Listed by Name, Symbol, and Atomic Number

Elements Listed by Name, Symbol, and Atomic Number... 

The atomic number of each of the elements is listed in the table on the inside of the back cover of this book. You will find there that each element has a distinctive name, symbol, and atomic number. A given element can be identified by any of these. For example, helium can be called by its name, helium, by its symbol, He, or by its atomic number, the element of atomic number 2. 

A lot of important information about the chemical elements is contained in a periodic table. The periodic table is a tabular illustration of the elements. Each element is listed with its chemical symbol and atomic number. The layout of the periodic table demonstrates a series of related, or periodic, chemical properties. Elements are arranged by increasing atomic number (the number of protons). Elements with similar properties fall into the same vertical columns. Elements with atomic numbers 83 or higher (above bismuth) are unstable and undergo radioactive decay over time. There aie many examples of this table and some of the interactive versions on the Internet provide many details about the full name of the element, isotopes, atomic mass, and other information. 

The separate question of names and symbols for the new elements has, unfortunately, taken even longer to resolve, but definitive recommendations were ratified by lUPAC in August 1997 and have been generally accepted. It is clearly both unsatisfactory and confusing to have more than one name in current use for a given element and to have the same name being applied to two different elements. For this reason the present treatment refers to the individual elements by means of their atomic numbers. However, to help readers with the nomenclature used in the references cited, a list of the various names that are in use or that have been suggested from time to time is summarised in Table 31.7. 

The number of protons in the nucleus determines the chemical properties of the element. That number is called the atomic number of the element. Each element has a different atomic number. An element may be identified by giving its name or its atomic number. Atomic numbers may be specified by use of a subscript before the symbol of the element. For example, carbon may be designated 6C. The subscript is really unnecessary, since all carbon atoms have atomic number 6, but it is sometimes useful to include it. Atomic numbers are listed in the periodic table and in Table 3-1. 

In this table you will find listed the 102 elements that are known today. Each element is described by its chemical symbol, its atomic number, its full name, and its atomic weight. 

On the following pages is a list of the elements with their symbols. The symbol and name of each element is followed by the element s atomic number, its physical state at ordinary temperatures if it is not a solid, the date of its discovery (which admittedly is debatable in some cases), and the source of its name. 

For simple elementary substances the smallest particle is called an atom. An atom is very small indeed a sheet of iron 1 //m thick would be 4300 atoms thick. These simple substances, which have as their smallest particle an atom, are called elements. There are 92 elements found in nature, including such commonplace materials as oxygen and carbon, sulphur and mercury, iron and lead. The Latin names of these elements can be abbreviated to one or two letters. These abbreviations are internationally recognized as symbols for the elements, e.g. O for oxygen, C for carbon, S for sulphur, Hg for mercury (hydrargyrum), Fe for iron (ferrum) and Pb for lead (plumbum). The 92 elements are listed by their symbols in a table called the Periodic Table (Fig. 1). The elements listed in vertical columns behave similarly in a chemical sense. The elements are given atomic numbers from 1 to 92. 

Atoms of a given element that differ in the number of neutrons, and consequently in mass, are called isotopes. The symbol C or simply (read "carbon twelve," carbon-12) represents the carbon atom with six protons and six neutrons. The number of protons, which is called the atomic number, is shown by Ihe subscript. The atomic number of each element is listed witii the name and symbol of Ihe element on the front inside cover of tire text. Because all atoms of a given element have the same atomic number, tire subscript is redundant and hence is usually omitted. The superscript is called tire mass number it is Ihe total number of protons plus neutrons in the atom. Some carbon atoms, for example, contain six protons and eight neutrons and are consequently represented as (read "carbon fourteen"). Several isotopes of carbon are listed in Table 2.2 T. 

In the following table elements are listed by letter symbol. The list includes the atomic number, element name, and the atomic weight of each element. 

The coordination conditions can be expressed in a chemical formula using a notation suggested by F. Machatschki (and extended by several other authors for recommendations see [35]). The coordination number and polyhedron of an atom are given in brackets in a right superscript next to the element symbol. The polyhedron is designated with a symbol as listed in Fig. 2.2. Short forms can be used for the symbols, namely the coordination number alone or, for simple polyhedra, the letter alone, e.g. t for tetrahedron, and in this case the brackets can also be dropped. For example ... 

This short index to the tryptamines lists the fifty-five chemical entries by their code names followed by a compact chemical name. All numbers, letters and atom symbols are ignored in the alphabetization. The abbreviation T is for tryptamine, C is for f -carboline, L is for ly sergamide and NL is for 6-norly sergamide. The long index includes all synonyms and is to be found in Appendix F. 

Atomic mass excess Listed in the headings for each isotope in this book is the mass excess for that atom (isotope) designated by the symbol A (Greek upper-case delta). The quantity A represents the mass of that isotope in a special way namely, the mass excess A is the difference between the actual mass of the neutral atom and the mass of a fictitious related atom having the same integer number A of nucleons but an atomic mass that is a factor A times greater than the atomic mass unit. 

The chemical symbols of elements are (in most cases) derived from their Latin names and consist of one or two letters which should always be printed in roman (upright) type. Only for elements of atomic number greater than 103, the systematic symbols consist of three letters (see footnote U to table 6.2). A complete list is given in table 6.2, p.94. The symbol is not followed by a full stop except at the end of a sentence. 

Metal-metal bonding is indicated by the italicized element symbols of the appropriate metal atoms, separated by an em dash and enclosed in parentheses, placed after the list of central atom names and before the ionic charge. The element symbols are placed in the same order as the central atoms appear in the name, i.e. with the element met last in the sequence of Table VI given first. The number of such metal-metal bonds is indicated by an arabic numeral placed before the first element symbol and separated from it by a space. For the purpose of nomenclature, no distinction is made between different metal-metal bond orders. 

Each nucleus is characterized by a definite atomic number Z and mass number A for clarity, we use the symbol M to denote the atomic mass in kinematic equations. The atomic number Z is the number of protons, and hence the number of electrons, in the neutral atom it reflects the atomic properties of the atom. The mass number gives the number of nucleons (protons and neutrons) isotopes are nuclei (often called nuclides) with the same Z and different A. The current practice is to represent each nucleus by the chemical name with the mass number as a superscript, e.g., 12C. The chemical atomic weight (or atomic mass) of elements as listed in the periodic table gives the average mass, i.e., the average of the stable isotopes weighted by their abundance. Carbon, for example, has an atomic weight of 12.011, which reflects the 1.1% abundance of 13C. 

The periodic table of the elements is based on atomic number and reactivity. The elements are represented by their chemical symbol, which is listed in large font below their respective full name. Atomic number and standard atomic weight (definitions are provided in Sections 2.1.1 and 2.1.1.1) are listed above and below the respective chemical symbol. Atomic weights of elements given within square brackets do not occur naturally. 

An internationally accepted chemical notation makes use of symbols to represent elements and compounds, and advises on naming chemical compounds. In this notation, the elements are represented by one or two letters, many of which are drawn from the elements Latin or Greek names. The number of atoms of an element in a molecule is represented by a subscript written after the symbol thus Au (the first two letters of aurum, the Latin name for gold) represents an atom of gold Cu (the first two letters of cuprum, the Latin name for copper), an atom of copper and C (the first letter of carbon), an atom of carbon O represents an atom of oxygen and 02, a molecule of oxygen. The symbols listed below provide examples of the presently accepted form of chemical notation ... 

A Inclusion of structural information. The names described so far detail ligands and central atoms, but give no information on stereochemistry. The coordination number and shape of the coordination polyhedron may be denoted, if desired, by a polyhedral symbol. These are listed in Table 4.4. Such a symbol is used as an affix in parentheses, and immediately precedes the name, separated from it by a hyphen. This device is not often used. 

Metal to metal bonding is indicated by the italicized atomic symbols separated by a long dash and enclosed in parentheses. Bond order may be indicated by an Arabic number above the long dash, e.g. (Mo—Mo). The bond order notation is listed after the central atom names and before the charge or Stock number. For examples see Table 16. 

Dalton noticed that oxygen combined with nitrogen in a ratio of 1 to 1.7 and 1 to 3.4 by weight. After testing this observation many times, he proposed the law of multiple proportions, where element weights always combine in small whole number ratios. Dalton pubUshed his initial list of atomic weights and symbols in the summer of 1803, which formally gave chemistry the vocabulary (symbol names) that we have come to know and memorize. 

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