Question

why is the valency of some elements +4 why can't it be -4 because it has the capability of gaining or losing 4 electrons why does it only fain​

Answer 1

Answer:

1)The reactivity of elements is explained as their tendency to attain a completely filled outer shell, that is, attain noble gas configuration.

2)Taking carbon for an instance; it has four electrons in its outermost shell and needs to gain or lose four electrons to attain noble gas configuration.

3)It could gain four electrons forming C^4- anion. But it would be difficult for the nucleus with six protons to hold on to ten electrons, that is, four extra electrons.

4)It could lose four electrons forming C^4+ cation. But it would require a large amount of energy to remove four electrons leaving behind a carbon cation with six protons in its nucleus holding on to just two electrons.

5)Carbon overcomes this problem by sharing its valence electrons with other atoms of carbon or with atoms of other elements.

6)The shared electrons belong to the outermost shells of both the atoms and lead to both atoms attaining a noble gas configuration.