4CH1

Group 1: The Alkali Metals

Inorganic Chemistry · 1 question type

Practise

Exam Frequency Analysis

Past paper frequency (2018 to 2024)

This topic accounts for approximately 5% of your exam marks.

stable
Rare
Stable5%

Reactions with water and trends in reactivity down the group are standard exam fare.

What Group 1 is

  • Group 1 is the leftmost vertical group on the periodic table
  • Its elements are the alkali metals: lithium, sodium, potassium, rubidium, caesium and francium
  • They are called the alkali metals because they react with water to form alkaline solutions (pH > 7)
  • Each atom has one electron in its outermost shell, which is why all six elements share a family resemblance in their chemistry
Periodic table with the Group 1 alkali metals lithium, sodium, potassium, rubidium, caesium and francium highlighted in the leftmost column
Source: Group 1 reactivity & trends by Save My Exams

Physical properties shared by all Group 1 metals

  • All six are soft enough to be cut with a knife
  • A freshly cut surface is shiny and silvery
  • They have relatively low densities — the top three (Li, Na, K) actually float on water
  • They have low melting points compared with most other metals
  • They are stored under oil to keep them away from air and moisture

General reaction with water

  • Every Group 1 metal reacts with cold water to give the corresponding and hydrogen gas

2 M(s) + 2 H2O(l) → 2 MOH(aq) + H2(g)

  • The hydroxide dissolves to give a colourless alkaline solution (lithium hydroxide, sodium hydroxide, potassium hydroxide and so on)
  • The hydrogen gas can be tested by holding a lit splint over the bubbles — it gives the characteristic squeaky pop