Lesson 6 of 6

Predicting from patterns

Goal: Use patterns in the periodic table to make predictions.

Puzzles for this lesson

Word search0 of 8 foundCrossword0 of 38 letters
A grid of coloured tiles with one tile missing, and a magnifying glass beside the gap

The elements in a group follow a pattern. Once you know the pattern, you can predict an element you have never seen.

  • A trend is a pattern in a property. Going down Group 1, the melting points fall. Going down Group 7 and Group 0, the boiling points rise.
  • To estimate a missing value, look at the elements above and below. The missing value usually lies between theirs.
  • Reactions follow patterns too. Group 1 gets more reactive going down. Group 7 gets less reactive going down.
−300−200−1000100200Boiling point in °CGroup 7, going down the group →FClBrI−188 °C−34 °C59 °C184 °C

Chlorine boils at −34 °C and iodine at 184 °C. Bromine lies between them in the group, and so does its boiling point: 59 °C.

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Key words in this lesson

Periodic table A chart of all the elements, arranged in rows and columns

Group A column of the periodic table

Period A row of the periodic table

Reactive Takes part in chemical reactions easily

Trend A pattern in a property as you go down a group or across a period

For teachers: AQA 3.5.3 · Pearson Edexcel 17.4 · Cambridge 9Cm.01 in part, 9Cp.01