Lesson Notes By Weeks and Term v4 - JHS 2

Lesson Video

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Performance objectives

• Describe what an atom is and its structure.
• Identify the sub-atomic particles and their locations.
• State the electrical charges of these particles.
• Explain the difference between atomic number and mass number.
• Calculate the number of protons, neutrons, and electrons in an atom.

Lesson summary

All the materials we use in Ghana—water in our homes, aluminium pots, iron roofing sheets, salt, charcoal, plastics, gold, and even the air we breathe—are made up of very tiny particles. Science explains that the smallest unit of an element is an atom, and every atom is made of sub-atomic particles. Understanding atoms helps learners to explain why materials behave differently (e.g., why metals conduct electricity, why salt dissolves in water, why iron rusts, and why charcoal burns).

Lesson notes

2.1 Matter, Materials, Elements and Atoms (Link to “Materials”) Matter: anything that has mass and occupies space (e.g., water, air, wood, iron). Materials: substances we use to make things (e.g., plastic for buckets, aluminium for pans, clay for pots). Element: a pure substance made of only one type of atom (e.g., iron Fe, gold Au, oxygen O). Atom: the smallest particle of an element that still has the properties of that element.

Important idea: Different materials have different properties because their atoms (and how those atoms are arranged and bonded) are different.

2.2 Structure of the Atom (Sub-atomic Particles) An atom is made up of smaller particles called sub-atomic particles:

| Sub-atomic particle | Symbol | Charge | Location in atom | Relative mass (simple idea) | |---|---|---|---|---| | Proton | p⁺ | +1 (positive) | Nucleus (centre) | 1 | | Neutron | n⁰ | 0 (neutral) | Nucleus (centre) | 1 | | Electron | e⁻ | −1 (negative) | Shells/energy levels around nucleus | ~0 (very small) | The nucleus and shells Nucleus: dense centre of the atom containing protons and neutrons. Electron shells (energy levels): regions around the nucleus where electrons move.

Evaluation guide

• Explain an atom and its structure of an element using/linking it to the
• periodic table.
• List the sub-atomic particles found in the atom and indicate their
• location in the atom (e.g. proton, electron, neutron).