Periodic table property trends

An approximate type of consistency relates to trends in properties within families in the periodic table. Expected trends can aid both in estimation of missing data and in evaluation of observed data, for example, in a series from fluoride to iodide or from polyhalide to monohalide. 

The arrangement of the periodic table reveals trends in the properties of the elements. A trend is a predictable change in a particular direction. For example, there is a trend in the reactivity of the alkali metals as you move down Group 1. As Figure 15 illustrates, each of the alkali metals reacts with water. However, the reactivity of the alkali metals varies. At the top of Group 1, lithium is the least reactive, sodium is more reactive, and potassium is still more reactive. In other words, there is a trend toward greater reactivity as you move down the alkali metals in Group 1. 

Related topicsThe periodic table (A4) Trends in atomic properties (A5)... 

Although atomic theory and electron configuration help us understand the arrangement and behavior of the elements, it s important to remember that the design of the periodic table is based on observing properties of the elements. Before we use the concept of atomic structure to explain how and why atoms combine to form compounds, we need to understand the characteristic properties of the elements and the trends that occur in these properties on the periodic table. These trends allow us to use the periodic table to accurately predict properties and reactions of a wide variety of substances. 

Chemical and physical properties of elements follow trends within the periodic table. These trends are described in terms of changes in properties of elements from the top to the bottom of groups, and from the left to the right of periods. The sizes of atoms and first ionization energies are two properties that show distinct trends. 

Modern periodic table including trends in periodic properties Modern concepts of chemical bonding Modern coordination theory... 

In any group of the periodic table we have already noted that the number of electrons in the outermost shell is the same for each element and the ionisation energy falls as the group is descended. This immediately predicts two likely properties of the elements in a group (a) their general similarity and (b) the trend towards metallic behaviour as the group is descended. We shall see that these predicted properties are borne out when we study the individual groups. 

The trends in chemical and physical properties of the elements described beautifully in the periodic table and the ability of early spectroscopists to fit atomic line spectra by simple mathematical formulas and to interpret atomic electronic states in terms of empirical quantum numbers provide compelling evidence that some relatively simple framework must exist for understanding the electronic structures of all atoms. The great predictive power of the concept of atomic valence further suggests that molecular electronic structure should be understandable in terms of those of the constituent atoms. 

In addition to the prediction of new elements and their probable properties, the periodic table has proved invaluable in suggesting fruitful lines of research in the preparation of new compounds. Indeed, this mode of thinking is now so ingrained in the minds of chemists that they rarely pause to reflect how extraordinarily difficult their task would be if periodic trends were unknown. It is the ability to anticipate the effect of changing an element or a group in a compound which enables work to be planned effectively, though the prudent chemist is always alert to the possibility of... 

The simple trend in the formulas shown by the third-row elements demonstrates the importance of the inert gas electron populations. The usefulness of the regularities is evident. Merely from the positions of two atoms in the periodic table, it is possible to predict the most likely empirical and molecular formulas. In Chapters 16 and 17 we shall see that the properties of a substance can often be predicted from its molecular formula. Thus, we shall use the periodic table continuously throughout the course as an aid in correlating and in predicting the properties of substances. 

In the preceding chapter we looked at the elements of the third row in the periodic table to see what systematic changes occur in properties when electrons are added to the outer orbitals of the atom. We saw that there was a decided trend from metallic behavior to nonmetallic, from base-forming to acid-forming, from simple ionic compounds to simple molecular compounds. These trends are conveniently discussed... 

There are similar, but smaller, trends in the properties of elements in a column (a family) of the periodic table. Though the elements in a family display similar chemistry, there are important and interesting differences as well. Many of these differences are explainable in terms of atomic size. 

We see that, no matter what type of bonding situation is considered, there is a trend in size moving downward in the periodic table. The alkaline earth atoms become larger in the sequence Be < Mg < Ca < Sr < Ba. These atomic sizes provide a basis for explaining trends in many properties of the alkaline earth elements and their compounds. 

The periodic table is an arrangement of the elements that reflects their family relationships members of the same group typically show a smooth trend in properties. 

This chapter and the following two chapters survey the properties of the elements and their compounds in relation to their locations in the periodic table. To prepare for this journey through the periodic table, we first review the trends in properties discussed in earlier chapters. We then start the journey itself with the unique element hydrogen and move on to the elements of the main groups, working from left to right across the table. The same principles apply to the elements of the d and f blocks, but these elements have some unique characteristics (mainly their wide variety of oxidation states and their ability to act as Lewis acids), and so they are treated separately in Chapter 16. 

Ion formation is only one pattern of chemical behavior. Many other chemical trends can be traced ultimately to valence electron configurations, but we need the description of chemical bonding that appears in Chapters 9 and 10 to explain such periodic properties. Nevertheless, we can relate important patterns in chemical behavior to the ability of some elements to form ions. One example is the subdivision of the periodic table into metals, nonmetals, and metalloids, first introduced in Chapter 1. 

C noting periodic trends in the properties of known elements that surrounded the blank spaces in the periodic table... 

The periodic table organizes a remarkable amount of information about the chemical and physical properties of the elements. The information is organized in such a manner that trends in properties and important relationships can be readily identified. In this activity, you will identify several elements based on their properties and the properties of the surrounding elements in the periodic table. 

These are some of the general trends that relate the ionization potentials of atoms with regard to their positions in the periodic table. We will have opportunities to discuss additional properties of atoms later. 

For example, carbon and silicon are found within the same group in the periodic table. Considering the trends in a group, we would expect the oxides of these two elements, C02 and Si02, to display similar properties. However, Si02 is a solid with a quartz structure while C02 is a gas that has great importance in the life cycle. What can be the reason for these two compounds being so different ... 

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