What does the structure, bonding and introductory organic block of Edexcel Chemistry cover?

This block is Topics 1 to 6 of the Edexcel 9CH0 specification: atomic structure and the periodic table, bonding and structure, redox I, inorganic chemistry and the periodic table (Group 2 and Group 7), formulae, equations and amounts of substance (the moles toolkit), and the introductory organic chemistry of alkanes and alkenes. Together they are the foundation for every later topic.

Which topic is the most important to master first?

Formulae, equations and amounts of substance (Topic 5) is the most reused in the whole qualification. Moles calculations underpin almost every quantitative question, so master mass, concentration, gas volume, empirical formulae, titrations, percentage yield and atom economy before anything else.

How is this block examined in Edexcel Chemistry?

These topics appear across all three papers. Expect multiple-choice and short calculation questions on moles, oxidation numbers and shapes, structured questions on ionisation-energy trends and Group 2 and 7 reactions, and the first organic mechanisms (free-radical substitution and electrophilic addition). The content is built on in Papers 1 and 2 throughout the course.

What is the most common mistake in the early Edexcel topics?

Getting the 4s and 3d order wrong on ionisation: 4s fills first but is removed first, so Fe2+ is 3d6 not 3d4 4s2. Other frequent errors are saying a polar bond means a polar molecule, forgetting lone-pair repulsion when stating bond angles, and reading orders or reactivity trends the wrong way.

EnglandChemistry

Edexcel A-Level Chemistry: Structure, Bonding and Introductory Organic (Topics 1-6) overview

A deep-dive overview of the first six topics of Edexcel A-Level Chemistry (9CH0): atomic structure, bonding, redox, inorganic periodicity, the moles toolkit, and introductory organic chemistry of alkanes and alkenes.

Generated by Claude Opus 4.818 min read9CH0Updated 2026-06-02

Reviewed by: AI editorial process; not yet individually human-reviewed

Jump to a section

What this block demands
Atomic structure and bonding
Redox and periodicity
The moles toolkit and introductory organic
How this block is examined
Check your knowledge

What this block demands

The first six topics of Edexcel A-Level Chemistry build the foundation for the entire qualification. They move from the structure of the atom, through bonding and the periodic table, into the quantitative moles toolkit, and finally into the first organic chemistry. The examiners test precise recall of definitions and trends alongside confident calculation.

This guide walks through Topics 1 to 6 in specification order and sets out the exam patterns Edexcel repeats. Each topic has a matching dot-point page with practice questions; this overview ties them together.

Atomic structure and bonding

Topic 1 (Atomic structure) covers protons, neutrons and electrons, isotopes and mass spectrometry, electron configuration in s, p and d sub-shells, and the ionisation-energy evidence for shells and sub-shells. The recurring exam point is that first ionisation energy rises across a period and falls down a group, with small dips that reveal sub-shells.

Topic 2 (Bonding and structure) classifies bonding as ionic, covalent (including dative) and metallic, uses electronegativity to judge polarity, predicts molecular shapes from electron-pair repulsion, and links the four crystal structures to physical properties. Remember that a polar bond does not always mean a polar molecule.

Redox and periodicity

Topic 3 (Redox I) establishes oxidation numbers, the electron-transfer definitions (OIL RIG), oxidising and reducing agents, half-equations and disproportionation. Topic 4 (Inorganic chemistry and the periodic table) covers periodicity across Period 3 and the trends and reactions of Group 2 (reactivity increases down the group) and Group 7 (reactivity decreases down the group), plus the silver-nitrate test for halides.

The moles toolkit and introductory organic

Topic 5 (Formulae, equations and amounts of substance) is the calculation engine: the mole, $n = \frac{m}{M_r}$ , $n = c \times V$ , the ideal gas equation $pV = nRT$ , empirical and molecular formulae, titrations, percentage yield and atom economy. Topic 6 (Organic chemistry I) introduces nomenclature and isomerism, alkane combustion and free-radical substitution, and alkene electrophilic addition (with Markownikoff's rule) and addition polymerisation.

How this block is examined

A typical Edexcel profile for Topics 1 to 6:

Multiple choice and short answer. Assigning oxidation numbers, identifying shapes and bond angles, recalling definitions, and selecting halide test results.
Calculations. Relative atomic mass from mass spectra, moles and titrations, empirical formulae, percentage yield and atom economy.
Applied and trend questions. Explaining ionisation-energy trends, Group 2 and 7 reactivity, and predicting the major product of electrophilic addition.
Mechanisms. Free-radical substitution (initiation, propagation, termination) and electrophilic addition.

Check your knowledge

A mix of recall and calculation questions across Topics 1 to 6. Attempt them under timed conditions, then check against the solutions.

State what is meant by the first ionisation energy. (2 marks)
State and explain the shape and bond angle of a water molecule. (3 marks)
Determine the oxidation number of chromium in $Cr_2O_7^{2-}$ . (2 marks)
Describe how silver nitrate and ammonia distinguish chloride from iodide ions. (3 marks)
Calculate the number of moles in $8.0\ \text{g}$ of sodium hydroxide ( $M_r = 40$ ). (1 mark)
Predict the major product of propene reacting with $HBr$ and justify it. (3 marks)

Solutions

Q1: The energy needed to remove one electron from each atom in one mole of gaseous atoms: $X(g) \rightarrow X^+(g) + e^-$ .
Q2: Bent (V-shaped), $104.5^\circ$ . There are two bonding pairs and two lone pairs; lone pairs repel more than bonding pairs, reducing the angle from the tetrahedral $109.5^\circ$ .
Q3: Oxygen is $-2$ , so $2x + 7(-2) = -2$ , giving $x = +6$ .
Q4: Acidify with dilute nitric acid, then add silver nitrate: chloride gives a white precipitate that dissolves in dilute ammonia; iodide gives a yellow precipitate that is insoluble even in concentrated ammonia.
Q5: $n = \frac{8.0}{40} = 0.20\ \text{mol}$ .
Q6: 2-bromopropane. By Markownikoff's rule the hydrogen adds to the carbon with more hydrogens, forming the more stable secondary carbocation intermediate, which gives the major product.

Sources & how we know this

Pearson Edexcel A-Level Chemistry (9CH0) specification — Pearson Edexcel (2015)