What are main group elements, noble gases, transition elements and inner transition elements? State where each is placed in the modern periodic table.

1. 1 · Main group. Groups 1, 2 and 13 to 17; their outermost shell is incomplete.
2. 2 · Noble gases. Group 18; outer shell full (8, or 2 for helium); valency 0; almost unreactive gases.
3. 3 · Transition elements. Groups 3 to 12; two outermost shells incomplete; metals with variable valency, often catalysts.
4. 4 · Inner transition elements. Lanthanoids (58 to 71) and actinoids (90 to 103), in group 3 of periods 6 and 7, printed below the table.
5. 5 · Sketch. An outline of the table with blocks labelled groups 1 and 2, 3 to 12, 13 to 17 and 18, and two rows below.
6. 6 · Real life. Iron and nickel, both transition metals, are catalysts for making fertiliser and vanaspati.
7. 7 · Close. So each type of element has a fixed block in the long form table.

Scoring tip: Give the group numbers for every type; that is what most of the marks are for.