Question

In which 2 groups do we find elements that most likely have a positive valence? Why is this so?

Answer 1

Valency of an element is determined by the number of electrons of its atoms, that take part in a chemical reaction (to attain a completely filled outermost shell). When an atom loses electrons, it is said to have a positive valency. On the other hand, atoms that accept electrons have a negative valency.

The elements that most likely have a positive valency would be found in group 1 and 2. This is because elements of these groups can have a maximum of only one or two electrons in the outermost shell. This makes it easier to lose electrons.

With an increase in number of electrons in the outermost shell, the nuclear charge (between electrons and protons) increases. This makes it tough for elements with more than two electrons in the outermost shell to lose electron.

Examples of elements of group 1 are sodium, potassium, etc., and of group 2 are magnesium, calcium, etc.