Group 1 (AQA GCSE Chemistry Combined Science): Revision Notes

Group 1

Group 1 elements are known as alkali metals. These are reactive metals that share similar properties and show clear patterns as you move down the group.

Properties of alkali metals

Alkali metals share several key characteristics that make them unique among the elements:

Physical properties:

• They are metals with a shiny appearance
• Low density - the first three elements (lithium, sodium, potassium) are less dense than water, so they float
• Melting and boiling points decrease as you go down the group

Chemical properties:

• Form ions with a +1 charge when they react
• React vigorously with water to produce hydroxides and hydrogen gas
• React with oxygen to form white, solid ionic oxides
• React with chlorine to form white, solid, soluble ionic chlorides

The reactivity pattern

Understanding the reactivity pattern is crucial for predicting how Group 1 elements will behave in chemical reactions.

Why does this happen?

All Group 1 elements have one electron in their outer shell. This outer electron is easily lost during reactions, forming a +1 ion.

As you move down the group:

• The outer electron gets further away from the nucleus
• This makes it easier to lose the outer electron
• Therefore, the elements become more reactive

Reactions with water

All alkali metals react with water following the same general pattern, but with increasing vigour as you go down the group.

General equation: $\text{metal} + \text{water} \rightarrow \text{metal hydroxide} + \text{hydrogen}$

What you observe:

• The metal moves around on the water surface
• Hydrogen gas is produced (you can see bubbles)
• The solution becomes alkaline due to the hydroxide formed
• More reactive metals (like potassium) react more vigorously

Examples of reactions