The magnetic properties of materials are also related to the behaviour of electrons in atoms. An electron in orbit can be thought of as a miniature loop of electric current. According to the laws of electromagnetism, such a loop will create a magnetic field. Each electron in orbit around a nucleus produces its own magnetic field, and the sum of these fields, together with the intrinsic fields of the electrons and the nucleus, determines the magnetic field of the atom. Unless all of these fields cancel out, the atom can be thought of as a tiny magnet.
In most materials these atomic magnets point in random directions, so that the material itself is not magnetic. In some cases—for instance, when randomly oriented atomic magnets are placed in a strong external magnetic field—they line up, strengthening the external field in the process. This phenomenon is known as paramagnetism. In a few metals, such as iron, the interatomic forces are such that the atomic magnets line up over regions a few thousand atoms across. These regions are called domains. In normal iron the domains are oriented randomly, so the material is not magnetic. If iron is put in a strong magnetic field, however, the domains will line up, and they will stay lined up even after the external field is removed. As a result, the piece of iron will acquire a strong magnetic field. This phenomenon is known as ferromagnetism. Permanent magnets are made in this way.
Shell-atomic-model-In-the-shell-atomic-model-electrons-occupyShell atomic model[Credits : Encyclopædia Britannica, Inc.]
Millikan-oil-drop-experiment-Between-1909-and-1910-the-AmericanMillikan oil-drop experiment[Credits : Encyclopædia Britannica, Inc.]
The-Bohr-atom-The-electron-travels-in-circular-orbits-aroundThe Bohr atom[Credits : Encyclopædia Britannica, Inc.]
Atomic-orbitals-Electrons-fill-in-shell-and-subshell-levels-inAtomic orbitals[Credits : Encyclopædia Britannica, Inc.]
Periodic-table-of-the-elements-showing-the-valence-shellsPeriodic table of the elements showing the valence shells.[Credits : Encyclopædia Britannica, Inc.]
Ionic-bond-An-atom-of-sodium-donates-one-of-itsIonic bond[Credits : Encyclopædia Britannica, Inc.]
Polar-covalent-bond-In-polar-covalent-bonds-such-as-thatPolar covalent bond[Credits : Encyclopædia Britannica, Inc.]
Nuclear-binding-energies-shown-as-a-function-of-atomic-massNuclear binding energies, shown as a function of atomic mass number.[Credits : Encyclopædia Britannica, Inc.]
Atomic model of electron configurations.[Credits : Encyclopædia Britannica, Inc.]
Atoms combine to form molecules by transferring electrons, which results in the formation of …[Credits : Acquired from Vast Video]
Learn about atoms, the building blocks of everything on earth.[Credits : Acquired from Vast Video]
Scientists discovered that great amounts of energy could be derived from uranium atoms because of …[Credits : Acquired from Vast Video]
Link to this article and share the full text with the readers of your Web site or blog-post.
If you think a reference to this article on "atom" will enhance your Web site,
blog-post, or any other web-content, then feel free to link to this article,
and your readers will gain full access to the full article, even if they do not subscribe to our service.
You may want to use the HTML code fragment provided below.
We welcome your comments. Any revisions or updates suggested for this article will be reviewed by our editorial staff. Contact us here.
Regular users of Britannica may notice that this comments feature is less robust than in the past. This is only temporary, while we make the transition to a dramatically new and richer site. The functionality of the system will be restored soon.