1-elementsperiodictable - CHM151LL ELEMENTS IONS THE...

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Elements, Ions & the Periodic Table OBJECTIVES: This lab assignment will help you: learn the names and symbols of the most common elements, become familiar with the Periodic Table . DISCUSSION: The Elements Mastering chemistry has similarities to developing fluency in a foreign language; both processes progress by small incremental steps. When studying a new language, you first learn the alphabet. Likewise, as you begin the serious study of chemistry you must learn the names and symbols of the chemical building blocks of matter, the elements . Robert Boyle (1627-1691) defined elements as those pure substances that no chemical process can break down into simpler substances. Since the mid-twentieth century, each element has been assigned a unique atomic number , equal to the number of protons in an atom of that element, so a sample of a pure element contains only atoms with the same atomic number. Names & Symbols The American Chemical Society sets the official names of the elements used in this country. Other national chemistry societies make other choices, appropriate to their own language and history. The International Union of Pure and Applied Chemistry establishes the symbols, used worldwide. The element we call nitrogen goes by the name azot in French-speaking countries, our tungsten is Wolfram in German, and in Spanish, plata is the name used for silver , but we all use the same symbols (N for nitrogen, W for tungsten, Ag for silver). Each symbol contains one or two letters. To avoid confusion, we always write the first letter (and only the first letter) in UPPER CASE. That way, no one will wonder if you meant the compound nitrogen oxide (with formula NO) or if you really meant the element nobelium (symbol No). The Periodic Table The Periodic Table of the Elements first came into widespread use following Dmitri Mendeleev’s successful prediction of the existence of a previously unknown element, back in 1871. Since then, the Periodic Table’s format has evolved to keep up with new discoveries and new understandings. In its current form, the Table contains 18 numbered groups of elements (shown as vertical columns) and 7 numbered periods (shown as horizontal rows). Each group or family of elements has a characteristic set of chemical properties, so the Table summarizes much of our amassed knowledge of the chemistry of the elements. Groups 1, 2, and 13-18 comprise the main-group or representative elements , which have especially consistent chemical behavior. Groups 3-12 comprise the transition elements , and the lanthanum series (elements 58-71) and actinium series (elements 90-103) together make up the inner transition elements . A stair-step dividing line separates the many
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This note was uploaded on 02/28/2012 for the course CHEM 151 taught by Professor Wiley during the Spring '12 term at Mesa CC.

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1-elementsperiodictable - CHM151LL ELEMENTS IONS THE...

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