More About the Periodic Table

In Chapter 4 we described the development of the periodic table, some terminology for it, and its guiding principle, the periodic law. 

The properties of the elements are periodic functions of their atomic numbers. 

Now we can classify the elements according to their electron configurations, which is a very usefiol system. 

Representative Elements. The A group elements in the periodic table are called representative elements. Their last electron is assigned to an outer shell s ox p orbital. These elements show distinct and fairly regular variations in their properties with changes in atomic number. 

Unless otheiwise noted, all content on this page is Cengage Learning. 

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We will learn much more about the periodic table as we continue with our study of chemistry. Meanwhile, when an element is introduced in this text, you should always note its position on the periodic table. 

More About the Periodic Table Periodic Properties of the Elements... 

To find out more about the Periodic Table, visit the Glencoe Science Web site... 

To learn more about alternate periodic tables, visit the Chemistry Web site at chemistrymc.com... 

Perhaps the most interesting thing about the Periodic Table of Elements is how much information is hidden in it. To the untrained eye, the periodic table appears to only show the elemental symbols, elemental names, atomic numbers, and atomic masses. However, someone who knows a bit more chemistry can squeeze much more information out of the same table. You will learn to use the periodic table to check your electron configurations, orbital notations, and Lewis dot notations. You will also learn to use the periodic table to check many relative properties of the elements, such as reactivity, electronegativity, and metallic character. All of this information is there, if you know how to use the table correctly. It is certainly in your best interest to learn as much about the periodic table as possible, because you are allowed to make use of it on many exams and quizzes. If you are able to extract all kinds of information from it, it becomes an incredibly useful cheat sheet, except that you re allowed to use it ... 

The diagonal line or stairway that starts to the left of boron in the periodic table (Figure 2.7, page 31) separates metals from nonmetals. The more than 80 elements to the left and below that line, shown in blue in the table, have the properties of metals in particular, they have high electrical conductivities. Elements above and to the right of the stairway are nonmetals (yellow) about 18 elements fit in that category. 

The decrease in atomic radius moving across the periodic table can be explained in a similar manner. Consider, for example, the third period, where electrons are being added to the third principal energy level. The added electrons should be relatively poor shields for each other because they are all at about the same distance from the nucleus. Only the ten core electrons in inner, filled levels (n = 1, n = 2) are expected to shield the outer electrons from the nucleus. This means that the charge felt by an outer electron, called the effective nuclear charge, should increase steadily with atomic number as we move across the period. As effective nuclear charge increases, the outermost electrons are pulled in more tightly, and atomic radius decreases. 

Exercises 21-1 and 21-2 pose some of the simplest questions we can ask about the alkaline earths. The periodic table arranges in a column elements having similar electron configurations. We can expect elements on the left side of the periodic table to be metals (as magnesium is). Furthermore, we can expect that the elements in a given column will be more like each other than they will be like elements in adjacent columns. Thus, when we find that the chemistry of magnesium is almost wholly connected with the behavior of the dipositive magnesium ion, Mg+l, we can expect a similar situation for calcium, and for strontium, and for each of the other alkaline earth elements. This proves to be so. 

Suppose we get a little more sophisticated about our question. The more advanced student might respond that the periodic table can be explained in terms of the relationship between the quantum numbers which themselves emerge from the solutions to the Schrodinger equation for the hydrogen atom.5... 

The next step in our journey takes us from hydrogen and its single electron to the atoms of all the other elements in the periodic table. A neutral atom other than a hydrogen atom has more than one electron and is known as a many-electron atom. In the next three sections, we build on what we have learned about the hydrogen atom to see how the presence of more than one electron affects the energies of... 

The periodic table is a useful way to organize chemical properties. To help you see the patterns, the periodic table on the inside front cover of this book highlights the various groups of elements. As you learn more about chemical structure and behavior, you will discover the principles that account for similarities and differences in the chemical behavior of the elements. 

What is the world made of The ancient Greeks speculated about earth, air, fire, and water today we turn to the periodic table for more reliable information. The story of how we got from there to here is full of fascinating people, and in this elegant, entertaining book, Paul Strathern introduces us to ancient philosophers, medieval alchemists, and the earliest chemists—and to dimitri Mendeleyev, the card-playing nineteenth-century Russian who claimed that the answers came to him in a dream"... 

Why evolution only made use of these elements cannot be answered. The fact that the Periodic Table holds the possibility of allowing something as wonderful as life to come into existence is and remains a mystery. But not only that at the end of the development, a being appears on the screen that is able to discover these very elements and to find out about their substructures. And the fact that we can ponder over this is even more mysterious. 

There were no smooth transitions, but really huge jumps. It should all have become crystal clear when the neighbor of fluorine, neon, was discovered. Let us consider this picture here is the aggressive fluorine that ravenously rips out an electron from the shell of just about any element to make itself comfortable as the fluoride anion. But add a proton and electron (as well as a neutron, as we now know), and the new element is so inert that even today no chemical compound of neon is known. A more obvious jump cannot be imagined. It is a pity that our chemical forefathers did not consider this aspect. After all, it was they who in their research of the Periodic Table brought... 

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