Group 7 (Edexcel GCSE Combined Science: Chemistry): Flashcards
Exam code: 1SC0
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- FrontGroup 7 (Halogens)
Name Group 7 of the Periodic Table.
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Name Group 7 of the Periodic Table.
Group 7 of the Periodic Table is called the halogens.
Explain why fluorine is in Group 7 of the Periodic Table.
Fluorine is in Group 7 of the Periodic Table because it has 7 electrons in its outer shell.
Define halogen.
The halogens are the non-metal elements in Group 7 of the periodic table. They exist as diatomic molecules and form ionic compounds with metals and covalent compounds with non-metals.
State the formula of a chlorine molecule.
The formula of a chlorine molecule is Cl2.
True or False?
The halogens become less reactive going down Group 7.
True.
The halogens become less reactive going down Group 7 because atoms have more electron shells, so an incoming electron is held less strongly by the nucleus and is harder to gain.
Give the colour and state of chlorine at room temperature.
The colour and state of chlorine at room temperature is a green gas.
Explain why chlorine has a higher melting point than fluorine.
Chlorine has a higher melting point than fluorine because there are stronger intermolecular forces which need more energy to overcome.
Describe the test and result for chlorine gas.
The test and result for chlorine gas is using damp blue litmus paper and it bleaches white.
The halogens all have .......... electrons in their outer shell, which means they tend to gain one electron to form ions with a .......... charge.
The halogens all have seven electrons in their outer shell, which means they tend to gain one electron to form ions with a 1− charge.
Give the colour and state of bromine at room temperature.
The colour and state of bromine at room temperature is an orange-brown liquid.
Give the colour and state of iodine at room temperature.
The colour and state of iodine at room temperature is a grey solid.
Describe what happens to the melting points of the halogens going down the group.
Going down the group, melting points of the halogens increases.
What is meant by a halogen displacement reaction?
A halogen displacement reaction is one where a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide.
Write the word equation for the displacement reaction between potassium bromide and chlorine.
The word equation for the displacement reaction between potassium bromide and chlorine is:
potassium bromide + chlorine → potassium chloride + bromine
Write the balanced symbol equation for the reaction between potassium iodide and bromine.
The balanced symbol equation for the reaction between potassium iodide and bromine is:
Br2 + 2KI → 2KBr + I2
Explain why iodine cannot displace chlorine from potassium chloride.
Iodine cannot displace chlorine from potassium chloride because iodine is less reactive than chlorine.
When chlorine displaces bromine from potassium bromide, what colour will the solution turn?
The solution will turn orange.
True or False?
The halogens react with metals to form covalent compounds.
False.
The halogens react with metals to form ionic compounds.
Give the charge of the halide ions formed when halogens react with Group 1 metals.
The charge of the ions formed when halogens react with Group 1 metals is 1−.
True or False?
Hydrogen halides dissolve in water to form acidic solutions.
True.
Hydrogen halides dissolve in water to form acidic solutions.
Name the compound formed when hydrogen reacts with chlorine.
The compound formed when hydrogen reacts with chlorine is hydrogen chloride.
Define halide ion.
A halide ion is a negatively charged ion formed when a halogen atom gains one electron, giving it a charge of 1− (e.g. Cl⁻, Br⁻, I⁻).
What type of structure do hydrogen halides have?
Hydrogen halides have simple molecular structures.
When halogens react with metals, they form .......... compounds; when they react with non-metals, they form .......... compounds.
When halogens react with metals, they form ionic compounds; when they react with non-metals, they form covalent compounds.
Define the term oxidation.
Oxidation is the loss of electrons.
True or False?
In the following reaction, chlorine is reduced:
Cl2 + 2KI ⟶ 2KCl + I2
True.
Chlorine is reduced because it gains electrons.
Define the term reduction.
Reduction is the gain of electrons.
True or False?
In the following reaction, potassium ions are oxidised:
Cl2 + 2KI ⟶ 2KCl + I2
False.
Iodide ions are oxidised as each one loses an electron.
What is meant by a redox reaction?
Redox reactions are ones where oxidation and reduction occur simultaneously.
In the reaction Cl2 + 2KI ⟶ 2KCl + I2, iodide ions are .......... because they .......... electrons to form iodine molecules.
In the reaction Cl2 + 2KI ⟶ 2KCl + I2, iodide ions are oxidised because they lose electrons to form iodine molecules.
Define the term reactivity.
Reactivity is the tendency of a substance to undergo a chemical reaction by losing or gaining electrons.
What are halide ions?
Halide ions are ions formed when halogen atoms gain an electron, carrying a 1− charge.
True or False?
It becomes easier for halogen atoms to gain electrons as you go down the group.
False.
It becomes harder for halogen atoms to gain electrons as you go down the group, making them less reactive.
Describe the trend in reactivity of the halogens going down the group.
The trend in reactivity of the halogens is that, going down the group, reactivity decreases.
Give the electronic configuration of a chlorine atom.
The electronic configuration of a chlorine atom is 2.8.7.
Reactivity .......... going down Group 7 because the atoms have more electron shells, making it harder for the nucleus to attract an incoming .......... .
Reactivity decreases going down Group 7 because the atoms have more electron shells, making it harder for the nucleus to attract an incoming electron.
Why is fluorine the most reactive halogen?
Fluorine is the most reactive halogen because it has the fewest shells so it is easier for the nucleus to attract an electron.
Explain why reactivity decreases going down Group 7.
Reactivity decreases going down Group 7 because the atoms have more shells, meaning there is less attraction between an incoming electron and the positive nucleus making it harder to gain an electron.
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