Lesson 5 of 6

Group 7 and Group 0

Goal: Describe the halogens and the noble gases.

Puzzles for this lesson

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Group 7 and Group 0 are next to each other in the table, but they behave in opposite ways.

A stoppered flask full of pale yellow-green chlorine gas
Group 7: the halogens. Fluorine, chlorine, bromine and iodine are reactive, coloured, poisonous non-metals.
Three glass tubes glowing orange-red, violet and blue in a dark room
Group 0: the noble gases. Helium, neon and argon are colourless gases that hardly ever react. They glow when electricity passes through them.
  • Halogens react with metals to make salts. Sodium and chlorine make sodium chloride, which is table salt.
  • Halogens get less reactive as you go down the group. This is the opposite of Group 1.
  • Noble gases are inert, which means unreactive. Their atoms hardly ever join up with other atoms: they stay as single atoms. That makes them safe to use in balloons (helium) and to fill light bulbs (argon).

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Key words in this lesson

Group A column of the periodic table

Metal An element that is usually shiny and a good conductor

Non-metal An element that is usually dull and a poor conductor

Halogens The reactive non-metals in Group 7

Noble gases The unreactive gases in Group 0

Reactive Takes part in chemical reactions easily

Inert Unreactive: it hardly ever takes part in a reaction

For teachers: AQA 3.5.3 · Cambridge 8Cc.06 in part