Element A substance that cannot be decomposed into simpler substances by chemical

Element a substance that cannot be decomposed into simpler substances by chemical or physical means. (2.1)... 

As we noted above, an element is a substance that cannot be decomposed into simpler substances by any chemical reaction. There are 92 elements that occur in nature, in widely varying amounts, and several more have been created in particle accelerators. In order to understand the molecules of life, we need to understand something about several of these elements, above all about carbon. 

Elements and compounds constitute the world of pure substances. An element is a substance that cannot be decomposed by any chemical reaction into simpler substances. Elements are composed of only one type of atom and all atoms of a given type have the same properties. Pure substances cannot be separated into other kinds of matter by any physical process. We are familiar with many pure substances water, iron, mercury, iodine, helium, rust, diamond, table salt, sugar, gypsum, and so forth. Among the pure substances listed above, iron, mercury, iodine, diamond (pure carbon), and helium are elements. We are also familiar with mixtures of pure substances. These include the air that we breathe, milk, molasses, beer, blood, coffee, concrete, egg whites, ice cream, dirt, steel, and so on. 

CHEMICAL ELEMENTS. A chemical element may be defined as a collection of atoms of otic type which cannot be decomposed into any simpler units by any chemical transformation, but which may spontaneously change into other units by radioactive processes A chemical element is a substance that is made up of but one kind of atom. Of the over 100 chemical elements known, only 90 tire found in nature. The remaining elements have been produced in nuclear reactors and particle accelerators. Theoretical physicists do not all agree, but some believe that fission-stable nuclei should exist at atomic numbers 109. 114. and 126. Claims thus lur have been made for the discovery, isolation, or creation of elements up to 110. The element with the highest atomic number officially named and entered into the formal table of atomic weight is darmstudlium (Dx) with an atomic number of 110. 

Element unit negative charge (1.6022 x 10 19C) and exists in the region around the positively-charged nucleus. A substance that cannot be decomposed by any chemical reaction into simpler substances. A type of matter composed of one kind of atom. 

Elements Millions of substances have been characterized by chemists. Of these, a very small number are known as elements, from which all other substances are made. Lavoisier was the first to establish an experimentally useful definition of an element. He defined an element as a substance that cannot be decomposed by any chemical reaction into simpler substances. In 1789 Lavoisier listed 33 substances as elements, of which more than 20 are still so regarded. Today 114 elements are known. Some elements are shown in Fignre 1.14. ... 

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