Metals and Non-metals
Metals and non-metals
Tell metals from non-metals by malleability, ductility, sonority and conduction, say what rusting and corrosion need, and give the nature of a metal oxide and a non-metal oxide.
An ironsmith heats a block of iron until it glows red, then beats it with a hammer until it is an axe. Try the same hammer on a lump of coal and it does not flatten — it shatters. That difference is not about how hard you hit. It is a property of the material, and this chapter is a list of four such properties that sort the world's substances into two families.
The four properties, by name
Malleability: it can be beaten into thin sheets. Ductility: it can be drawn into wires. Sonority: it rings when struck. Conduction: heat and electricity pass through it easily. Metals generally have the four; non-metals generally have none of them, and are soft and dull besides.
Where the tidy rule bends
Sodium and potassium are metals soft enough to cut with a knife, and mercury is a metal that is liquid at room temperature. The four properties describe how metals generally behave, not a test each one has to pass. Plastic, glass, wood, rubber and paper sit outside the two families altogether: they are not elements, so neither name applies to them.
Worked example
Three iron nails are set up for eight days. A: sealed in dry air. B: under boiled water, sealed under a layer of oil. C: half in water, bottle left open. C alone grows a brown deposit. What does that show?
Read bottle A. Air, but no water — and the nail stays clean.
So air by itself is not enough to make the deposit. One suspect is cleared.
Try it together
Work out the nature of two oxides, one from each family.
Each step takes one word: acidic, basic or neutral.
1.A magnesium ribbon is burned in air and leaves a white powder. Stirred into warm water, it turns red litmus blue. What is that solution?
Have a go
Have a go on your own. Sodium is kept under kerosene rather than on a shelf, because of how fiercely it reacts with two things in the open air. Name one of them.
Ready to practise?
Eight questions on what you have just read. Nothing is timed, and you can play as many times as you like.