Metal and non metal

Metallic Bonding

Silver, a typical metal, consists of a regular array of silver atoms that have each lost an electron to form a silver ion. The negativly charged electrons distribute themselves throughout the entire piece of metal and form nondirectional bonds between the positive silver ions. This arrangement, known as metallic bonding, accounts for the characteristic properties of metals: they are good electrical conductors because the electrons are free to move from one place to another, and they are malleable (as shown here) because the positive ions are held together by nondirectional forces. A force applied to a malleable substance shifts the positions of the atoms without breaking the bonds that hold them together.

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The structure of the atom, in particular the configuration of the electron cloud, is responsible for the obvious physical differences between metals and nonmetals. Metals have a characteristic luster, are opaque, can be hammered and drawn into various shapes, and conduct electricity. Nonmetal elements, on the other hand, are often gases, and, if solid, nonmetals are generally brittle, sometimes transparent, and do not conduct electricity.

The atoms of metals have outer shells that contain few electrons and are nowhere near filled (and therefore lack the stability of a noble gas). As a result, all metals tend to easily lose some of these outer electrons. This means, chemically, that metals tend to form positively charged ions, or positively charged atoms or molecules, when they enter into chemical combination. Physically, the fact that the outer shells of metal atoms are unfilled means that these “loose” electrons can flow and enable metals to conduct electricity; this fact also accounts for the mechanical properties of metals. Nonmetals, by contrast, have outer shells that are nearly filled (up to the stable grouping of eight electrons); in their chemical reactions they tend to add electrons to achieve the state of a stable noble gas. By adding electrons, nonmetals form negatively charged ions. They can also add electrons by sharing them with another atom and forming a covalent bond. The noble gases, with exactly eight electrons in their outer shells (two in the case of helium), are nonmetals.

There are many more metals than nonmetals, especially among elements of high atomic weight. A partial explanation of this fact is that the added electrons go mostly to fill the incomplete inner shells, leaving only two or three electrons in the outer shell.