The atom of an element has 9 protons, 9 electrons and 10 neutrons.
(i) What is the atomic number of the element?
(ii) Predict the valency of the element.
(i) The atomic number of element = Number of protons = 9
The element is fluorine (F).
(ii) Electronic distribution =2,7(K,L)
In order to complete its octet it requires one electron so, valency =8 - 7 = 1
The valency of the element is 1.