With any grouping as loose as is the grouping of 'non-metals', it is inevitable that very different elements will be considered in close proximity - and whatever similarities the periodic table alerts us to, every element remains unique - but it is possible to discern some common uses among the members of this division.
What is most striking, perhaps, is how many of them are essential to life: carbon, nitrogen, oxygen, phosphorus, sulphur. Accordingly, they fulfil life-sustaining roles: phosphorus and nitrogen are used in fertilizers to provide plants with the nitrates and phosphates necessary for growth; oxygen is used to provide the artificial atmospheres which allow divers and astronauts to breathe, and is also employed as an aid to revival for hospital patients.
The division between metals and non-metals is not a clear one, and those elements that exist on the borderline between the two classifications tend to possess properties mid-way between the two. Whereas most non-metals are insulators, metalloids such as arsenic and silicon are semiconductors, and are used widely as such in the electronics industry.
