what is mean by Valency and also tell how to find a valency of an atom
Answers
Answer:The valency of an atom is equal to the number of electrons in the outer shell
Explanation:To calculate the valency of an element(or molecule, for that matter), there are multiple methods.
The first(and easiest) is simply to consult the periodic table. The elements are sorted into groups, and the elements in the groups(1–8 respectively) have the same valency as others in their group. For example, all of the elements in group 8 have eight electrons(high stability).
The second method is to look at the total number of electrons, and then calculate the valency(if you don’t know, remember to look at the atomic number - the number of electrons is always equal to the number of protons). The valency of an atom is equal to the number of electrons in the outer shell if that number is four or less. Otherwise, the valency is equal to eight minus the number of electrons in the outer shell. Once you know the number of electrons, you can easily calculate the valency. All atoms other than hydrogen have two electrons in the first electron shell, and up to eight electrons in each succeeding electron shell. For example, the atomic number of chlorine is 17, making the configuration of electrons would be 2, 8, and 7 - meaning, the valency of chlorine is 7. Oxygen has eight electrons, two in the first shell and six in the outer shell, giving it a valency of 2.
ANSWER
Valency can be defined as the combining capacity if an element or the number of Valence electrons is known as its valency.
Now the main thing is how to calculate it, so to calculate valence if any element we need to observe the valence electrons in the last shell or so called valence shell.
When, valence electrons is
1)Less than 5 i.e 1,2,3 and 4 then the valence will be same as the valence electrons in the element.
Example =>
-Carbon has a valency of 4 and its
electronic configuration is :>
2,4
We can see that it has 4 valence electrons and its valence is also 4.So the rule is followed.
2)More than or equal to 5 to 8.
i.e 5, 6, 7 and 8.
In these case what we do is subtract the no. if valence electrons from 8.
Example =>
-Nitrogen is an element which has valence of 3 and its electronic configuration is :>
2,5
Here the last shell has 5 electrons which means that the valency will be >
8-5 = 3(according to the rule)
Remember
1)Valency of an element shows its capacity to react and it can also be 0!
Example => All the inert gases has an Valency of 0 as has no tendency to react.All of them contain 8 electrons in the valence shell which means Valency Will be 8-8 = 0.