Protons, Neutrons, Electrons, Elements and Compounds
From the basic structure of the atom to isotopes, this exam covers everything you need to know about matter at the subatomic level. Primary tackles essential concepts; Secondary goes deeper with atomic number, mass number and the difference between element and compound.
Physics & Chemistry · Primary, Secondary
Primary learns that atoms have a nucleus and electrons, that molecules are bonded atoms. Secondary adds protons, neutrons, Z, A and isotopes. The progression is natural.
Understanding atomic number Z is the key to reading the periodic table. This exam and the Periodic Table exam complement each other perfectly.
H₂O has 2 hydrogens and 1 oxygen: 3 atoms in total. Questions teach students to read chemical formulae before they appear in other exams.
"A Year 10 student who did not understand isotopes sees the ¹²C and ¹⁴C question: same number of protons (carbon), different number of neutrons. In that moment it clicks."
Tricks and techniques to master this topic faster:
Proton(+) and neutron(no charge) go in the nucleus. Electron(-) orbits outside. A mental image beats memorising.
Atomic number Z = number of protons = what defines the element. Mass number A = protons + neutrons.
To calculate neutrons: N = A − Z. If carbon has A=12 and Z=6, it has 6 neutrons.
Isotopes = same element (same Z), different A (different number of neutrons). Example: ¹²C and ¹⁴C are both carbon.
If you are studying Atoms & Molecules — Atomic Structure, these curriculum topics complement each other:
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