Johnny Agnoletti, age 10, of Farmington, Ill 

What makes iron rust?

The story of rust is an everyday story of atoms and molecules  The world and everything in it, we are told, is made from about 100 different elements and each element is made of atoms, all of one sort, Iron is an element made from iron atoms, Oxygen is an element made from atoms of oxygen  But when we look around we seep not merely 100 different elements, but countless thousands of different substances  Most of these substances are compounds of assorted elements in which atoms are tied up in little bundles called molecules  A speck of flaky red rust is made from molecules of iron atoms arid oxygen atoms 

A compound of this sort is usually very, very different from its parent elements  Rust is very different from the metal iron and the gaseous oxygen from which it is made  Mater also is a compound containing oxygen and moisture is necessary for the rusting recipe to begin  There is invisible moisture in the airy even over the driest deserts  Of course, there is more moisture in the air on a foggy, humid or rainy day  This is why iron rusts faster in a damp climate or when buried in the damp ground,

The rusting recipe is called oxidation, which means that it urea oxygen  Fire also is called oxidation because it too is a chemical process using oxygen„ The process by which your body turns food into energy also uses up oxygen and it too is called oxidation  You can see then that the burning process is not always a fast flaming fire  There are fast and slow forms of oxidation, slow burning and fast burning 

Rusting is one of the slow burning processes  It begins when iron comes in contact with moist air  Iron tends to be cooler than the air around it and this causes the moisture in the air to gel into the finest of misty droplets 

The droplets :form a film on the iron and the rusting recipe begins  In the first stage, the moisture takes on a greenish tinge  Then a few atoms of iron and oxygen combine with each other to form molecules,

Each of these molecules is a particle of the compound called iron oxide, which is the chemical name for plain old rust, In time, enough molecules form to turn some of the hard iron into soft red flakes of rust  The surface of the iron is now rough and more water can collect 3n the tiny pockets between the flakes  The rusting recipe goes faster  This is why 3t is sensible to stop rust before it begins  'rye cover steel bridges and outdoor girders with paint which seals out the moisture  We take iron garden tools indoors and maybe coat them with grease to keep them dry 

 Rust, strange to say, has  its good points  For it turns the metal iron in the soil into iron oxide  All plants and animals need iron, but they can only use it in the form of the compound iron oxide  Our bodies need iron to make rich red blood  Ws get our best supply of iron by eating green plants which have taken up iron oxide from the soil