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

(b) How many P-P bonds are there in the molecule?

Video transcript

Hey everyone, we're asked to identify two possible lewis structures for arsonists acid first. Let's go ahead and identify the total number of valence electrons will have. Starting with our hydrogen, we have three of hydrogen and so we're going to multiply that by one valence electron which will get us to a total of three. Next looking at our arsenic, we know that this is in our group five A. So we're going to multiply one times five to get five valence electrons. And lastly looking at our oxygen, we have three of oxygen and we're going to multiply this by six since it's in our group six A. This will get us to a total of 18, Adding these three values up. We get 26 valence electrons. Now let's go ahead and draw out our structures were given a hint right here, we're told that one structure has arsenic with three covalin bonds and the other has arsenic with five covalin bonds. Starting off with the three covalin bonds, we know that arsenic is going to be our central atom. And when we create three covalin bonds, we can go ahead and attach our oxygen's since those hydrogen are going to be attached to our oxygen's now completing our total number of valence electrons. We're going to add two lone pairs onto each oxygen. And lastly to complete arsenic octet, we add a lone pair onto our arsenic as well. So this is going to be one of the possible lewis structures for arsonist acid. Now let's look at our next structure, we're told that arsenic will have five covalin bonds. So drawing this out again, we know oxygen is going to be connected to our arsenic and we can go ahead and create a double bond between one oxygen, and we can go ahead and add our hydrogen onto an oxygen. So it would be the oxygen that is single bonded to our arsenic. And since we have one last hydrogen will make that fifth Covalin bond by adding that hydrogen onto arsenic. Now, to complete our octet for oxygen's will go ahead and add two lone pairs onto each, and arsenic is able to violate our octet rule, which is why we have five Covalin bonds here. So this is going to be our final structures for this question. Now, I hope this made sense. And let us know if you have any questions.