Assumed Knowledge
*Know the first 36 and common elements
CONVENTION FOR REPRESENTING DATA * Physical quantity by the unit in parentheses:
Mass (g), Pressure (Pa), ∆H (kJ mol-1), k (10-5 L mol-1 s-1) * Divide the physical quantity by the unit (better)
Mass/g, pressure/Pa, ∆H/kJ mol-1, k/10-5 L mol-1s-1 or 105k/ L mol-1 s-1 * Volume: m3, dm3(L) and cm3(mL) * Temperature: 0oC = 273.15K * Pressure: Pascal (1Pa = 1 N m-2) which is very small pressure, kPa (103Pa), MPa (106Pa)
* One PASCAL is equivalent to one NEWTON (1N) of force applied over an area of one meter squared * Bar (1 bar = 105Pa)- thermochemical data * Atmosphere (1 atm= 1.013 x 105Pa)-pressure from normal boiling temperature for a liquid and normal melting point of a solid * mmHg or Torr- both equal 133.3Pa or 1 atm/760
* mole: mol-1 mean per mole of reactant or products in the stoichiometric mixture
NAMES, FORMULAE AND CHARGES OF SOME COMMON IONS v v
DIATOMIC CATION
DIATOMIC CATION
DIATOMIC CATION
DIATOMIC CATION
CuSO4.5H2O IS COPPER (II) SULFATE PENTAHYDRATE
Hg2Cl2 IS MERCURY (I) CHLORIDE
CuSO4.5H2O IS COPPER (II) SULFATE PENTAHYDRATE
Hg2Cl2 IS MERCURY (I) CHLORIDE
v v SIGNIFICANT FIGURES
Significant figures are important as it impacts the accuracy of the results and also provides the results/data more clearly.
Calculations: * Check the number of significant figures given in the question * ADDING/SUBTRACTING VALUES: answer must have the same significant figures as the value in the information with the fewest decimal places. E.g. finding concentration * MULTIPLYING/DIVIDING VALUES: same significant figures as above with fewest significant figures. * LOGARITHIM: LOGARITHIM: the number of decimal places in the answer needs to match the number of significant figures in the value we applied
EXAMPLES
NAMING CHEMICAL COMPOUNDS
Common oxidation states of the elements in main groups of the periodic table:
Common binary compounds containing hydrogen
Polyatomic ions: are group of atoms which have acquired a positive or negative charge and behave as a single unit. Most common polyatomic cation is the ammonium ion, NH+4.
Oxidation states with molecules: Oxyanions: Oxygen forms polyatomic anions with all other non-metals (expect fluorine) and with some metals. The formulae and names of the common oxyanions and the anion of the elements in Group 14-16. * Maximum number of oxygen atoms surrounds an element in groups 13, 14, 15 or 16, the oxyanion has the ending –ate added usually to the stem of the name of the element. * One oxygen less is bonded to the central atom, the ending is –ite (except for BO-2 which is a metaborate).
* Oxyanions containing the halogens (except fluorine) The ending –ate added to the stem name is given to the anion containing 3 oxygen atoms and –ite to that containing 2. * The prefix per– (a contraction of hyper, meaning over or higher) is given to that containing 4 oxygen atoms and the prefix hypo– (meaning under or lower) to that containing one oxygen atom.
* Neutral hydrogen compound of these oxyanion dissolves in water to form an acidic solution, the –ite ending of the anion is changed to –ous and the –ate ending becomes –ic, and the word acid is added.
* In all oxyanions, the oxidation state of oxygen is –2. * The oxidation state of manganese in MnO-4 is therefore +7 in order for MnO-4 to be –1
(i.e. Mn (+7), 4(O) = 4 x 2 = –8, overall +7 – 8 = –1). * In ClO-4 the oxidation state of chlorine is +7 and the anion is called ‘perchlorate’; in MnO–4 the oxidation state of the central atom is +7 and the anion is called ‘permanganate’.
* Polyprotic acid: type of anions formed when one/two protons (not all the available protons) react with bases.
* Water of crystallisation may be indicated by hydrate or by numbers to indicate the relative numbers of each formula: e.g. Na2SO4.10H2O is sodium sulfate decahydrate or sodium sulfate– ten–water.
