Starter quiz
- Match the keyword to the correct statement.
- salts⇔Ionic compounds formed from positive and negative ions. ✓
- halide⇔A salt formed from a halogen. ✓
- diatomic elements⇔Two atoms of the same type chemically bonded together. ✓
- Group 7⇔Non metallic elements which react with metals to form halide salts. ✓
- Which trends occur in Group 7 elements going down the group?
- melting points decrease
- melting points increase ✓
- boiling points increase ✓
- boiling points decrease
- size of atoms and molecules decrease
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- What happens to the forces of attraction between atoms going down Group 7?
- they become stronger ✓
- they become weaker
- they stay the same
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- Going down Group 7, the molecules become more ______ packed together and density increases.
- 'tightly' ✓
- Place the halogens in order of their density at room temperature. Place the least dense halogen first.
- 1⇔fluorine
- 2⇔chlorine
- 3⇔bromine
- 4⇔iodine
- 5⇔astatine
- Which statement explains why reactivity decreases down Group 7?
- It becomes more difficult to gain an electron as the size of the atom increases. ✓
- It becomes easier to gain an electron as the size of the atom increases.
- The distance of the outer electron from the nucleus decreases.
- The distance of the outer electron from the nucleus increases. ✓
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Exit quiz
- Which of these halogens is the least reactive?
- fluorine
- bromine
- iodine ✓
- chlorine
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- What products are formed when chlorine gas is bubbled through a solution of lithium bromide?
- bromine and lithium
- lithium chloride and bromine ✓
- chlorine and lithium bromide
- no reaction takes place
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- Choose the chemical test which would indicate chlorine gas was present.
- Turns damp red litmus paper blue.
- Produces a squeaky pop sound when a lit splint is exposed to the gas.
- Damp blue litmus paper stays blue.
- Turns damp blue litmus paper red, then bleaches white. ✓
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- What happens when halogen atoms react to form halide salts?
- They gain an outer electron. ✓
- They lose an outer electron.
- They become stable negative ions. ✓
- They become stable positive ions.
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- What happens when a halogen and a Group 1 metal react?
- A Group 1 atom transfers an outer electron to a Group 7 atom. ✓
- A Group 7 atom transfers an outer electron to a Group 1 atom.
- Oppositely charged ions are formed which electrostatically attract each other. ✓
- Identically charged ions are formed which electrostatically attract each other.
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- Choose the correct word equation to show the displacement reaction between bromine and potassium chloride.
- bromine + potassium chloride → bromine + potassium chloride ✓
- bromine + potassium chloride → bromide + potassium chlorine
- bromine + potassium chloride → chlorine + potassium bromide
- bromine + potassium chloride → potassium + bromine chloride
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Worksheet
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Lesson Details
Key learning points
- Halogens can be dissolved in water to form acidic solutions.
- A more reactive halogen can displace a less reactive one from a compound.
- Group 7 elements react with Group 1 and 2 metals to form salts.
- The chemical test for chlorine involves passing the gas over damp blue litmus paper.
Common misconception
Halogen solutions are coloured and sometimes it can be difficult to determine colour changes during displacement reactions.
Displacement of iodine gives the darkest colour change (turns brown), while bromine will provide one which is lighter (turns orange).
Keywords
Displacement - reaction is where a more reactive element replaces a less reactive element in a compound.
Solution - is formed when a substance dissolves in a liquid.
Halides - are the name of salts formed from halogens, e.g. sodium chloride (NaCl).
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