Valency of an Element:
The valency of an element is a measure of its combining capacity with other atoms to form chemical compounds. It determines the number of electrons an atom can gain, lose, or share in order to achieve a stable configuration. It is a fundamental concept in chemistry and is essential in understanding the formation of chemical bonds and the behavior of elements in chemical reactions.

Valence Electrons:
Valence electrons are the electrons present in the outermost energy level or shell of an atom. These electrons are involved in chemical bonding and determine the valency of an element. The valence electrons are located in the s and p orbitals of the highest energy level.

Relationship between Valence Electrons and Valency:
The number of valence electrons an atom possesses directly influences its valency. The valency of an element can be determined by analyzing the number of valence electrons in its atom. The following relationships exist between the number of valence electrons and valency:
1. Noble Gases: Noble gases have stable electronic configurations and exhibit little reactivity due to their complete outermost energy levels. They have 8 valence electrons, except for helium which has 2. Therefore, the valency of noble gases is 0.

2. Groups 1 and 2: Elements in Group 1 (alkali metals) have 1 valence electron, while elements in Group 2 (alkaline earth metals) have 2 valence electrons. These elements tend to lose their valence electrons to achieve a stable configuration, so their valency is +1 and +2 respectively.

3. Groups 13 to 17: Elements in Groups 13 to 17 have valence electrons ranging from 3 to 7. They tend to gain or lose electrons to achieve a stable configuration. The valency of these elements can be determined by subtracting the number of valence electrons from 8. For example, Group 16 elements have 6 valence electrons, so their valency is 8 - 6 = -2.

4. Transition Metals: Transition metals have variable valencies as they can form multiple positive ions by losing different numbers of electrons from their outermost energy levels. The valency of transition metals is determined by their electron configuration and the stability achieved by losing electrons.

5. Nonmetals: Nonmetals in Groups 14 to 17 (except for hydrogen) tend to gain electrons to achieve a stable configuration. Their valency can be determined by subtracting the number of valence electrons from 8. For example, oxygen has 6 valence electrons, so its valency is 8 - 6 = -2.

In summary, the number of valence electrons an atom possesses determines its valency. Elements tend to gain, lose, or share electrons to achieve a stable configuration, and their valency reflects the number of electrons required to do so. The concept of valency is crucial in understanding the behavior of elements in chemical reactions and the formation of compounds.

The valency of an element is the combining capacity of the elementelectrons present in the outermost shell are called valence electron and these electron determine the valency of an atom and their chemical propertiesteen Representative elements the valency is equal to the number of Valence Electronsfrom 14th group onwards the valence electron maybe 8 - valence electrons or Valence Electrons because they have to attend noble gas octet configurationtransition elements exhibit variable valency