Element periodicity

Key words elements periodic table Madelung rule left-step table... 

Palladium is the middle element in group 10 of the transition elements (periods 4, 5, and 6). Many of its properties are similar to nickel located above it and platinum just below it in this group. 

The Noble Gases (Inert Gas Elements) Periods 2 to 6, Group 18 (VIIIA)... 

Lanthanide Series (Rare-Earth Elements) Period 6... 

Chemistry Wed Elements Periodic Table, http //www.webelements.com/webelements/elements/text.html (accessed October 24, 2005). 

Cover images Murray Robertson/visual elements 1998-99, taken from the 109 Visual Elements Periodic Table, available at www.chemsoc.org/viselements... 

Translational symmetry. 74 Translawrencium elements, periodicity of. 615-617 Transport, dioxygen, 895-910 Triatomic molecules and ions, molecular orbitals in, 175-182... 

Each row on the periodic table is called a period. The first period contains hydrogen and helium. The second period begins with lithium and ends with neon. Because each successive element has one additional proton, each successive element also has one additional electron. In fact, most chemists tend to focus on the electrons, rather than the protons as a means of predicting chemical and physical proclivities of the elements. Periods represent adding electrons to quantum energy levels in the atom, which are called electron shells. Atoms at the end of a period each have an electron shell filled to its capacity with electrons. 

One of the benefits that quantum theory has for chemistry is an improved understanding of elemental periodicity, spectroscopy and statistical thermodynamics topics which can be developed without reference to the nature of electrons, atoms or molecules. The success of these applications depend on approximations to model many-electron atoms on the hydrogen solution and the recognition of spin as a further component of electronic angular momentum, subject to the secondary condition known as (Pauli s) exclusion principle. 

Like elemental periodicity, which is a function of electron configuration, an empirical periodic function for nucleons, known as the magic-number pattern, has been derived. The reason why this function has been less successful... 

The second part of the book re-examines the traditional concepts of chemistry against the background of physical theories adapted for chemistry. An alternative theory is formulated from the recognition that the processes of chemistry happen in crowded environments that promote activated states of matter. Compressive activation, modelled by the methods of Hartree-Fock-Slater atomic structure simulation, leads to an understanding of elemental periodicity, the electronegativity function and covalence as a manifestation of space-time structure and the golden ratio. 

In the eight element periods the chemical properties of the elements are dependent on the tendency for the atoms to gain or lose electrons to acquire the structure of the atoms of the inert gases at either end. 

The shorter transition series in the eighteen element periods are indicated in the table by printing the symbols of the elements in heavy type or italics. 

Two other, partially successful models to account for elemental periodicity, were proposed before and forgotten after the advent of quantum theory. An anonymous proposal, later ascribed to Prout, was based on the assumption that all atoms are composites of hydrogen. The purpose of this proposal was to account for the statistically improbable distribution of relative atomic weights, close to integer values. Following the discovery of isotopes Prout s hypothesis gained some new respectability, but it has never been fully exploited. Another theory was summarized by its author [20] in the statement ... 

Each of the three theories accounts for some, but not all aspects of elemental periodicity. The common ground among the three may well reveal the suspected link with space-time structure. What is required is to combine aspects of the wave-mechanical model of hydrogen, the structure of atomic nuclei and number theory. 

Figure 2.4 Diagram to identify elemental periodicity in four special forms...

Figure 2.15 Simulation of elemental periodicity by a sine curve. The periodic part occurs between atomic numbers 3 and 99...

Earlier speculations about the effect of the curvature of space on elemental synthesis and the stability of nuclides (2.4.1) are consistent with the interface model. The absolute curvature of the closed double cover of projective space, and the Hubble radius of the universe, together define the golden mean as a universal shape factor [233], characteristic of intergalactic space. This factor regulates the proton neutron ratio of stable nuclides and the detail of elemental periodicity. The self-similarity between material structures at different levels of size, such as elementary particles, atomic nuclei, chemical... 

Porous ceramic or micrometallic filters are very effective for recovering entrained fines from gas streams (228,252). Multiple installations are required because it is necessary to blow back each filter element periodically to dislodge the catalyst cake that builds up on the surface and leads to increased pressure drop. Filters have been used for catalyst recovery in other fluid-catalyst processes where high cost or other considerations justify extraordinary measures to minimize catalyst losses. However, this expedient has not been employed in commercial fluid cracking units because losses are readily controlled to a reasonable level by simpler means. In fact, intentional discard of catalyst is often practiced, in addition to normal losses, in order to maintain catalyst quality at a high level by permitting increased additions of fresh catalyst. 

Thus, the s-, p-, d-, and f-blocks determine the shape of the periodic table. As you proceed down through the periods, the principal energy level increases, as does the number of energy sublevels containing electrons. Period 1 contains only s-block elements, periods 2 and 3 contain both s- and p-block elements, periods 4 and 5 contain s-, p-, and d-block elements, and periods 6 and 7 contain s-, p-, d-, and f-block elements. 

---