Question

phosphorus has only 3 unpaired electrons but can form pcl5. Explain​

Answer 1

Answer:

Valency is defined as the combining power of an element with other atoms. An element can combine with other elements either by losing electrons or by gaining electrons in the outermost shell. Phosphorus has 5 electrons in the outermost shell. By octet rule atom tends to combine in such a way that they'll have 8 electrons in the valence shell. So phosphorous either gain 3 electrons or lose 5 electrons(phosphorous has 8 electrons in the second shell) while combining. So it has two valancies i.e) 5 and 3.