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The Periodic Table
Quick questions on Group I and Group VII explained: O-Level Chemistry
6short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What are halogen displacement reactions?Show answer
Because reactivity decreases down Group VII, a more reactive halogen displaces a less reactive halogen from a solution of its salt (a halide). For example, chlorine displaces bromine from potassium bromide:
What is reactivity increases down the group?Show answer
Going down, atoms have more electron shells, so the single outer electron is further from the nucleus and held less strongly. Because these metals react by losing that outer electron, it being lost more easily makes them more reactive: potassium reacts more violently with water than sodium, which reacts more than lithium.
What is reactivity decreases down the group?Show answer
Going down, the outer shell is further from the nucleus, so the atom attracts an incoming electron less strongly. Because halogens react by gaining an electron, gaining it less easily makes them less reactive: chlorine is more reactive than bromine, which is more reactive than iodine.
What is q1?Show answer
State the charge of the ion formed by a Group I metal and by a Group VII element. [1 mark]
What is q2?Show answer
Explain why potassium is more reactive than lithium. [2 marks]
What is q3?Show answer
State what is observed when chlorine water is added to potassium iodide solution, and name the reaction type. [2 marks]
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