1gPrinciples of Chemistry
Covalent bonding — Edexcel Linear - OL (Chemistry) Revision Notes & Topical Questions
5 min read 11 parts Lesson 9 of 25 1 quiz
Lesson summary
Covalent bonding Edexcel O Level Linear Chemistry notes: know that a covalent bond is formed between atoms by the sharing of a pair of electronsEach lone pair reduces bond angle by about 2.5°.Hydrogen bonding explains high bp of water and low density of ice.σ bonds form by head-o…
- Covalent bonding Edexcel O Level Linear Chemistry: what to do next
- Ionic bond
- Dative bond
- Metallic bond
- Electronegativity
- van der Waals (id–id)
Part 1 of 6Key ideas
Key ideas
Each lone pair reduces bond angle by about 2.5°.
Hydrogen bonding explains high bp of water and low density of ice.
σ bonds form by head-on overlap; π bonds by sideways overlap of p orbitals.
Part 2 of 6Syllabus points
1
know that a covalent bond is formed between atoms by the sharing of a pair of electrons
2
understand covalent bonds in terms of electrostatic attractions
3
understand how to use dot-and-cross diagrams to represent covalent bonds in
- - diatomic molecules
- including hydrogen, oxygen
- nitrogen
- halogens and hydrogen halides - inorganic molecules including water
- ammonia and carbon dioxide - organic molecules containing up to two carbon atoms
- including methane, ethane
- ethene and those containing halogen atoms
4
explain why substances with a simple molecular structures are gases or liquids, or solids with low melting and boiling points the term intermolecular forces of attraction can be used to represent all forces between molecules
5
explain why the melting and boiling points of substances with simple molecular structures increase, in general, with increasing relative molecular mass
6
explain why substances with giant covalent structures are solids with high melting and boiling points
7
explain how the structures of diamond, graphite and C60 fullerene influence their physical properties, including electrical conductivity and hardness
8
know that covalent compounds do not usually conduct electricity
Part 3 of 6Process & sequence
Structure types
Giant ionic NaCl – high mp, conducts molten
Simple molecular I₂ – low mp
Giant covalent diamond, SiO₂ – very high mp
Giant metallic Cu – conducts, malleable
- Lone pair–lone pair
- >
- lone pair–bond pair
- >
- bond pair–bond pair
Part 4 of 6Summary
Summary
Water has a bond angle of 104.5°.
Hydrogen bonds form with N, O or F.
Part 5 of 6Keep going
Covalent bonding Edexcel O Level Linear Chemistry: what to do next
These Covalent bonding Edexcel O Level Linear Chemistry notes covered the key ideas, worked examples and exam technique for this topic. Check your Covalent bonding Edexcel O Level Linear Chemistry understanding with the practice questions below, then reread any Covalent bonding Edexcel O Level Linear Chemistry point you were unsure about before moving on.
2
Previous lesson: 1f Ionic bonding — Notes
5
Official syllabus: Pearson Edexcel International GCSEs
Part 6 of 6Compare: Compare
| Bonding pairs | Lone pairs | Shape | Bond angle | Example | Polar? |
|---|---|---|---|---|---|
| 2 | 0 | Linear | 180° | CO₂ | No |
| 3 | 0 | Trigonal planar | 120° | BF₃ | No |
| 4 | 0 | Tetrahedral | 109.5° | CH₄ | No |
| 3 | 1 | Pyramidal | 107° | NH₃ | Yes |
| 2 | 2 | Non-linear (bent) | 104.5° | H₂O | Yes |
| 6 | 0 | Octahedral | 90° | SF₆ | No |
Key terms
Command terms
Command terms
Give / State / Name
Recall a fact; one idea per mark.
Define
Give the exact meaning using the specification keywords.
Describe
Give an account of what happens / the pattern in data, quoting values; no reasons needed.
Explain
Give reasons with linked statements (cause → effect). Each linked step is usually a separate marking point.
Suggest
Use knowledge in a new context; more than one answer may be accepted.
Compare
Similarities and differences; each point must refer to both items.
Calculate
Show working; include units; check significant figures. Method marks are given even if the final answer is wrong.
Discuss
Explore the issue from different angles and link the points.
Evaluate / Assess
Weigh strengths and weaknesses and reach a supported judgement.
Deduce
Draw a conclusion from the information given.
Justify
Support a statement/choice with evidence.
Exam technique
Keywords the mark scheme looks for in this lesson
Keywords the mark scheme looks for in this lesson
Ionic bond · Covalent bond · Dative bond · Metallic bond · Electronegativity · VSEPR · Hydrogen bond · van der Waals (id–id)
Learn each definition in the Key words tab exactly; a missing keyword in a definition usually loses the mark.
How to get full marks (examiner guidance)
How to get full marks (examiner guidance)
Use specification keywords exactly (e.g. electronegativity, nucleophile, dynamic equilibrium, activation energy).
Link ideas
Link ideas for “explain” each marking point is usually a cause → consequence step; unlinked facts often score nothing.
Use the information in the question
“discuss/evaluate” answers must use the data provided and match the number of marks.
Convert units carefully (mg → g, cm³ → dm³) and show working for calculations.
Avoid vague words
“it”, “stuff”, “things”, “goes up”, “energy is made”. Name the substance and the process.
Do not extrapolate a graph line beyond the data or to zero unless asked.
Six-mark extended responses are marked on content AND a logical, linked line of reasoning.
Marked practiceQuizzes for this lesson
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