Classification of Elements
The periodic table forms the basis for the classification of elements. It comprises a list of all known chemical elements based on their Atomic Number. Commonly the periodic table classifies the elements into eight distinct groups depending on their chemical properties. –
- Alkali metals.
- Alkali earth metals.
- Basic metals.
- Noble gases.
- Non metals
- Transition metals.
Most people associate the chemical elements with being a metal or a non- metal, and since they occupy much space in the periodic table we will take a look at these two classifications of element.
Metal. A metal is usually solid with a characteristic metallic luster. It has the properties of being malleable and ductile, (can be bent and stretched). A metal is also a good conductor of both heat and electricity. Typical metals include the elements Copper, Tin, and Lead.
Non- Metal. Non metals usually exist in the gaseous form and do not conduct electricity, although Carbon in the form of graphite will conduct. The oxides of non metals are commonly gaseous too and can often be acidic. The chlorides of non metals tend to form co-valence bonds which can form either solid or liquid compounds. Typical non-metals are Oxygen and the halogen Chlorine.
The difference between metals and non metals can be recognized by considering the electron configuration in the outermost shell of an atom of the element.
Metals located on the left hand side of the periodic table tend to have fewer electrons within this outer shell. Many metal atoms bond together to form the stable metal, which is able to conduct electricity; electricity in reality being electron flow.
On the other hand non metals located on the right hand side of the periodic table posses fewer electrons in their outer shell, and tend to form co-valence bonds with other atoms to form gases.
When a metal combines with a non metal such as oxygen or chlorine the metal gives up an electron and becomes a positive metallic ion, while the non- metal gains an electron and becomes a non metal negative ion. The two ions then combine by ionic bonding with the negatively charged ion being attracted to the positively charged ion to form a compound.
In the case of non-metals they tend to bond together covalently by a process of sharing their outer electrons to reach a stable configuration of both atoms from differing elements; having the appearance of possessing eight electrons in each of their outer shells. This is a stable energy configuration.
By classifying metals and non-metals this way helps reach an understanding of the way atoms combine to form a multitude of different chemical compounds.
Filed under: Science
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