Memorization

Systematic covering of memorization points for the US National Chemistry Olympiad.

Welcome to the Memorization section! Here, we list the key concepts, conversions, and other facts that are very useful for IB-level and above Chemistry. If you have any free time (e.g. on a road trip), you can pull this list out whenever you want. This list is being constantly updated.

Conversions:

1 eV = 1.602 * 10^-19 J
1 electron = 9.11 * 10^-31 J
1 A = 10^-10 m

Common oxidation states:

Sc: 3+
Ti: 2+, 3+, 4+
V: 2+, 3+, 4+, 5+
Cr: 2+, 3+, 6+
Mn: 2+, 7+
Fe: 2+, 3+
Co: 2+, 3+
Ni: 2+
Cu: 1+, 2+

Flame colors:

Lithium: Red
Sodium: Yellow
Potassium: Purple
Copper: Blue
Boron: Blue
Calcium: Red
Strontium: Red

Ion colors:

Manganate (MnO4): Purple
Chromate (CrO4): Yellow
Dichromate (Cr2O7): Orange
Iron (Fe3+): Yellow
Cobalt (Co2+): Pink (Co(H2O)6) or Blue (CoCl4)
Copper (Cu2+): Blue

Activity series:

Potassium
Sodium
Calcium
Magnesium
Aluminum
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Gold

Generally soluble:

NO3- is always soluble
C2H3O2- is always soluble
ClO4- and ClO3- are always soluble
Cl-, I- (exception: Cu+), and Br- are always soluble except PMS
- F- is NOT soluble in Ca, Mg, Pb but IS soluble in Ag+
(SO4)2- is always soluble except PMS and CaStroBaer

Generally insoluble:

(CO3)2- is always insoluble (except Group I/NH4+ cations)
(PO4)3- is always insoluble (except Group I/NH4+ cations)
OH- and O2- are always insoluble (except Group I/NH4+ cations and StroBaer)
(S)2- is always insoluble (except Group I/NH4+ cations and CaStroBaer)

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