- Where Topic: Key concepts in chemistry sits under the official 2026 Edexcel Chemistry syllabus
- The 53 subtopics beneath it, each on its own page
- A direct route to the free Chemistry past papers — every session, question paper and mark scheme
- Free to browse, free to link — no signup, no paywall
- Cross-linked to Topical Solved, the paid version that groups this topic's questions and works each one through
Pearson Edexcel · GCSE · Chemistry
1 Key concepts in chemistry Topical Past Papers
Pearson Edexcel GCSE Chemistry — where "Key concepts in chemistry" sits in the official 2026 Edexcel specification, and the free past papers that examine it.
Pearson Edexcel GCSE Chemistry topical past papers — Topic: Key concepts in chemistry — free, no signup. The official syllabus entry for this topic — the questions that examine it are in the free Chemistry past papers, linked from this page. This topic breaks into 53 subtopics under the official syllabus numbering. A free syllabus map for this topic, with the Chemistry past papers it is examined in one click away. No signup, no paywall.
What this Chemistry topic page covers
This is the Edexcel GCSE Chemistry syllabus entry for Topic: Key concepts in chemistry — where the topic sits under the official 2026 syllabus numbering, and what falls under it. It is a map of the topic, free to browse and free to link.
The questions themselves are in the Chemistry past papers, and those are free here too — the full archive, session by session, each paper with its official mark scheme. This page does not reproduce them; it points you at the subject's archive so you can work the sessions that cover this topic.
Where to find the Chemistry questions on this topic
Every question Edexcel has ever set on this topic is inside the Chemistry past papers themselves — and the complete Edexcel GCSE Chemistry archive is free on this site. Each session gives you the question paper and its official mark scheme, so you can attempt a question and mark yourself without paying for anything.
Working from the raw sessions means opening several papers to cover one topic. If you would rather have this topic's questions already pulled together, with the method shown step by step instead of only an acceptable answer, that is what Topical Solved is — the paid version of this same topic.
- Open the free Chemistry past-paper archive — every session, question paper and mark scheme.
- Work the sessions that cover this topic, then mark yourself against the official mark scheme.
- Want this topic's questions collected and worked through? Topical Solved does exactly that.
- Nothing on this page is behind a signup or a paywall.
Kept current with the 2026 syllabus
Edexcel releases new Chemistry sessions every year, and every one of them lands in the free Chemistry past-paper archive on this site — question paper and official mark scheme together, usually within days of release. Nothing about that is gated.
This topic map is rebuilt against the official 2026 Edexcel Chemistry syllabus, so the numbering and the topic titles here match the specification a student is actually sitting rather than a retired version of it. Stale topic mapping is one of the biggest hidden quality problems with free past-paper sites, and it is the thing this page is here to get right.
Chemistry topical past papers — what students search for
Students search for "Chemistry topical past papers", "Chemistry topic-wise questions", "Chemistry chapter-wise past papers", "Chemistry questions by topic", "free Edexcel Chemistry past papers by topic", and dozens more variations every day. What almost all of them are really asking is a syllabus question first: which topic is this, and which papers examine it. That is what this page answers, and it links straight to the free papers.
Common searches — "Chemistry 2026 paper", "Chemistry recent past papers", "Chemistry latest questions by topic" — are all served by the free Edexcel Chemistry past-paper archive, which carries every session with its official mark scheme at no cost.
Some students search specifically for "Chemistry questions only no solutions" or "Chemistry past papers without answers" — the free session archive is exactly that. If you want "Chemistry worked solutions" or "Chemistry step-by-step", Topical Solved collects this topic's questions and shows a teacher-verified working for each one.
Subtopics within Key concepts in chemistry
Describe how the Dalton model of an atom has changed over
Describe the structure of an atom as a nucleus containing
Recall the relative charge and relative mass of:
Explain why atoms contain equal numbers of protons and
Describe the nucleus of an atom as very small compared to the
Recall that most of the mass of an atom is concentrated in the
Recall the meaning of the term mass number of an atom
Describe atoms of a given element as having the same number
Describe isotopes as different atoms of the same element
Calculate the numbers of protons, neutrons and electrons in
Explain how the existence of isotopes results in relative atomic
Calculate the relative atomic mass of an element from
Describe how Dmitri Mendeleev arranged the elements, known
Describe how Dmitri Mendeleev used his table to predict the
Explain that Dmitri Mendeleev thought he had arranged
Explain the meaning of atomic number of an element in terms
Describe that in the periodic table
Identify elements as metals or non-metals according to their
Predict the electronic configurations of the first 20 elements in
Explain how the electronic configuration of an element is related
Explain how ionic bonds are formed by the transfer of electrons
Recall that an ion is an atom or group of atoms with a positive
Calculate the numbers of protons, neutrons and electrons in
Explain the formation of ions in ionic compounds from their
Explain the use of the endings –ide and –ate in the names of
Deduce the formulae of ionic compounds (including oxides
Explain the structure of an ionic compound as a lattice structure
Explain how a covalent bond is formed when a pair of electrons
Recall that covalent bonding results in the formation of
Recall the typical size (order of magnitude) of atoms and small
Explain the formation of simple molecular, covalent substances
Explain why elements and compounds can be classified as:
Explain the properties of ionic compounds limited to:
Explain the properties of typical covalent, simple molecular
Recall that graphite and diamond are different forms of carbon
Describe the structures of graphite and diamond
Explain, in terms of structure and bonding, why graphite is used
Explain the properties of fullerenes including C60 and graphene
Describe, using poly(ethene) as the example, that simple
Explain the properties of metals, including malleability and the
Describe the limitations of particular representations and
Describe most metals as shiny solids which have high melting
Calculate:
Calculate the formulae of simple compounds from reacting
Deduce:
Describe an experiment to determine the empirical formula of a
Explain the law of conservation of mass applied to:
Calculate masses of reactants and products from balanced
Calculate the concentration of solutions in g dm–3
Recall that one mole of particles of a substance is defined
Calculate the number of:
Explain why, in a reaction, the mass of product formed is
Deduce the stoichiometry of a reaction from the masses
Frequently Asked Questions
Are the questions for this topic on this page?
No — this page is the syllabus map for the topic: its official numbering, its subtopics, and a route to the papers that examine it. The questions live in the Edexcel Chemistry past papers, which are free on this site with the official mark scheme beside every session. If you want this topic's questions collected in one place and worked through step by step, that is the paid Topical Solved product.
What's the difference between this and Topical Solved?
This page is free and it maps the topic: where it sits in the official syllabus, what falls under it, and where to find the papers that examine it. Topical Solved is the paid product that does the collecting for you — this topic's past-paper questions pulled together with a teacher-verified, step-by-step worked solution for each one, so you can see exactly how the marks are earned.
Is the mark scheme included?
Yes, in the free Chemistry past-paper archive this page links to: every session there carries its official mark scheme alongside the question paper, free to open, so you can attempt a question and mark your own answer.
How up to date is the Chemistry archive?
New Edexcel Chemistry sessions are added to the free past-paper archive as they are released, and this topic map is rebuilt against the official 2026 syllabus so its numbering matches the specification being sat — not a retired version of it.