O-Level Chemistry: Mastering the Periodic Table in 7 Days

The Periodic Table underpins almost every topic in O-Level Chemistry — from atomic structure and bonding to reactivity series and electrochemistry. Students who truly understand the Periodic Table can answer questions across multiple topics with confidence. Here is our 7-day plan to master it.

Day 1: Understand the Structure of the Periodic Table

Learn the organisation: periods (horizontal rows) and groups (vertical columns). Elements in the same group have the same number of valence electrons and similar chemical properties. Elements in the same period have the same number of electron shells. Understand why metals are on the left and non-metals on the right.

Day 2: Group 1 — The Alkali Metals

Li, Na, K, Rb, Cs, Fr. Going down Group 1: atomic radius increases, ionisation energy decreases, reactivity increases, melting and boiling points decrease. Know the reactions with water (produces hydrogen gas and metal hydroxide) and with oxygen (produces metal oxide).

Day 3: Group 7 — The Halogens

F, Cl, Br, I, At. Going down Group 7: atomic radius increases, electronegativity decreases, reactivity decreases, melting and boiling points increase. Know the displacement reactions: a more reactive halogen displaces a less reactive one from its salt solution.

Day 4: Transition Metals

Transition metals have variable oxidation states, form coloured compounds, and act as catalysts. Know the colours of common transition metal ions: Cu²⁺ (blue), Fe²⁺ (pale green), Fe³⁺ (yellow-brown), Mn²⁺ (pale pink), Cr³⁺ (green).

Day 5-7: Periodic Trends and Applications

Across a period (left to right): atomic radius decreases, ionisation energy increases, electronegativity increases. Use these trends to explain bonding type (ionic vs covalent), reactivity, and physical properties. Practise applying these trends to unfamiliar elements in exam questions.