Starter quiz
- Match the following elements to their symbols.
- Fluorine⇔F ✓
- Chlorine⇔Cl ✓
- Iodine⇔I ✓
- Astatine⇔At ✓
- Bromine⇔Br ✓
- Identify potassium bromide from the list of chemical formulae
- KBr ✓
- PBr
- KB
- BrP
- PbR
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- What is the name given to Group 7 on the periodic table?
- Salts
- Metals
- Noble gases
- Halogens ✓
- Alkali metals
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- Which term is used to correctly describe an element that exists as a molecule composed of two atoms bonded together?
- Monatomic
- Diatomic ✓
- Biatomic
- Bionic
- Dibond
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- Which of these Group 7 elements will have the largest relative atomic mass?
- I ✓
- F
- Br
- Cl
-
- Which Group 7 element has 35 protons, 35 electrons and 45 neutrons?
- Iodine
- Chlorine
- Bromine ✓
- Fluorine
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Exit quiz
- Match the halogen to an example of one of its uses.
- Fluorine⇔added to toothpaste to prevent tooth decay ✓
- Chlorine⇔added to tap water to kill harmful microbes present ✓
- Iodine⇔as an antiseptic to treat wounds ✓
- When a bromine atom forms a bromide ion, it gains an electron. Which is the correct ion?
- Br ⁻ ✓
- Br²⁻
- Br₂
- Br₂ ⁻
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- Match the melting point to the correct halogen.
- Fluorine⇔-219.6°C ✓
- Chlorine⇔-101.5°C ✓
- Bromine⇔-7.3°C ✓
- Iodine⇔113.7°C ✓
- Astatine⇔302.0°C ✓
- Calculate the relative molecular mass of a bromine molecule.
- '160' ✓
- Choose a halogen from the list which would displace chlorine from potassium chloride.
- Bromine
- Fluorine ✓
- Astatine
- Iodine
-
- Select the responses which explain why bromine is more reactive than iodine.
- Iodine is a larger atom than bromine. ✓
- Bromine's outer electron shell is closer to the positively charged nucleus. ✓
- Outer electrons in bromine are more strongly attracted to the nucleus. ✓
- Bromine atoms gain electrons more easily from all other elements.
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Worksheet
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Presentation
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Lesson Details
Key learning points
- Group 7 elements are very reactive and their reactivity decreases down the group.
- Moving down Group 7 elements, atomic mass, density, and melting and boiling points increase.
- In chemical reactions, atoms of Group 7 elements gain one outer electron making just full electron shells.
- Going down Group 7, the force attracting an extra electron reduces with the distance of each shell from the nucleus.
- Halogens are elements, halides are salts.
Common misconception
Pupils often forget that the halogens are diatomic molecules.
Explanation of the bonding to form molecules helps to explain why they exist as diatomic molecules.
Keywords
Salts - are ionic compounds formed from positive and negative ions electrostatically attracted to each other.
Halogens - are reactive non-metallic elements in Group 7 of the periodic table which react with metals to form salts.
Halides - are the name of salts formed from halogens, e.g sodium chloride (NaCl).
Diatomic - element consists of two atoms of the same type, chemically bonded together.
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