AQA · GCSE · Combined Science
Course version: 8464 · Version from Sept 2018
The charge on the ions produced by metals in Groups 1 and 2 and by…
Full specification wording
Ionic bonding: The charge on the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 relates to the group number of the element in the periodic table.
An element's group number predicts the charge on its ion.
Checked against the AQA 8464 specification (opens in a new tab) on .
- Point 4 of 5
- 4 key terms
Study notes
From the checked teaching notes for this specification point.
The idea
An element's group number predicts the charge on its ion. Metals in Group 1 lose their single outer electron and form 1⁺ ions, such as Na⁺ and K⁺. Metals in Group 2 lose two outer electrons and form 2⁺ ions, such as Mg²⁺ and Ca²⁺. Non-metals in Group 6 gain two electrons to complete their outer shell and form 2⁻ ions, such as O²⁻ and S²⁻. Non-metals in Group 7 gain one electron and form 1⁻ ions, such as Cl⁻ and Br⁻. The pattern arises because atoms gain or lose electrons to reach a full outer shell. For Group 1 and 2 metals, the positive charge equals the group number. For Group 6 and 7 non-metals, the negative charge equals eight minus the group number.
What earns the marks
- Group 1 metals form ions with a 1⁺ charge by losing one outer electron.
- Group 2 metals form ions with a 2⁺ charge by losing two outer electrons.
- Group 6 non-metals form ions with a 2⁻ charge by gaining two electrons.
- Group 7 non-metals form ions with a 1⁻ charge by gaining one electron.
- The charge follows from the number of electrons transferred to reach a full outer shell.
- The group number can be used to predict the charge for these groups without recalling each ion individually.
- Ion charges are written with the number before the sign, for example 2⁺ and 2⁻, and with the sign for single charges, for example Na⁺ and Cl⁻.
Common mistakes and how to put them right
Writing the sign before the number for ion charges, such as +2 instead of 2⁺.
Put it right: The correct format is number then sign.
Assuming all metals form positive ions with the same charge.
Put it right: Group 1 and Group 2 metals differ because they lose different numbers of electrons.
Giving Group 6 non-metals a 6⁻ charge by copying the group number.
Put it right: They gain two electrons, so the charge is 2⁻.
Exam tips
- Link each charge to the number of electrons lost or gained, not just to the group number.
- Check that the charge sign matches whether the element is a metal or a non-metal.
- Use the group number to predict charges for unfamiliar elements in Groups 1, 2, 6 and 7.
Try the lesson
The start of the Ionic bonding: The charge on the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 relates to the group number of the element in the periodic table. lesson, made from checked teaching notes for this specification point.
Have a go first
A potassium atom is in Group 1 of the periodic table. What is the charge on the ion that potassium forms?
Listen
An element's group number predicts the charge on its ion. Metals in Group 1 lose their single outer electron and form 1⁺ ions, such as Na⁺ and K⁺. Metals in Group 2 lose two outer electrons and form 2⁺ ions, such as Mg²⁺ and Ca²⁺. Non-metals in Group 6 gain two electrons to complete their outer shell and form 2⁻ ions, such as O²⁻ and S²⁻. Non-metals in Group 7 gain one electron and form 1⁻ ions, such as Cl⁻ and Br⁻. The pattern arises because atoms gain or lose electrons to reach a full outer shell. For Group 1 and 2 metals, the positive charge equals the group number. For Group 6 and 7 non-metals, the negative charge equals eight minus the group number. A strong answer earns marks for these points. Group 1 metals form ions with a 1⁺ charge by losing one outer electron. Group 2 metals form ions with a 2⁺ charge by losing two outer electrons. Group 6 non-metals form ions with a 2⁻ charge by gaining two electrons. Group 7 non-metals form ions with a 1⁻ charge by gaining one electron. Exam tip: Link each charge to the number of electrons lost or gained, not just to the group number.
See it
Key words
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Patterns in the periodic table
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Electron loss and gain to achieve full outer shells
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Predicting ion charges from group number
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Writing ionic charges with correct notation
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See every definition
- Patterns in the periodic table
- The charge on the ions produced by metals in Groups 1 and 2 and by non-metals in Groups 6 and 7 relates to the group number of the element.
- Electron loss and gain to achieve full outer shells
- Atoms gain or lose electrons to reach a full outer shell, and the charge follows from the number of electrons transferred.
- Predicting ion charges from group number
- The group number can be used to predict the charge for these groups without recalling each ion individually.
- Writing ionic charges with correct notation
- Ion charges are written with the number before the sign, for example 2⁺ and 2⁻, and with the sign for single charges.
Label the diagram
Some boxes have lost their names. Pick the right name for each number.
1Box 1
2Box 2
3Box 3
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