Trends in Periodic Properties

The periodic trend of a decrease in atomic radii across a period is readily seen in the Figure 6.4. Other properties related to atomic radii show a similar pattern. Knowing that the elements exhibit a general periodic trend allows us to predict unknown properties for elements and aided in the discovery of unknown elements. The periodic nature of the elements supported the development of the quantum theory. The elements show a periodic pattern in both their properties and electron configurations. The periodic trend in properties of the elements... 

The oxides of main-group elements show periodic trends in properties. Oxides of metals tend to be ionic and to form basic solutions in water. Oxides of nonmetals are molecular and the anhydrides of acids. 

Because we have not studied periodic trends in properties of transition metals, it would be difficult for you to predict that Cu is more active than Ag. The fact that this reaction occurs (see Figure 4-3) shows that it is. 

When the Russian chemist Dmitri Mendeleev (1834-1907) developed his version of the periodic table in 1869, he arranged the elements known at that time in order of atomic mass or atomic weight so that they fell into columns called groups or families consisting of elements with similar chemical and physical properties. By doing so, the rows exhibit periodic trends in properties going from left to right across the table, hence the reference to rows as periods and name periodic table. ... 

Atomic radii, ionization energies, and electron affinities are properties of individual atoms. With the exception of the noble gases, however, none of the elements exist in nature as individual atoms. To get a broader understanding of the properties of elements, we must also examine periodic trends in properties that involve large collections of atoms. 

Periodic trends in properties can be studied with the use of online computer databases. These contain large amounts of data related to atomic, physical and chemical properties. These can be extracted and analysed by a spreadsheet or displayed graphically by the database. Figure 3.30 shows the front page of WebElements (www.webelements.com) developed by Professor Mark Winter at Sheffield University. 

Many of the periodic trends in properties of the elements can be explained using Coulomb s law, which states that the force (F) between two charged objects (Qi and is directly proportional to the product of the two charges and inversely proportional to the distance (d) between the objects squared Force is inversely proportional to d, whereas energy is inversely proportional to d [W Section 5.1]. The SI unit of force is the newton (N = m kg/s ) and the SI unit of energy is the joule (J = m kg/s"). 

Effective Nuclear Charge Periodic Trends in Properties of Elements... 

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