Periodic table modem

Our modem periodic table was developed independently in the late 1860s by Dimitri Mendeleev (Russian) and Julius Lothar Meyer (German). At that time, about 60 elements had been discovered, but nothing was known about atomic stracture. Lothar Meyer and Mendeleev had to work with elemental molar masses and other known elemental properties. 

Mendeleev was bolder in his interpretation than Lothar Meyer, and for this reason we honor him as the primary discoverer of the modem periodic table. A few elements did not fit the pattern of variation in combining numbers with molar mass. Mendeleev proposed that these irregularities meant that the element s molar mass had been measured incorrectly. For example, Mendeleev predicted that the correct molar mass of indium is 113 g /mol, not 75 g /mol, the value assigned at that time on the assumption that the formula for indium oxide is InO. Later experiments showed that the correct formula is L12 O3, and indium s tme molar mass is 114.8 g/mol. 

A family of colorless, inactive gases was unknown at the time Mendeleev conceived his periodic table. Eventually, these gases were discovered on Earth in the late 1890s. What group does this family occupy in the modem periodic table ... 

If there were a flag that represented the science of chemistry, it would be the periodic table. The periodic table is a concise organizational chart of the elements. The periodic table not only summarizes important facts about the elements, but it also incorporates a theoretical framework for understanding the relationships between elements. The modern periodic table attests to human s search for order and patterns in nature. As such, the periodic table is a dynamic blueprint for the basic building blocks of our universe. This chapter examines the development of the modern periodic table and presents information on how the modem periodic table is organized. 

Figure 15.1 Modem periodic table showing the transuranium elements. (Figure also appears in color figure section.)...

Scientists developed the modem periodic table by looking for regularities. 

A modem periodic table. Some periodic tables. 

The separation of elements into metals and non-metals is not clear cut and without ambiguity. The fairly obvious division between metals and non-metals is shown by a thick steeped line in the following shortened figure of the modem periodic table. Some of the elements next to the thick steps, such as germanium, arsenic and antimony have similarities to both metals and non-metals and are named... 

In the modem periodic table the elements have been arranged in the order of their increasing atomic numbers. 

Periodic table An arrangement of the chemical elements in order of their atomic numbers. Arranged as horizontal periods and vertical groups or families of elements with similar properties. Its initiation is attributed to the nineteenth century Russian chemist Mendeleyev. A modem periodic table, which differs significantly from early ones, is shown on page 283. 

First things first, you need to understand the nature of elements, and their oxidation states (number of bonds). Every single element is capable of forming chemical bonds with other elements (with the exception of a few noble gases ). The oxidation states are what determines how many bonds a particular element can form, and to what other elements. When elements combine, they form chemical compounds. All of the atoms within a chemical compound show specific oxidation states. Oxidation states are not really states, but definitions of bonding, which are dictated by each individual element. Each element can form any where from either 0 to 7 bonds. These numbers represent the number of bonds the element can form (look at a modem periodic table, such that included in the Merck Index —the oxidations states are written in the upper left comer of each element). These numbers clearly indicate the number of bonds each element is capable of forming. 

E The modem periodic table is based upon atomic number, which is defined by the number of protons in the nucleus. 

In Section 1.2, we learned a few of the properties of sulfur and of iron. Do we have to learn the properties of all 100 or so elements individually, or are there some ways to ease that burden For over 140 years, chemists have arranged the elements into groups with similar chemical characteaisiics, which makes it easier to learn their properties. This grouping of the elements has been refined to a high degree, and the modem periodic table is the result. A full periodic table is shown inside the front cover of this book. The elements numbered 104 and up in that table have only recently been produced and in such infinitely small quantities that their chemical properties are unmeasured. Therefore, we will almost totally ignore them in the remainder of this book. 

In the modem periodic table, a horizontal row of elements is called a period, and a vertical column is a group or family. The traditional designations of groups in the United States differ from those used in Europe. The International Union of Pure and Applied Chemistry (lUPAC) has recommended that the groups be numbered 1 through 18, a recommendation that has generated considerable controversy. In this text, we will... 

The mass of an atom of chlorine, or any other element, is measured relative to something, just as we measure length using a standard measured metre rule. The standard has to be agreed worldwide and has to be constant, so the isotope of carbon with a mass number of 12 was chosen to be the standard, and everything is measured relative to /12 of The modem periodic table the mass of the carbon-12 isotope,... 

Research the life of a scientist, other than Mendeleev, who contribnted to the development of the modem periodic table of elements. Write a brief biography of this person and detail his or her scientific accomplishments. 

In 1869 both Mendeleev and Meyer, working separately, published nearly identical classification schemes for the elements that were the forerunners of the modem periodic table. Although scientists of that time had no knowledge of atomic numbers, both schemes ordered the elements in nearly correct order from lowest to highest atomic number. Which of the following is the most likely explanation ... 

A modem periodic table usually shows the atomic number along with the element symbol. As you already know, the atomic nnmber also indicates the number of electrons in the atoms of an element. Electron confignrations of elements help to explain the recurrence of physical and chemical properties. The importance and usefulness of the periodic table lie in the fact that we can use our understanding of the general properties and trends within a group or a period to predict with considerable accuracy the properties of any element, even though that element may be unfamiliar to us. 

Electron configuration determines the properties of an element. The modem periodic table classifies the elements according to their atomic numbers, and thus also by their electron configurations. The configuration of the valence electrons directly affects the properties of the atoms of the representative elements. 

Describe the general layout of a modem periodic table. 

The availability, only, of numerical data for the electron distributions in atoms other than hydrogen and the increasing complexity of that data with the atomic number of the atom, would be a serious limitation on our comprehension of atomic and molecular theory. In Chemistry the orbital is fundamental to the understanding of all the body of data that can be catalogued using the modem Periodic Table. It is an essential concept, too, in modem bonding theory, because general mles can be established, based on orbital interactions. 

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