Use electron arrangements to find elements, then practise Group 1, Group 7 and Group 0 trends. Choose AQA or Edexcel to see the details required for your course.
Atomic number counts protons. A neutral atom has the same number of electrons. Period numbers show how many electron shells are occupied; elements in a group have similar outer-electron arrangements.
Group 1 alkali metals get more reactive going down the group because the outer electron becomes easier to lose. Group 7 halogens get less reactive going down the group because it becomes harder to attract an extra electron. Noble gases in Group 0 have complete outer shells; helium has two electrons in its only shell.
AQA 8462 covers the development of the table and the reactions of the first three alkali metals with oxygen, chlorine and water. Edexcel 1CH0 includes the colours and states of the pure halogens and uses of noble gases. Both assess chemical reasoning and periodic trends.
A simplified table showing Groups 1–7 and 0. On a narrow screen, scroll the table sideways to see Groups 7 and 0. Select an element to see its atomic number, electron arrangement, group and period. Hydrogen is in Group 1 but is not an alkali metal.
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