Explain the main features of the modern (long form) periodic table.

1. 1 · State the law. The physical and chemical properties of elements are periodic functions of their atomic numbers.
2. 2 · Groups. 18 vertical columns. Elements in a group have the same number of valence electrons and similar properties: alkali metals, halogens, noble gases.
3. 3 · Periods. 7 horizontal rows with 2, 8, 8, 18, 18, 32 and 32 elements. The period number equals the number of shells.
4. 4 · Blocks. s-block (groups 1, 2), p-block (13 to 18), d-block (3 to 12) and f-block (lanthanides 57 to 71 and actinides 89 to 103 at the bottom).
5. 5 · Draw an outline of the table. [Outline: s-block on the left, d-block in the middle, p-block on the right, two f-block rows below; label periods 1 to 7 and groups 1 to 18]
6. 6 · Metals, non-metals and metalloids. Metals on the left and middle, non-metals on the upper right, metalloids along the zigzag line.
7. 7 · Real-life link. Sodium and potassium (group 1) and calcium and magnesium (group 2) are minerals we get from salt, coconut water, ragi and milk.
8. 8 · Close in one line. Thus the table, built on atomic number, places elements with similar properties together.

Scoring tip: A neat block outline with labels earns marks quickly. Write the period counts 2, 8, 8, 18, 18, 32, 32.