Structure of the atom: NECO Chemistry Past Questions and Answers

What the WAEC syllabus covers in Structure of the atom

Our summary: What atoms are made of, how the atomic models developed, and how electrons are arranged in shells and orbitals.

• Gross features of the atom ((1) Short account of Dalton's atomic theory and limitations, J.J. Thomson's experiment and Bohr's model of the atom. (2) Outline description of the Rutherford's alpha scattering experiment to establish the structure of the atom.)
• Atomic number/proton number, number of neutrons, isotopes, atomic mass, mass number (Meaning and representation in symbols of atoms and sub-atomic particles.)
• Relative atomic mass (Ar) and relative molecular mass (Mr) based on Carbon-12 scale ((1) Atomic mass as the weighted average mass of isotopes. Calculation of relative mass of chlorine should be used as an example. (2) Carbon-12 scale as a unit of measurement. Definition of atomic mass unit.)
• Characteristics and nature of matter (Atoms, molecules and ions. Definition of particles and treatment of particles as building blocks of matter.)
• Particulate nature of matter: physical and chemical changes (Explain physical and chemical changes with examples. Physical change - melting of solids, magnetization of iron, dissolution of salt etc. Chemical change - burning of wood, rusting of iron, decay of leaves etc.)
• Electron configuration (Detailed electron configurations (s, p, d) for atoms of the first thirty elements.)
• Orbitals (Origin of s, p and d orbitals as sub-energy levels; shapes of s and p orbitals only.)
• Rules and principles for filling in electrons ((1) Aufbau Principle, Hund's Rule of Maximum Multiplicity and Pauli Exclusion Principle. (2) Abbreviated and detailed electron configuration in terms of s, p, and d.)

Syllabus content © The West African Examinations Council (WASSCE (harmonised West African syllabus)). NECO questions are matched to the WAEC syllabus topic.