Artwork showing the electron clouds,or orbitals,of atoms of hydrogen (top),carbon (top left),silicon (top right),iron (centre left),silver (centre right),& europium (bottom). As the number of electrons increases,additional orbitals are filled according to a regular pattern of spherical 's' orbitals (white to blue),dumbbell-shaped 'p' orbitals (orange),'d' orbitals (yellow-green) shaped like crossed dumbbells,& 'f' orbitals (purple). 'S' orbitals can contain up to 2 electrons,'p' orbitals up to 6,'d' orbitals up to 10,& 'f' orbitals up to 14. The extent to which an element's electrons fill these orbitals determines its chemical characteristics |