why are some objects magnetic and others are not ?

Almost all magnetism is caused by electrons.

Individual electrons have an intrinsic magnetic moment.

In an atom, the electron's angular motion around the nucleus also causes a magnetic moment.

Since all solid materials are composed of atoms and include electrons, the question becomes: why aren't all materials magnetic?

Many atoms only have paired electrons, with the intrinsic magnetic moment of each electron cancelled out by the intrinsic magnetic moment of its paired electron.

Many atoms only have "filled sub-shells", which have zero net angular motion.

Atoms with either unpaired electrons, or unfilled sub-shells, or both, are inherently magnetic. However, in many materials, the magnetic moments of these atoms point in random directions, so they cancel out and the bulk material is nonmagnetic.

It is to do with the pairing of electrons and their dipoles. Basically metals with uneven electrons or half shells are magnetic. Three main metals that are Iron, Cobolt and Nickel. With Iron being the main one.

Explanation:

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