Ch3. Periodicity
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Definitions
Alkali metals: Group 1 elements.
Catalyst: A substance that increases the rate of reaction while being recoverable unchanged at the final stage of the reaction. Examples of catalytic transition metals:
Fe is used in Haber process;
V2O5 in Contact process;
Ni in hydrogenation reactions;
MnO2 in the decomposition of hydrogen peroxide
Catalyst, heterogeneous: In different state than reactants
Catalyst, homogeneous: In the same state as reactants
Colored complex: A complex is a compound in which molecules or ions form dative bonds to a metal atom or ion. Colors are due to e- transitions between different d orbitals.
Co-ordination number: Number of lone pairs bonded to the metal ion.
Cl- often gives 4 coordinate bonds, CN- gives 6, H2O gives 6 and NH3 gives 4 or 6.
Electronegativity: Relative measure of the ability an atom has to attract a shared pair of electrons.
Group: Elements with the same number of valence e-.
Halide ions: Ions of the halogens.
Their presence can be detected by the addition of silver nitrate. AgCl is white, AgBr is cream-colored, and AgI is yellow. Silver halides react with light to form silver metal.
Ligand: A molecule or ion that can donate an electron pair.
Metalloid: An element that possesses some of the properties of a metal and some of a non-metal. While metal oxides tend to be basic and non-metal oxides tend to be acidic, metalloid oxides such as aluminium oxide can be amphoteric.
Transition element: An element that possesses an incomplete d sub-level in one or more of its oxidation states.
Often very efficient catalysts as they can exist in a variety of oxidation states (all except Ti have oxidation state of +2). Form coloured complexes.
•Basic concepts and shielding effect [.pdf]
•Periodic table properties [.pdf]
•How to explain chemical phenomena [.pdf]
• Periodic table and main types of elements [.gif]
• Periodic table and properties trends [.gif]
• Periodic table and orbitals [.gif]
• Periodicity (SL/HL) [.pdf]
Brainiac: Alkali metals + water
•Videos for each element of the periodic table
•The periodic table on the web
•The complete and interactive periodic table
•The periodic table in comics
