Chemistry: should I choose it?

What will I learn?

How will I be assessed?

Progression and companion subjects

No complete companion or exclusion review is attached to this profile. Check the official course-entry conditions, language eligibility and your school’s sequence before enrolling. Links between resource hubs show related learning; they do not establish a compulsory prerequisite.

Will I find it hard?

Difficulty depends on your experience, interests, teaching and assessment. These are our reflection prompts, not an official difficulty rating.

• Look at how much data, calculation and graph interpretation appear in the sample for this particular science.
• Can you explain the ideas in your own words as well as recall the terminology?
• Do investigations and evaluating evidence interest you? Check the course’s practical requirements.

Does it scale up or down?

Chemistry, 2025. Table 6 of QTAC’s 2025 report publishes separate raw and scaled subject medians for General subjects with at least 50 students. Historical cohort data cannot predict your result or a future scaling direction.

Scaling is not a measure of difficulty or a guaranteed bonus. Prioritise content you can engage with and required subjects for courses you are considering.

Try a little of the subject

Properties and structure of atoms

Every atom is built from a tiny, dense, positively charged nucleus surrounded by a much larger region occupied by electrons. The nucleus holds protons (charge +1, mass about 1 u) and neutrons (no charge, mass about 1 u). Electrons carry a charge of −1 and have a mass roughly 1/1836 of a proton, so almost all of an atom's mass sits in the nucleus while almost all of its volume is electron cloud. The Geiger–Marsden gold foil experiment supplied the key evidence: most alpha particles passed straight through thin gold foil, but a small fraction bounced back sharply, which only makes sense if positive charge and mass are concentrated in a very small centre. Later, Maria Goeppert Mayer's nuclear shell model showed that protons and neutrons are themselves arranged in energy levels, explaining why some nuclei are especially stable. The atomic number (Z) is the number of protons and defines the element. The mass number (A) is the total number of protons plus neutrons. In nuclear symbol notation the mass number is written as a superscript and the atomic number as a subscript before the symbol, for example ³⁵₁₇Cl; the same isotope can be written chlorine-35 or Cl-35. Neutrons = A − Z. For a neutral atom, electrons = protons; for an ion, subtract the charge from Z (a 2+ ion has two fewer electrons, a 3− ion has three more). Isotopes are atoms of the same element with different numbers of neutrons. Because they have identical electron configurations, isotopes react in the same way chemically, but they differ in mass-dependent physical properties such as density, rate of diffusion and nuclear stability. Unstable isotopes (radioisotopes) decay, which is useful: carbon-14 dating estimates the age of once-living material, and cobalt-60 or iodine-131 are used in radiotherapy. The relativ

Original practice question: Chlorine-35 (³⁵₁₇Cl) and chlorine-37 are isotopes. Which statement is correct?

This is ATARMAxxing’s original sample learning material. It is not an official assessment task or a prediction of your school’s workload.

Explore the resources

Open the Chemistry subject hub and free preview (opens in a new tab)

• Chemistry — QCE Units 3 & 4 (opens in a new tab)

Core subject information and planning are free. Full study resources are optional.