Group 1 Elements - The Alkali Metals
Known as the ALKALI METALS, Group 1 elements are highly REACTIVE and are considered SOFT METALS with LOW DENSITY.
They all possess ONE ELECTRON in their OUTER SHELL, contributing to their reactivity and similar properties.
Reactivity of Alkali Metals
- The reactivity of these metals INCREASES as you go down the group. This is because the outer electron is more easily lost due to the INCREASING DISTANCE from the nucleus and a WEAKER ATTRACTION.
- They have LOWER MELTING AND BOILING POINTS and a HIGHER RELATIVE ATOMIC MASS as you move down the group.
- When they react, group 1 elements tend to form IONIC COMPOUNDS with non-metals, usually resulting in white solids that dissolve in water to create colourless ALKALI solutions- hence the name ALKALI METALS.
Reaction with Water
- When reacted with water, alkali metals produce Hydrogen gas and react VIGOROUSLY.
- The reactions become MORE VIOLENT reactions FURTHER DOWN the group.
- They also form HYDROXIDES that are alkaline when dissolved in water.
- Here’s an example for POTASSIUM:
These are the OBSERVATIONS you would see for the first three ALKALI METALS:
Reaction with Chlorine
- Group 1 metals react with Chlorine to form METAL CHLORIDES, which are WHITE SALTS.
- The reactions become more VIGOROUS down the group.
- Here’s the reaction with SODIUM:
Reacting with Oxygen
- The alkali metals react with Oxygen in the air forming METAL OXIDES, which is why the alkali metals TARNISH when exposed to the air.
- The metal oxide produced is a dull coating which covers the surface of the metal.
- Here’s the reaction with LITHIUM:
