2.1Chemical Bonding, Application Of Chemical Reactions and Organic Chemistry
Bonding, Structure and Properties — WJEC GCSE Chemistry Revision Notes & Topical Questions
10 min read 23 parts Lesson 1 of 7
Complete PDF with figures and original page layoutPage 1 WJEC GCSE Chemistry Your notes 2.1 Bonding, Structure & Properties Contents Properties of Substances Metallic Bonding Ionic Bonding Giant Ionic Structures Covalent Bonding Intermo…
Part 1 of 7Types of substance and bulk properties
- Types
- ionic, metallic, simple molecular covalent and giant covalent
- Bulk properties
- electrical conductivity and melting or boiling points come from many particles acting together, not from single atoms
| Type | Example | Conducts? | Melting / boiling point | Explanation |
|---|---|---|---|---|
| Ionic | Sodium chloride | No when solid, yes when molten or aqueous | High | Strong electrostatic attraction between oppositely charged ions; ions free to move when molten or dissolved |
| Simple molecular | Carbon dioxide | No | Low | Weak intermolecular forces; no free charged particles |
| Giant covalent | Graphite, diamond, fullerenes | No (except graphite and fullerenes) | High | Strong covalent bonds between atoms; graphite and fullerenes have delocalised electrons |
| Metallic | Copper, sodium | Yes | High | Strong attraction between metal ions and delocalised electrons; electrons free to move |
Part 2 of 7Metallic bonding
- Structure
- metals have giant lattices in which atoms lose their outer electrons and become positive metal ions
- Delocalised electrons
- the outer electrons belong to no one atom and form a "sea of electrons"
- Metallic bond = the strong force of attraction between positive metal ions and delocalised electrons
- Occurrence
- in metals and alloys, which are mixtures of metals
Part 3 of 7Properties of metals
- High melting and boiling points
- strong electrostatic forces between the ions and delocalised electrons need a lot of energy to break
- Conduction
- delocalised electrons move through the whole structure and carry charge, so metals conduct heat and electricity
- Malleability
- layers of ions slide over each other when a force is applied, so metals can be hammered into shape
- Higher tier
- melting point increases across a period
- (sodium, magnesium, aluminium)
- The number of delocalised electrons increases.
- The attraction to the positive ions is greater, so more energy is needed.
- melting point increases across a period
- Wording
- electrons move "through" the structure, not "throughout" it
Part 4 of 7Formation of ions
- Ion = a charged atom or group of atoms formed by loss or gain of electrons
- Purpose
- to obtain a full outer shell, so Group 1, 2, 6 and 7 ions have a noble gas configuration
- Cations
- positive ions formed when atoms lose electrons, so they have more protons than electrons
- Anions
- negative ions formed when atoms gain electrons, so they have more electrons than protons
- Pattern
- metals lose electrons and non-metals gain electrons
- Charge
- it equals the number of electrons lost or gained, so Mg loses 2 to give 2+ and Br gains 1 to give 1-
- Ionic bond
- the strong electrostatic attraction between oppositely charged ions holds an ionic compound together
Part 5 of 7Dot and cross diagrams for ionic compounds
- Purpose
- they show the arrangement of electrons in the compound
- Notation
- electrons from one atom are dots and from the other are crosses, so transfer is clear
- Charges
- each ion is in brackets with its charge at the top right
- Sodium chloride
- sodium transfers its outer electron to chlorine, giving [Na]+ and [Cl]- with a full outer shell of 8
Part 6 of 7Giant ionic structures
- Lattice
- a regular arrangement of alternating positive and negative ions, tightly packed
- Forces
- strong electrostatic attraction acts in all directions between oppositely charged ions
- Models
- ball-and-stick and 3D space-filling models represent the lattice
- High melting and boiling points
- the strong forces in all directions need a lot of energy to overcome
- Solid conductivity
- ions are in fixed positions, so solids are poor conductors
- Molten or dissolved conductivity
- ions can move and carry charge
- Higher tier
- greater ion charge means a stronger force and a higher melting point
- Magnesium oxide (Mg2+ and O2-) melts higher than sodium chloride (Na+ and Cl-).
- Wording
- say the ions move and carry charge, not that electrons do
Part 7 of 7Covalent bonding
- Covalent bond = the sharing of a pair of electrons between non-metal atoms
- Purpose
- each atom gains a full outer shell, giving a noble gas configuration
- Structures
- covalent substances may be small molecules or giant molecules
- Dot-and-cross diagrams
- electrons from one atom are dots and from the other are crosses, with shared electrons in the overlap of the shells
- Single bonds
- each pair of adjacent atoms shares one pair
- Hydrogen, chlorine, water, methane, ammonia and hydrogen chloride all have single bonds.
- The first shell holds only 2 electrons.
- Higher tier
- multiple bonds
- A double bond is two shared pairs, as in carbon dioxide and oxygen.
- A triple bond is three shared pairs, as in nitrogen.
Key terms
| Term | Meaning |
|---|---|
| Delocalised electrons | Outer electrons that are free to move through a metal structure. |
| Ionic bond | The electrostatic attraction between oppositely charged ions. |
| Covalent bond | A shared pair of electrons between non-metal atoms. |
| Lattice | A regular, repeating arrangement of particles. |
| Cation | A positive ion. |
| Anion | A negative ion. |
Avoid these mistakes
- Saying ionic compounds conduct because electrons move — in molten or dissolved form, ions move.
- Saying electrons move "throughout" a metal — they move through the structure.
- Saying covalent bonds form between metals — they form between non-metal atoms.
- Drawing a first shell with more than 2 electrons — the first shell holds only 2.
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🌳 Student Search Tree & Frequently Asked Exam Questions: bonding, structure and properties
Step-by-step problem-solving guide, mark scheme criteria, and experimental error analysis curated by Dr. Khaled Dabour (DABOURHUB).
1. Identify all given values and convert non-standard units, 2. State the primary formula or physiological/chemical principle, 3. Calculate to 3 significant figures and clearly state units.
Avoid confusing independent vs dependent variables in practical questions. In calculation questions, double-check percentage change formula: (change / original) × 100.
Where can I find bonding, structure and properties past paper questions by topic with the mark scheme?
On DABOURHUB every bonding, structure and properties question is grouped by syllabus point and shown with the mark-scheme wording, so you can see exactly which sentence earns the mark instead of scrolling through whole year papers.
What is the most common bonding, structure and properties exam question and why do students lose marks on it?
The repeated pattern on IGCSE papers is a short stem that asks you to apply bonding, structure and properties and then justify it with a command word (explain, suggest, compare). Marks are lost by stating the fact without linking it back to the wording of the question, so each bonding, structure and properties item here is written as a full-mark answer.
Is there an alternative to Save My Exams or Physics and Maths Tutor for bonding, structure and properties?
Yes: the bonding, structure and properties notes, topical questions and MCQ quizzes on this site follow the same syllabus headings as the official specification, and they open straight from the search result with no download step.
How do I revise bonding, structure and properties in two weeks before the exam?
Three passes: read the bonding, structure and properties notes once, then do the topical questions and mark them against the mark scheme, then redo only the ones you missed. The quiz on the page gives instant feedback so the third pass takes minutes rather than an evening.