Starter quiz
- Which of the following subatomic particles are found in the nucleus of an atom?
- proton ✓
- neutron ✓
- electron
- ion
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- Match the following subatomic particles to the correct charge.
- proton⇔1+ ✓
- neutron⇔0 ✓
- electron⇔1– ✓
- Why do atoms have no overall charge?
- They contain the same number of protons as electrons. ✓
- They contain the same number of protons as neutrons.
- They contain the same number of neutrons as electrons.
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- Oxygen is in Group 6 of the periodic table. How many electrons does an oxygen atom have in its outer shell?
- '6' ✓
- A potassium atom has 19 electrons in total. How many electrons are there in the outer shell of a potassium atom?
- '1' ✓
- Sulfur is in Group 6, Period 3 on the periodic table. What does this tell you about sulfur?
- A sulfur atom has six electrons in its outer shell. ✓
- A sulfur atom has three electrons in its outer shell.
- A sulfur atom has three shells of electrons. ✓
- A sulfur atom has six shells of electrons.
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Exit quiz
- Match the following terms to their definitions.
- ion⇔An atom or molecule that has gained or lost electrons so has a charge. ✓
- cation⇔A positively charged ion. ✓
- anion⇔A negatively charged ion. ✓
- Atoms become more ______ when they have a full outer shell of electrons.
- 'stable' ✓
- When a magnesium atom forms an ion, it loses two electrons. What charge does a magnesium ion have?
- 2+ ✓
- 2–
- 1+
- 1–
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- Boron (B) is in Group 3 of the periodic table. Which of the following correctly represents a boron ion?
- B⁺
- B²⁺
- B³⁺ ✓
- B³⁻
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- Which of the following statements are correct?
- Non–metal atoms lose electrons to become more stable.
- Metal atoms lose electrons to become more stable. ✓
- An oxygen atom is reperesented by the symbol O²⁻.
- A calcium ion is represented by the symbol Ca²⁺. ✓
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- Chlorine is in Group 7 of the periodic table. What happens to a chlorine atom in order for it to form a stable chloride ion?
- It gains an electron to form a negative ion. ✓
- It loses an electron to form a negative ion.
- It gains an electron to form a positive ion.
- It loses an electron to form a positive ion.
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Worksheet
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Presentation
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Lesson Details
Key learning points
- Atoms are more stable when they have a full outer shell.
- Metal atoms become more stable when they lose the electron(s) in their outer shell, and become positive ions (cations).
- Non–metal atoms become more stable when they gain electrons to fill their outer shell and become negative ions (anions).
- Ions form through the loss or gain of electrons.
- Standard ion notation uses superscript charge values where the charge follows the number (e.g. 2+, not +2).
Common misconception
Ions are not formed because atoms 'want' or 'need' a full outer electron shell. Pupils often find standard notation difficult and get confused about when to use superscript and subscript.
It is important that pupils understand that atoms do not have 'wants' or 'needs'. Emphasise that the driving force for the formation of atoms is an increase in stability when the outer electron shell is full.
Keywords
Ion - An atom or molecule that has lost or gained one or more electrons so has a charge.
Cation - A positively charged ion.
Anion - A negatively charged ion.
Dot–and–cross diagram - Used to show how chemical bonds are formed between atoms – the electrons from one atom are shown as dots and the electrons from the other atom are shown as crosses.
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