Elements periodic table, Inside front cover

In the periodic table (inside front cover), locate five elements for which mass numbers rather than atomic masses are given. 

Solution To calculate the molar mass of a compound, we need to sum all the molar masses of the elements in the molecule. For each element, we multiply its molar mass by the number of moles of that element in one mole of the compound. We find molar masses for the elements in the periodic table (inside front cover of the text). 

For example, polonium was named after Poland, francium after France, and americium after the United States of America. Still other elements were named after scientists. Curium was named after Marie Curie, and mendelevium after Dmitri Mendeleev. Every element s name, symbol, and atomic number are included in the periodic table (inside front cover) and in an alphabetical listing (inside back cover) in this book. 

The modern periodic table. Today s table (inside front cover) includes 52 elements not known in 1870 and, most importantly, arranges the elements by atomic number (number of protons) not atomic mass. 

There is no single best form of the periodic table since the choice depends on the purpose for which the table is used. Some forms emphasize chemical relations and valence, whereas others stress the electronic configuration of the elements or the dependence of the periods on the shells and subshells of the atomic structure. The most convenient form for our purpose is the so-called long form with separate panels for the lanthanide and actinide elements (see inside front cover). There has been a lively debate during the past decade as to the best numbering system to be used for the individual... 

In the periodic table, atomic masses are listed directly below the symbol of the element. In the table on the inside front cover of this text, atomic masses are cited to four significant figures. That ordinarily will be sufficient for our purposes, although more precise values are available (see the alphabetical list of elements on the inside back cover). 

The dozen or so elements that are normally found as gases include nitrogen, oxygen, fluorine, helium, neon, argon, krypton, xenon, and chlorine. Where are these placed in the periodic table (see inside front cover) ... 

All molar masses quoted in this text refer to these average values. Their values are given in Appendix 2D. They are also included in the periodic table inside the front cover and in the alphabetical list of elements inside the back cover. 

Figure Db shows the periodic table. Notice that rows 6 and 7 are quite long, which makes the table rather cumbersome. Eor convenience, 14 elements in the sixth row and 14 in the seventh row usually are separated from the rest of the table and placed beneath the main portion, as shown in Eigure W7 and on the inside front cover of the book. This is the most common format for the periodic table.

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. 

B Main group elements are in the A families, while transition elements are in the B families. Metals, nonmetals, metalloids, and noble gases are color coded in the periodic table inside the front cover. 

Figure 1.1 Principal features of the periodic table. The International Union of Pure and Applied Chemistry (IUPAC) now recommends Arabic group numbers 1-18 in place of the traditional Roman I—VIII (A and B). Group names include alkali metals (1), alkaline earth metals (2), coinage metals (11), chalcogens (16), and halogens (17). The main groups are often called the s,p block, the transition metals the d, block elements, and the lanthanides and actinides the / block elements, reflecting the electronic shell being filled. (See inside front cover for detailed structure of the periodic table.)...

The first thing you must be able to do in order to predict molecular shapes is to draw an electron-dot formula, so we ll tackle that subject first Including H, there are 16 active nonmetals for which you should know the numbers of valence electrons in the uncombined atoms Except for H (which has only one s electron), these elements are all found to the right of the diagonal in the p block of the periodic table (see inside front cover) Each atom has two v electrons in its valence shell, the number ofp electrons is different for different atoms (Basically, we are uninterested in metals here, metals rarely form predominantly covalent bonds, but tend to form ionic bonds ignore the noble gases, with an already filled s-yi6 unreactive )... 

The molar masses of elements are determined by using mass spectrometry to measure the masses of the individual isotopes and their abundances. The mass per mole of atoms is the mass of an individual atom multiplied by the Avogadro constant (the number of atoms per mole). However, there is a complication. Most elements occur in nature as a mixture of isotopes we saw in Section B, for instance, that neon occurs as three isotopes, each with a different mass. In chemistry, we almost always deal with natural samples of elements, which have the natural abundance of isotopes. So, we need the average molar mass, the molar mass calculated by taking into account the masses of the isotopes and their relative abundances in typical samples. All molar masses quoted in this text refer to these average values. Their values are given in Appendix 2D. They are also included in the periodic table inside the front cover and in the alphabetical list of elements inside the back cover. 

Most elements occur naturally as a mixture of different isotopes. If you look at the periodic table inside the front cover, you ll see listed below the symbol for each element a value called the element s atomic mass. (The unit amu is understood but... 

The atonuc numbers are the numbers of protons, in each case 17, so the atoms are both atoms of the same element—chlorine. (See the periodic table inside the front cover.) The mass number of the first atom is 17 + 18 = 35, and the mass numbea of the second is 17 + 20 = 37. Thus, the atoms have the same atomic number but different mass numbers. Their properties are essentially the same because they are the same element, but their masses are somewhat different. They are isotopes of each other Cl and Cl. 

Which lanthanide element and which transition element have only radioactive isotopes Refer to the periodic table inside the front cover of this book. (Elements in the periodic table with atomic masses in parentheses have only radioactive isotopes.)... 

The modern periodic table (Fig. 3.f and the inside front cover of this book) places elements in groups (arranged vertically) and periods (arranged horizontally). 

The atomic number (symbol is Z) of an element is defined as the number of protons in the nucleus. In the periodic table, elements are arranged in order of increasing atomic numbers. These are the red numbers above the symbols for the elements in the periodic table on the inside front cover. For example, the atomic number of silver is 47. 

See Figure 1.22 and the inside front cover of this book. You should start learning the names and positions of elements that you do not know. Start with the alkali metals and the alkaline earths. Then learn the elements in the p block. A blank periodic table can be found on the inside back cover of this book. You should make several photocopies of it and should test yourself from time to time, especially after studying each chapter. 

The value of Z identifies the element as Sn (see the periodic table inside the front cover of the book). 

Today s periodic table, which appears on the inside front cover of the text, resembles Mendeleev s in most details, although it includes 49 (and still counting) elements that were unknown in 1870. The only substantive change is that the elements are now arranged in order of atomic number (number of protons) rather than atomic mass. 

As the number of electrons increases, they are forced by virtue of Pauli s exclusion principle to occupy higher and higher energy levels, i.e., higher n values. This in turn leads to the aufbau principle, the periodic table (see inside front cover), and a unique electronic configuration for each element as summarized in Table 2.2. 

I Periodic Table of the Elements Inside Front Cover... 

Commonly known elements include copper, gold, oxygen, mercury and sulfur. At present, there are 111 named elements (see the Periodic Table, shown on the inside front cover, which is an arrangement of all known elements) of which 90 have been found naturally the others have been made by scientists. 

The modern-day Periodic Table, shown on the inside front cover of this book, has the atoms of elements listed in order of increasing atomic number. The numbered vertical columns are called groups (or families) and elements in the same group often have similar properties. Some of the groups have special names ... 

A list of the most common elements and their symbols is given in Table 4.3. You can also see the elements represented on a table in the inside front cover of this text. We will explain the form of this table (which is called the periodic table) in later chapters. 

---