Elements, or atoms, are the basic building blocks of all tangible materials in the universe. There are 92 natural elements, or material atoms, almost all of which are stable, from hydrogen, atomic number 1, or element 1, to uranium, or element 92. Elements of higher atomic weight than uranium are made, but they are unstable, their time decay being measured progressively as half-life.
The atom gets its name from the Greek word atomos, meaning indivisible, and it is not divisible by ordinary chemical means. The elements are used either alone or in combination for making useful products. They combine either as mechanical mixtures or as chemical compounds. In a mixture each element retains its original nature and energy, and the constituents of the mixture can be separated by mechanical means. In chemical compounds of two or more elements, the original elements lose their separate identities; the new substance formed has entirely different properties, and the atomic energy stored within the compound is not equal to the sum of the elemental energies. The atoms in chemical compounds are bonded by electrons. An alloy is usually a combination of chemical compounds and mixtures, the metal mixtures in the matrix being gaged by their maximum fused or liquid solubility, known as the eutectic point. With the elements the number of different compounds, or useful substances, that can be made by varying the combinations of elements and the proportions is infinite.
The known...
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