ELEMENTS ARE ORGANIZED IN THE PERIODIC TABLE BY THEIR PROPERTIES

The periodic table color-coded to show metals, nonmetals, and metalloids. 

If this silver mug were filled with boiling water, 

Mercury freezes at -40°Cand is a liquid at room temperature. 

1 H Zinc has a low melting point and is commonly of integrated circuits. 2 He 

Please put to rest any fear you may have about needing to memorize the periodic table, or even parts of it-better to focus on the many great concepts behind its V organization. 

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Elements Are Organized in the Periodic Table by Their Properties... 

ELEMENTS ARE ORGANIZED IN THE PERIODIC TABLE BY THEIR PROPERTIES... 

In this chapter we explored many of the rudiments of chemistry, including how matter is described by its physical and chemical properties and denoted by elemental and chemical formulas. We saw how compounds are different from the elements from which they are formed and how mixtures can be separated by taking advantage of differences in the physical properties of the components. Also addressed was what a chemist means by pure and how matter can be classified as element, compound, or mixture. Lastly, we saw how elements are organized in the periodic table by their physical and chemical properties. /Jong the way, you were introduced to some of the most important key terms of chemistry. With an understanding of these fundamental concepts and of the language used to describe them, you are well equipped to continue your study of nature s submicroscopic realm. 

The known elements were organized into the Periodic Table in the nineteenth century, first by atomic weight and then by atomic number. In both versions, uranium was the most extreme element. Since that time, the possibility of extension of the Periodic Table to unknown atomic numbers has captured the imaginations of many people, among them scientists and students of chemistry and physics. Can they be produced If so, what are their chemical and physical properties Does the Periodic Table have an extreme limit These questions are some of the most fundamental in the chemical sciences. 

The physical properties predict whether the spin number is equal to zero, a half integer, or a whole integer, but the actual spin number— for example, 1 /2 or 3/2 or 1 or 2— must be determined experimentally. All elements in the first six rows of the periodic table have at least one stable isotope with a nonzero spin quantum number, except Ar, Tc, Ce, Pm, Bi, and Po. It can be seen from Table 3.1 and Appendix 10.1 that many of the most abundant isotopes of common elements in the periodic table cannot be measured by NMR, notably those of C, O, Si, and S, which are very important components of many organic molecules of interest in biology, the pharmaceutical industry, the polymer industry, and the chemical manufacturing industry. Some of the more important elements that can be determined by NMR and their spin quantum numbers are shown in Table 3.2. The two nuclei of most importance to organic chemists and biochemists, and H, both have a spin quanmm number =1/2. 

A substance can be classified chemically in many ways. One of the simplest ways to classify a substance is as an element or a compound. An element is a pure substance that cannot be changed into a simpler substance by chemical means. Elements are the building blocks of nature all matter is composed of elements. The periodic table is a concise map that organizes chemical elements into columns (groups) and rows (periods) based on their chemical properties. Currently, there are 118 known chemical elements, with whole numbers 1 to 118. These numbers are referred to as the element s atomic number and give the number of protons in the nucleus of an atom of the element. For example, carbon s atomic number is 6 and each carbon atom has 6 protons in its nucleus. The first 92 elements occur naturally, and those above atomic number 92 are synthesized through nuclear reactions using particle accelerators. Element 118 was just confirmed in the fall of 2006, and by now, more elements may have been produced. 

Mendeleev and Meyer developed their periodic tables by trying to organize some recurring physical and chemical properties of the elements. Some of these properties are examined in this section. 

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