Group trendsIB MYP Sciences: Flashcards
Card 1 of 140 of 14 known
Question
Which gas is produced when an alkali metal reacts with water?
Tap or press Space to reveal
Tap card or press Space to flip
See all 14 cards
- Which gas is produced when an alkali metal reacts with water?
- Hydrogen.
- What else forms when an alkali metal reacts with water?
- A metal hydroxide, which makes an alkaline solution.
- What is the trend in reactivity down Group 1?
- Reactivity increases.
- Why are the alkali metals stored under oil?
- To keep them away from oxygen and water vapour in the air.
- Give a use of lithium.
- Rechargeable batteries.
- What is the trend in reactivity down Group 7?
- Reactivity decreases.
- What is the colour and state of chlorine at room temperature?
- Yellow-green gas.
- What is the colour and state of bromine at room temperature?
- Red-brown liquid.
- What is the colour and state of iodine at room temperature?
- Grey-black solid.
- How does the melting point change down Group 7?
- It increases.
- What happens when chlorine is added to potassium bromide solution?
- Chlorine displaces bromine, forming potassium chloride and orange bromine.
- Why are the noble gases unreactive?
- They have a full outer shell of electrons.
- Give a use of helium and a use of argon.
- Helium for balloons and airships; argon in filament lamps or for welding.
- What flame colour does potassium burn with in water?
- Lilac.
Exam questions on Group trends
- A technician in Cape Town is preparing a demonstration of the alkali metals. She will drop small pieces of lithium, sodium and potassium into separate troughs of water. Before the lesson, she keeps the three metals in bottles of oil.Describe what the technician would see when a small piece of potassium is added to water, and how this differs from lithium.2 marks
- A chemistry class in Nairobi is investigating the halogens in Group 7. The teacher has sealed samples of chlorine, bromine and iodine, and solutions of potassium chloride, potassium bromide and potassium iodide. In one test she adds chlorine water to potassium bromide solution, and the colourless solution turns orange.Explain why the solution of potassium bromide turns orange when chlorine water is added.2 marks
- A student investigates how reactive lithium, sodium and potassium are with water. For each metal she puts 100 cm³ of water in a trough, adds a piece of the metal of mass 0.10 g, and records the time taken for the metal to disappear. She predicts that reactivity increases down Group 1. Her results: lithium 120 s, sodium 45 s, potassium 8 s.Identify the independent variable and the dependent variable in the investigation, and suggest one safety precaution.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).