Elements their Symbols and Valency
In chemistry an element can be considered as the simplest form of any matter which cannot be further decomposed by using any chemical methods. All elements are composed of smaller particles which are called as atom which take part in all the chemical reactions. In other words, an element is composed of similar types of atoms. All known elements are arranged in the long form of periodic table on the basis of their atomic number.
They can exist either as atom or as molecule in nature. For example diamond and graphite are carbon element but show different properties as well as appearance. At the same time the atomic number (number of protons) and electrons are same in both diamond and graphite because both are composed of carbon.
We can see all the examples of elements in the periodic table. Pure elements are composed of atoms with same number of protons. All elements can be represented with the help of atomic symbols such as symbol of nitrogen is N, helium as He and Pb for lead. We can see the atomic symbols in periodic table. Some of the elements are naturally occurring elements while some are artificially synthesised in laboratory.
If the symbol of elements contains only one alphabet, then it is written in capital such as K, N, O, F etc. In the presence of two alphabets are their then the 1st one is capital and the 2nd one is a small letter such as iron must be written as Fe, calcium as Ca etc.
Valency represents the combining capacity of an element. It represents the number of atoms which combines with other elements during chemical reaction. The valency of element depends upon the number of valence electrons in the element.
All elements loose or gain that number of electrons by which they can acquire the Nobel gas or octet configuration in their valence shell. As such configuration provides stability to them. In other words, the valence shell configuration of an element determines the valency of an element. For example; alkali metals show 1+ valency as they have one electron in their valence shell which can be easily lose to for electropositive ion or cation. Similarly alkaline earth metals show 2+ valency due to ns2 valence shell configuration.
The d and f-block elements show variable valency due incomplete valence shell. The valency also determines the chemical reactivity of the element and their bonding with other elements. If one element show more than one valency then the lower valency is indicated by –ous and the higher valency is indicated by the letters – ic such as Cupric (Cu2+) and Cuprous (Cu+) or Mercuric (Hg2+) and Mercurous (Hg+) or Ferric (Fe3+) and Ferrous (Fe2+). Valency helps in the naming of compounds as well.