These are all very reactive metals, forming compounds with almost all of the non-metals. The alkali metals are hazardous substances and are stored under inert (unreactive) oils.
When these metals are freshly cut (exposed to the air), they quickly become coated with corrosion products.
Alkali metals are kept in oil because:
- Prevents contact with O2 so the metal does not corrode.
- Prevents contact with water and moisture in the air.
The transition metals:
These metals, found in the centre of the periodic table, have high melting points. Their compounds are usually coloured e.g. blonde hair contains titanium compounds, brown hair has iron compounds. They are very useful metals from buildings to hip replacements. Some are catalysts.
A catalyst is a chemical that speeds up a reaction without being changed itself e.g. enzymes. Iron is a catalyst for making ammonia.
Group 7: The Halogens:
These are all typical non-metals and fairly reactive forming compounds with most other elements. The Halogens are hazardous substances and are treated with great care – usually in a fume cupboard. The name Halogen means ‘salt-maker’.
The halogens exist as diatomic molecules, this means 2 atoms joined together.
The Noble Gases:
The noble gases are a family of elements at the extreme right hand side of the periodic table. This whole group of elements is very unreactive and exist as single atoms (monatomic).
All the noble gases have boiling points well below room temperature. So they are all gases. They are all found in the atmosphere – i.e. in the air – and all extracted from the air.
Uses:
- Helium – balloons, airships, heliox (oxygen and helium mixture) for deep sea diving.
- Neon – strip lights coloured).
- Argon – light bulbs
- Krypton – lighthouse bulbs.
- Xenon – strobe lights.
