Periodic chemistry: WAEC Chemistry Past Questions and Answers

What the WAEC syllabus covers in Periodic chemistry

Our summary: How the periodic table is organised, the trends across periods and down groups, the halogens and the first transition metals.

• Periodicity of the elements (Electron configurations leading to group and periodic classifications.)
• Different categories of elements in the periodic table (Metals, semi-metals, non-metals in the periodic table and halogens. Alkali metals, alkaline earth metals and transition metals as metals.)
• Periodic law (Explanation of the periodic law.)
• Periodic law: trends on periodic table (Periodic properties; atomic size, ionic size, ionization energy, electron affinity and electronegativity. Simple discrepancies should be accounted for in respect to beryllium, boron, oxygen and nitrogen.)
• Periodic law: periodic gradation of the elements in the third period (Na - Ar) ((1) Progression from: (i) metallic to non-metallic character of element; (ii) ionic to covalent bonding in compounds. (2) Differences and similarities in the properties between the second and the third period elements should be stated.)
• Reactions between acids and metals, their oxides and trioxocarbonates (IV) ((1) Period three metals (Na, Mg, Al). (2) Period four metals (K, Ca). (3) Chemical equations. (4) pH of solutions of the metallic oxides and trioxocarbonates.)
• Periodic gradation of elements in group seven, the halogens: F, Cl, Br and I (Recognition of group variations noting any anomalies. Treatment should include the following: (a) physical states, melting and boiling points; (b) variable oxidation states; (c) redox properties of the elements; (d) displacement reaction of one halogen by another; (e) reaction of the elements with water and alkali (balanced equations required).)
• Elements of the first transition series, ₂₁Sc – ₃₀Zn ((1) Their electron configurations, physical properties and chemical reactivity of the elements and their compounds. (2) Physical properties should include: physical states, metallic properties and magnetic properties. (3) Reactivity of the metals with air, water, acids and comparison with s-block elements (Li, Na, Be, Mg). (4) Other properties of transition metals should include: (a) variable oxidation states; (b) formation of coloured compounds; (c) complex formation; (d) catalytic abilities; (e) paramagnetism; (f) hardness.)

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