Describe the transition elements as metals that: (a) have high densities (b) have high melting points (c) have variable oxidation numbers (d) form coloured compounds (e) often act as catalysts as elements and in compounds

Identify redox reactions by changes in oxidation number using: (a) the oxidation number of elements in their uncombined state is zero (b) the oxidation number of a monatomic ion is the same as the charge on the ion (c) the sum of the oxidation numbers in a compound is zero (d) the sum of the oxidation numbers in an ion is equal to the charge on the ion