Question

Fluorine atom contains 7 electrons in the outermost shell. But its valency is ‘1’. Explain.

Answer 1

• Valency is the number of electrons present in the outer most orbit of an atom. 
• The distribution of electrons in fluorine (atomic number 9) is 2, 7. 
• Hence the valency of fluorine could be 7. 
• But it is easier to fluorine to gain one electron for becoming octet. 
• Hence its valency is determined by subtracting seven electrons from 8 and which gives you a valency ‘1’ for fluorine.