AQA · GCSE · Chemistry
Course version: 8462 · Version from Sept 2018
When metals react with other substances the metal atoms form positive ions.
Full specification wording
The reactivity series: When metals react with other substances the metal atoms form positive ions.
This statement explains what happens to metal atoms during chemical reactions.
Checked against the AQA 8462 specification (opens in a new tab) on .
- Point 1 of 7
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
This statement explains what happens to metal atoms during chemical reactions. Metal atoms lose one or more outer-shell electrons and become positively charged ions. For example, a sodium atom loses one electron to form Na⁺, a magnesium atom loses two electrons to form Mg²⁺, and an aluminium atom loses three electrons to form Al³⁺. The number of positive charges equals the number of electrons lost, which matches the group number for many metals. This ion formation is the key behaviour that underlies the reactivity series: the more readily a metal loses electrons, the more reactive it is. You should be able to write the ion formed by a named metal, relate the charge to electrons lost, and explain that the positive ion is produced because protons outnumber electrons after loss. This idea supports later work on displacement, electrolysis and ionic bonding.
What earns the marks
- Metal atoms lose electrons when they react, forming positive ions.
- The charge on the ion equals the number of electrons lost by the atom.
- Examples include Na⁺, Mg²⁺ and Al³⁺, with charges matching electrons lost.
- The loss of negatively charged electrons leaves more protons than electrons, giving a net positive charge.
- The tendency of a metal to form positive ions is linked to its position in the reactivity series.
Common mistakes and how to put them right
Writing ion charges without the correct magnitude, such as giving magnesium a 1⁺ charge.
Put it right by counting the electrons lost, so magnesium forms Mg²⁺.
Saying metal atoms gain electrons to become positive ions.
Put it right by stating that metals lose electrons, since gaining electrons would give negative ions.
Confusing the ion charge with the group number for every element without checking.
Put it right by working out electron loss from the atom's electron arrangement.
Exam tips
- Use the group number of the metal to predict how many electrons are lost and therefore the ion charge.
- Write the charge as a superscript after the symbol, for example Mg²⁺, and check the number of positive charges matches electrons lost.
- If asked to explain, refer to loss of electrons and the resulting imbalance between protons and electrons.
Try the lesson
The start of the The reactivity series: When metals react with other substances the metal atoms form positive ions. lesson, made from checked teaching notes for this specification point.
Have a go first
When a metal atom reacts, what type of ion does it form?
Listen
This statement explains what happens to metal atoms during chemical reactions. Metal atoms lose one or more outer-shell electrons and become positively charged ions. For example, a sodium atom loses one electron to form Na⁺, a magnesium atom loses two electrons to form Mg²⁺, and an aluminium atom loses three electrons to form Al³⁺. The number of positive charges equals the number of electrons lost, which matches the group number for many metals. This ion formation is the key behaviour that underlies the reactivity series: the more readily a metal loses electrons, the more reactive it is. You should be able to write the ion formed by a named metal, relate the charge to electrons lost, and explain that the positive ion is produced because protons outnumber electrons after loss. This idea supports later work on displacement, electrolysis and ionic bonding. A strong answer earns marks for these points. Metal atoms lose electrons when they react, forming positive ions. The charge on the ion equals the number of electrons lost by the atom. Examples include Na⁺, Mg²⁺ and Al³⁺, with charges matching electrons lost. The loss of negatively charged electrons leaves more protons than electrons, giving a net positive charge. A common slip: Writing ion charges without the correct magnitude, such as giving magnesium a 1⁺ charge. Instead, counting the electrons lost, so magnesium forms Mg²⁺. Exam tip: Use the group number of the metal to predict how many electrons are lost and therefore the ion charge.
See it
Key words
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Ion formation by metals
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Electron loss and positive charge
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Link between ion formation and reactivity
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Representing ions with symbols and charges
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See every definition
- Ion formation by metals
- When metals react with other substances the metal atoms form positive ions.
- Electron loss and positive charge
- Metal atoms lose one or more outer-shell electrons and become positively charged ions, because the loss of negatively charged electrons leaves more protons than electrons.
- Link between ion formation and reactivity
- The more readily a metal loses electrons, the more reactive it is, and this ion formation underlies the reactivity series.
- Representing ions with symbols and charges
- The charge on the ion equals the number of electrons lost by the atom, written as a superscript after the symbol, such as Na⁺, Mg²⁺ and Al³⁺.
Label the diagram
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