A common form of elemental phosphorus is the tetrahedral P₄ molecule, where all four phosphorus atoms are equivalent: 

Draw a Lewis structure for a linear P₄ molecule that satisfies the octet rule. Does this molecule have resonance structures?

Video transcript

Hello Everyone in this video we're trying to draw the lewiS structure for arsenic acid and we have to keep in mind the octet rule. So first things first, let's go ahead and count the valence electrons. So from hydrogen we have three items of hydrogen. Each hydrogen atom will contribute one fans electron. So three times one is equal to three. Now let's do the same thing for arsenic. So we have one item of arsenic. Each atom will contribute five valence electrons. So one times five is five. Now for oxygen we have three items of oxygen. Each will contribute six vans electrons. Three times six is 18. Now we take the sum of all these fans electrons to get a total of fans electrons in our arsenic um acid molecule. Alright, so oxygen prefers to have two bonds and arsenic prefers to have three bonds. So with that in mind we can have arsenic as our central atom connected to three oxygen atoms. And because hydrogen can only be a terminal item since it can only hold two electrons, it will be at the end of our oxygen's. And of course we need to fill in the lone pairs to give it its octet rule and one more long pair on an arsenic to fulfill its octet. So this right here is going to be our final lewis structure for our arsenic acid molecule. Thank you all so much for watching