonding
 Covalent bond – atoms sharing electrons in order to be stable: Octet rule
 Lewis diagrams show all valence electrons.
o Lewis diagrams must have the right number of electrons
o All atoms in a Lewis diagram must be surrounded by 8 electrons (except hydrogen which must have 2
electrons)
o Use single, double and triple bonds in order to satisfy these two rulse
 Naming covalent compounds: use Greek prefixes: mono, di, tri, tetra, penta, hexa, hepta, octa, nona & deca
before EVERY element (except when there is only one of the first element)
 Geometry
 Electronegativity
 Polarity