Valency can be defined as the combining capacity of an element.The electrons present in the outermostmost shell of an atom are known as valence electrons and they determine the valency.The valence electrons take part in chemical reaction and they determine the chemical properties of the elements.Let us take an example,
Theatomic number of carbon is 6
Its configuration is =2,4 It means valency of carbon is 4.
Now, i think, you must have understood.
combining capacity...or say, the capacity of an atom..of an element to form bonds wid anothrr atom...is valency...
two kinds of valencies r drr--->>> electrovalency...n covalency..
electrovalency,,is wenn..two elements combine wid take-n-give ie.ionic bond formation..
n covalency..wen an element combines wid..its own atomz..or anothr elements atomz..wid..sharing ie. covalent bond formation... hope this helps u..!!:))
In chemistry, valence, also known as valency or valence number, is a measure of the number of bonds formed by an atom of a given element. "Valence" can be defined as the number of valence bonds a given atom has formed, or can form, with one or more other atoms. For most elements the number of bonds can very. The IUPAC definition limits valence to the maximum number of univalent atoms that may combine with the atom, that is the maximum number of valence bonds that is possible for the given element.
The valence of an element depends on the number of its valence electrons. A univalent (monovalent) atom, ion or group has a valence of one and thus can form one covalent bond. A divalent molecular entity has a valence of two and can form two sigma bonds or one sigma bond plus one pi bond.
Over the last century, the concept of valence evolved into a range of approaches for describing the chemical bond, including Lewis structures (1916), valence bond theory (1927), molecular orbitals (1928), valence shell electron pair repulsion theory (1958) and all the advanced methods of quantum chemistry.