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Auralith Learning

Year 8 · Science · Elements, compounds and the periodic table · Lesson 4

Groups 1, 7 and 0

The properties and trends of the alkali metals, the halogens and the noble gases, including reactions with water and displacement.

Whiteboard video lesson: Groups 1, 7 and 0

25-minute video lesson

Teaching, worked examples and 20 practice questions solved step by step.

Watch free for a month

What your child will learn

  • Describe the properties of group 1 metals
  • Write word equations for group 1 metals with water
  • Describe trends in group 7
  • Predict halogen displacement reactions
  • Explain why noble gases are unreactive and give their uses

The method

  1. Group 1 metal + water makes a metal hydroxide + hydrogen; reactivity increases down the group.
  2. Group 7 halogens get darker and less reactive down the group.
  3. A more reactive halogen displaces a less reactive one from its compound.
  4. Group 0 noble gases are unreactive and made of single atoms.

Key words: alkali metal, halogen, noble gas, reactivity, trend, displacement, hydroxide.

Worked examples

The first three practice questions from the lesson, with every step.

Question 1

Write the word equation for lithium reacting with water.

  1. Step 1: lithium + water
  2. Step 2: → lithium hydroxide + hydrogen

Answer: lithium + water → lithium hydroxide + hydrogen

Question 2

Write the word equation for potassium reacting with water.

  1. Step 1: potassium + water
  2. Step 2: → potassium hydroxide + hydrogen

Answer: potassium + water → potassium hydroxide + hydrogen

Question 3

When sodium reacts with water, a gas is made. Name the gas and how you could test for it.

  1. Step 1: Gas: hydrogen
  2. Step 2: Test: lit splint → squeaky pop

Answer: Hydrogen; it gives a squeaky pop with a lit splint