why magnet attracts only Fe,Ni.Co? why not attract other elements?

Magnets don`t attract only those metals. Magnetism occurs when a large number of electrons with parallel spins occur within a crystal. The atoms of any element which has electrons with parallel spins behave like a magnet..................................................................... Magnetic interaction can be observed in substances which are either **ferromagnetic** or **paramagnetic**. ///Ferromagnetic materials/// are made of many domains - regions where electrons have parallel spins. When magnetic field is applied, all of them arrange as if they form a crystal lattice, themselves...................................................................................... ///Paramagnetic materials///, on the other hand, don`t have an ordered structure in the absence of a magnetic field. When it is applied, though, their electrons align, so that the spin of all their atoms are parallel. You obtain essentially the same picture. Introducing paramagnetic material in a magnetic field, you can magnetize it. When the source of the magnetic field is turned off, entropy takes over and rearranges the spins in a random, chaotic way, just as they were before the outside disturbance....................................... 0........................................................The third category of materials are ///diamagnetics///. Their atoms don`t have electrons with parallel spin, so even in very strong magentic fields, the atoms can`t arrange in a particular way, so they can`t be attracted to magnets.