This chapter covers what matter is made of and how to count and describe its particles. It is the base for bonding, the periodic table and every mole calculation later in SPM Chemistry.
How do the lessons connect?
Each lesson needs an idea from the one before. Follow the order below the first time, then jump to the lesson you need when revising.
- Distinguishing atoms, ions and molecules: the three words every question uses.
- Calculating protons, neutrons and electrons: counting from the proton number and nucleon number.
- Interpreting isotopes and relative atomic mass: why atoms of one element can differ in mass.
- Explaining heating and cooling curves using particles: what the particles do as energy is added.
One sodium atom from start to finish
A sodium atom has 11 protons, 12 neutrons and 11 electrons, so it has no overall charge. It loses one electron to become Na⁺, which still has 11 protons and 12 neutrons but now 10 electrons.
That single idea links three lessons. Counting particles tells you the charge, the charge tells you it is an ion, and the ion is what appears in the formula NaCl. If any step feels shaky, return to the matching lesson.
Who should start where?
A new Form 4 student should begin at the first lesson and work in order. A Form 5 student who lost marks on isotopes or curves can go straight to that lesson and use the practice set to check.
If counting particles is easy but explaining graphs is not, try the atomic structure and periodic position practice tool. When you are ready for bigger calculations, continue to moles, formulas and equations.
To have a teacher work through this chapter with you, see online one-to-one Chemistry tuition.