The Periodic Chart

My interest in the periodic table has at least two aspects. Firstly, like so many people before me, I fell in love with the rational beauty of the periodic chart that appears to systematize all the kinds of elementary substances that a student of chemistry would ever encounter.1 The extent to which students are exposed to the periodic table and the stage at which this takes place seems to vary a good deal depending on geographical location and on the era in which they learn chemistry. In my own case it was in London in the 1960s where we were not initially taught the periodic table, although it was displayed on the classroom walls. 

Note, however, that hydroxide is not on the periodic chart. That is because hydroxide is a polyatomic ion. Remember that polyatomic ions always travel together as a unit. The only way to know the charge of a polyatomic ion is to memorize it. Hydroxide has a charge of -1. So, when sodium (with a charge of +1) and a hydroxide come into contact with one another, a sodium atom gives its one valence electron to a hydroxide ion, which needs one... 

Cover design by Nick Krenitsky is representational only and is not intended to reflect a scientifically accurate model of the periodic chart of the elements in the cover design, boldface type at top of square is atomic number, followed by chemical symbol and approximate atomic weight. 

Look at the periodic chart opposite.1 The elements in the same vertical columns have very similar properties. For example, all the elements in Group I are metals that react with water to produce hydrogen. This is because the electrons in all the elements in Group I are arranged around the nucleus in a similar pattern. 

There are several forms in which the elements of the periodic chart may be arranged. The version shown here is one of the forms now in widespread use. Groups I, II, III, etc., and the noble gases are called the Main Group Elements. All of their inner shells are fully occupied with electrons. The other elements are called the Transition Elements. They all have at least one inner shell that is only partially filled with electrons. Referring to the entire table, the numbers written above the symbols of the elements (always whole numbers) are the atomic numbers of the elements, and the numbers written below the symbols of the elements (not necessarily whole numbers) are the atomic weights of the elements. Parentheses indicate insufficient information exists or material is not yet official. 

The six elements in the first column of the periodic chart, excluding hydrogen, make up Group I. They are called the alkali metals. Hydrogen is not a metal, probably because its atom is so small. The others all have a shiny luster, and they conduct electricity and heat well. Any element which has these properties is called a metal. The alkali metals are these ... 

The alchemists of the Middle Ages found that some substances could not be dissolved in water or transformed by fire. They called these substances earths. If the alchemists had known how to break them apart, as chemists can today, they would have found them to be composed of oxygen and the metals from Group II. The six alkaline-earth metals comprising Group II on the periodic chart are ... 

Look at the periodic chart again. Between Groups II and III are a number of elements which do not fall into any of the main groups. They are called transition elements. 

The strangest section of the periodic chart comes in the first transition subgroup. Under scandium and yttrium (marked with stars on the periodic chart) fall two long horizontal lists of elements so much alike that they are squeezed into two squares of the chart. Elements with the atomic numbers 57-71 are called the lanthanides. The actinides are elements with the atomic numbers 89-103, and they are all radioactive. These transition elements are as follows ... 

These elements have all been named for famous scientists or for the places of their creation. For example, americium, berkelium, and californium were named after obvious geographical locations. Nobelium was named for the Nobel Institute, although later study proved it was not really created there. Curium was named for Marie Curie, the discoverer of radium. Einsteinium was named for the famous physicist, Albert Einstein. Fermium and lawrencium were named for Enrico Fermi and Ernest O. Lawrence, who made important discoveries in the field of radioactivity. Mendelevium was named for the discoverer of the periodic chart. 

Called the Iron Triad on the periodic chart, the elements are ... 

These three elements are part of the transition series, but it is easier to group them sideways than with the elements below them on the periodic chart. They are all hard gray metals, with... 

These six metals located beneath the iron triad on the periodic chart are very much alike. The first three are called the light platinum triad. The heavy platinum triad includes the other two and platinum itself. They are usually found together in nature and are used for similar things. All are shiny and beautiful and they do not tarnish or rust. 

Zinc, cadmium, and mercury are the last subgroup of the transition series. Their chemistry is very like that of the alkaline earths of Group II on the periodic chart. 

The position on the periodic chart under lead would be filled by an element of atomic number 114. No such element is yet known, but scientists theorize that this would be a very stable element if it could be found or created, and it might have some very important uses. This much-sought element is referred to as i eka-lead, using the naming system Mendeleyev used for undiscovered elements in the original periodic chart. 

Electricity is carried in metals by free electrons jumping from atom to atom. Metals are good conductors of electricity because their structure allows electrons to move about easily. Most of the elements on the left and center sections of the periodic chart have atoms with electrons held loosely enough to carry electricity. 

The discovery of these gases came as a great surprise to chemists. The periodic chart had predicted a few undiscovered elements, but no one expected a whole new group to be found. 

While many elements can be studied using NMR spectroscopy, only those elements at the top of the periodic chart are commonly measured by soil chemists, and of those, carbon-13 (13C) and phosphorus-31 (31P) are the most frequently investigated. Phosphorus is of particular interest because it is an essential nutrient for both plants and animals. 

Ununtrium is located on the periodic chart in group 13 (IIIA) just below thallium and indium. It is expected to have chemical and physical properties similar to these two homo-logues. Since only one or two unstable atoms of the isotopes of ununtrium have been synthesized, its melting point, boiling point, and density are not known. 

Ahrland s (1973) classification distinguishes incompletely hydrolyzed ions into types a and b. Cations of type a form stable complexes with electronic donors of the first row of the periodic chart through electrostatic interactions those of... 

The term isotope was coined by Soddy (1914) to define two or more substances of different masses occupying the same position in the periodic chart of the elements. Soddy s hypothesis was adopted to explain apparent anomalies in the relative positions of three couples of elements (Ar-K, Co-Ni, and Te-I) in the periodic chart. For instance, potassium is present in nature with three isotopes with masses of 39, 40, and 41, respectively, in the following proportions = 93.26, = 0.01, and = 6.73. Because the pro-... 

The lanthanides have, as known, very similar chemical properties across the series. Writing them in a single separate line in the periodic chart intends to convey this information to the reader. 

Fig. 3. Wigner-Seitz radii of d-transition metals and actinides vs atomic number Z. To the plot, elements displaying empty and full d- and f-shell have been added. In abscissae, the groups of the Periodic Chart of Elements have been indicated (see, e.g. Handbook of Chemistry and Physics). The figure shows the sudden jump in radius between Pu and Am discussed in this chapter, and, more deeply, in Chap. C...

Transitions from a localized to an itinerant state of an unfilled shell are not a special property of actinides they can, for instance, be induced by pressure as they rue in Ce and in other lanthanides or heavy actinides under pressure (see Chap. C). The uniqueness for the actinide metals series lies in the fact that the transition occurs naturally almost as a pure consequence of the increase of the magnetic moment due to unpaired spins, which is maximum at the half-filled shell. The concept has resulted in re-writing the Periodic Chart in such a way as to make the onset of an atomic magnetic moment the ordering rule (see Fig. 1 of Chap. E). Whether the spin-polarisation model is the only way to explain the transition remains an open question. In a very recent article by Harrison an Ander-... 

Basicity of metai oxides. In a given periodic group, basicity of oxides tends to increase as one progresses down the periodic chart (see Table 9.1) For example, in group I1A (2) BeO is amphoteric, but the heavier oxides (MgO,... 

It is generally assumed that the properties of the various families of the periodic chart change smoothly from less metallic (or more electronegative) at the top of the family to more metallic (or less electronegative) at the bottom of the family. Certainly for the extremes of the chart—the alkali metals on the left and the halogens and noble gases on the right—this Is true the ionization potentials, for example, vary in a rather monotonous way. This is not true For certain central parts of the chart, however. 

The common long form of the periodic chart (Fig. 211) may be considered a graphic portrayal of the rules of atomic structure given previously. The arrangement of the atoms follows naturally from the aufbau principle The various groups oT the chart may be classified as follows ... 

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