AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
Ionic compounds are held together by strong electrostatic forces of…
Full specification wording
Ionic compounds: Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions.
In an ionic compound, positive and negative ions attract each other because opposite charges attract.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 2 of 6
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
In an ionic compound, positive and negative ions attract each other because opposite charges attract. These attractions act in all directions throughout the giant lattice and are called electrostatic forces of attraction. They are strong, so a large amount of energy is needed to overcome them. This is why ionic compounds have high melting points and high boiling points. For example, sodium chloride melts at about 801 °C because the Na⁺ and Cl⁻ ions are held in a strong three-dimensional network. When an ionic compound melts or dissolves, the lattice breaks down and the ions become free to move, which allows the molten or dissolved compound to conduct electricity.
What earns the marks
- Ionic compounds are held together by electrostatic forces of attraction between oppositely charged ions.
- The forces act between positive and negative ions throughout the giant lattice.
- The attractions are strong, so a large amount of energy is needed to break them.
- Strong electrostatic forces explain the high melting points and boiling points of ionic compounds.
- When melted or dissolved, the lattice breaks down and the ions are free to move.
- Free-moving ions allow molten or aqueous ionic compounds to conduct electricity.
Common mistakes and how to put them right
Saying ionic compounds are held together by covalent bonds.
Put it right: The bonding is electrostatic attraction between oppositely charged ions.
Describing the forces as weak.
Put it right: They are strong, which is why ionic compounds have high melting points.
Stating that solid ionic compounds conduct electricity.
Put it right: The ions are fixed in the lattice, so conduction occurs only when molten or dissolved.
Exam tips
- Use the phrase strong electrostatic forces of attraction between oppositely charged ions.
- Link the strength of the forces to a named property such as high melting point.
- Explain conduction by referring to ions being free to move when molten or in solution.
Try the lesson
The start of the Ionic compounds: Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions. lesson, made from checked teaching notes for this specification point.
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What holds the ions together in an ionic compound?
Listen
In an ionic compound, positive and negative ions attract each other because opposite charges attract. These attractions act in all directions throughout the giant lattice and are called electrostatic forces of attraction. They are strong, so a large amount of energy is needed to overcome them. This is why ionic compounds have high melting points and high boiling points. For example, sodium chloride melts at about 801 °C because the Na⁺ and Cl⁻ ions are held in a strong three-dimensional network. When an ionic compound melts or dissolves, the lattice breaks down and the ions become free to move, which allows the molten or dissolved compound to conduct electricity. A strong answer earns marks for these points. Ionic compounds are held together by electrostatic forces of attraction between oppositely charged ions. The forces act between positive and negative ions throughout the giant lattice. The attractions are strong, so a large amount of energy is needed to break them. Strong electrostatic forces explain the high melting points and boiling points of ionic compounds. Exam tip: Use the phrase strong electrostatic forces of attraction between oppositely charged ions.
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Key words
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Electrostatic attraction between oppositely charged ions
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Strength of ionic bonding
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Relationship between bonding and physical properties
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Conduction by free-moving ions
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See every definition
- Electrostatic attraction between oppositely charged ions
- Ionic compounds are held together by strong electrostatic forces of attraction between oppositely charged ions, which attract each other because opposite charges attract.
- Strength of ionic bonding
- The attractions are strong, so a large amount of energy is needed to overcome them.
- Relationship between bonding and physical properties
- Strong electrostatic forces explain the high melting points and high boiling points of ionic compounds.
- Conduction by free-moving ions
- When an ionic compound melts or dissolves, the lattice breaks down and the ions become free to move, which allows the molten or dissolved compound to conduct electricity.
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