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However, because lanthanum (which does not fill the 4 f orbital) exhibits similar properties, it is usually included with the lanthanides. The lanthanides can be defined as those metals that fill the 4 f orbital. The 'missing' metals -lanthanides and actinides, respectively -are shown at the bottom of the chart. In most versions of the periodic table, lanthanum (57) is followed by hafnium (72) in the transition metals section of the chart similarly, actinium (89) is followed by rutherfordium (104). Thus these two families are listed by themselves. The lanthanides and actinides are further set apart even from the transition metals, due to the fact that these elements also fill the highly complex f orbitals. In addition, they are the only elements that have valence electrons on two different principal energy levels. It is important only to know that, unlike the representative elements, transition metals fill the sublevel corresponding to the d orbitals. The four basic types of orbital patterns are discussed in the Transition Metals essay, and will not be presented in any detail here. Means that if you could take millions of photographs of the electron during a period of a few seconds, the resulting blur of images would describe more or less the shape of a specified orbital. Orbital patterns loosely define the overall shape of the electron cloud, but this does not necessarily define the paths along which the electrons move. The higher the energy level, the larger the number of possible orbital patterns, and the more complex the patterns. (Note that period number and principal energy level number are the same.) In the seventh principal energy level, there are seven possible sublevels. The actinides, which would be on Period 7 if they were included on the periodic table with the other transition metals, have seven principal energy levels. The pattern of orbitals is determined by the principal energy level of the atom, which indicates a distance that an electron may move away from the nucleus.Įach principal energy level is divided into sublevels corresponding to the number n of the principal energy level. Together with the core electrons, which are at lower energy levels, valence electrons move in areas of probability referred to as orbitals. The transition metals are distinguished by their configuration of valence electrons, or the outer-shell electrons involved in chemical bonding. ORBITAL PATTERNS OF THE TRANSITION METALS. Here these specifics will be discussed only briefly. The reader is encouraged to consult that essay, as well as the one on Families of Elements, which further places the transition metals within the larger context of the periodic table. The qualities that distinguish the transition metals from the representative or main-group elements on the periodic table are explained in depth within the Transition Metals essay. Actinides and lanthanides are referred to as inner transition metals, because, although they belong to this larger family, they are usually considered separately -rather like grown children who have married and started families of their own. Why are actinides and lanthanides set apart from the periodic table? This can best be explained by reference to the transition metals and their characteristics. Then there is uranium, 'star' of the actinide series: for centuries it seemed virtually useless then, in a matter of years, it became the most talked-about element on Earth. Likewise several of the naturally occurring actinides are used in areas ranging from medical imaging to powering spacecraft. Few of these elements have important applications in daily life on the other hand, some of the lower-number transuranium elements do have specialized uses. These 10 are classified, along with the nine elements to the right of actinium on Period 7 of the periodic table, as transuranium (beyond uranium) elements. Only four of them occur in nature, while the other 10 have been produced in laboratories. But there is more that distinguishes the actinides, a group of 14 elements along with the transition metal actinium. Both of these families exhibit unusual atomic characteristics, properties that set them apart from the normal sequence on the periodic table.

The actinides (sometimes called actinoids) occupy the 'bottom line' of the periodic table -a row of elements normally separated from the others, placed at the foot of the chart along with the lanthanides.

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