Which of the following statements are true?

i. The overall dipole moment of a molecule is the vector sum of its individual bond dipoles.

ii. If atoms A and B in an AB𝑛 molecule have different electronegativities, then the AB𝑛 molecule must have a nonzero dipole moment.

iii. The bond dipoles in a tetrahedral AB4 molecule cancel one another.

Video transcript

Hello everyone today. We've been given the following problem, identify the compounds that will have a net or non zero dipole moment justify your answer and show the direction of each. So first we will start with our first option which is arsenic. Pensa chloride. So with arsenic chloride We have arsenic here. Arsenic is a group five a element and therefore has five valence electrons. Chlorine is a group seven a element and therefore has seven valence electrons. However, there's five of them. So we have a 35 And then when you add them up we have 40 electrons total to construct our figure. So when we have a structure such as arsenide, arsenic, pensar clo Ron, we have one Arsenic right there in the center and that is going to be surrounded by five chlorine atoms. And then we have to fill in our remaining electrons which chlorine will get six each to complete the architect. And then to show the dipole moments of this, we use the electro negativity trend. That electro negativity increases as you go up into the right of the periodic table. And so based on that chlorine is more electro negative than arsenic. And so that's why we're going to draw a dipole moments towards chlorine from arsenic. And so when we do that and we examine the geometry of this structure, we know that the geometry is tribunal by pure a middle. And so because of this, our die poles all cancel out. And when we have diet poles dot all canceled out. This gives us a non polar molecule. And so We know that we can we can now move on to answer choice to and the answer choice one is not going to be within our answer next we have floro methane. So with floral methane we have with floral methane we have one carbon. Carbon is a group for a element and therefore has four valence electrons. Hydrogen is a group one a electron and has one valence electron and there's three of them. So that's gonna give us three total. And then lastly we have a floor in here, Florida is a group seven a element and therefore has seven valence electrons. And when we add these up, it's going to give us 14 electrons total. So 14 electrons total to construct our figure. So what is this going to look like? Well we have methane and so that's going to be a carbon that's bonded by three hydrogen like So and then we have one flooring here, carbon likes to bond make four different bonds, hydrogen and florie likes to bond once just to complete their octet. And so we're going to draw the remaining electrons around florian giving it six to complete its octet. Once again following the electro negativity trends. Flooring is more electro negative than carbon. So we're gonna draw diet pool going upwards and carbon and hydrogen have such a very close electro negativity difference that we're not going to consider the dipole moments. So if we look at this geometry. This geometry is going to be tetra he'd rel so we're going to have a tetrahedron geometry. And if you look at the dyp holes, the dye poles actually don't cancel. So die poles don't cancel. And this is going to give us a polar molecule. So we will have an overall dipole moment with and her choice to So answer choice two is going to be within our answers. Just gonna highlight answer choice too. Moving on, we have answer choice three and that's going to be our selenium hex of chloride. The similar process is going to follow. Selenium is a group six a element and therefore has six valence electrons. Chlorine is a group seven. A element has seven valence electrons. However, there's six of them. So we have 42 electrons there Total. This is going to give us 48 electrons to construct our figure. We have one selenium that's bonded to a chlorine six different times. And as before chlorine is going to get six electrons total or around each one to complete its octet and to account for the other remaining electrons. And once we examine that we look at the electro negativity trends, chlorine is of course more electro negative than selenium. So we're going to draw dipole moments towards chlorine. And we noticed that the geometry of this molecule here is going to be Octa federal. And if you look at their di po moments, we see that the dyp holes all cancel the dyp holes end up canceling out. Sorry, end up canceling out. This is of course indicative of a non polar molecule. And so answer choice three will not be our answer. Moving to our last and final answer choice, we have sulfur fluoride or die fluoride. We have sulfur which is a group of six a element and has six valence electrons. And then we have flooring here which is a group seven a element that has seven valence electrons but there's two. So we have 14. And if we add this up, we're going to have a total of 20 electrons to construct our figure. Now when we draw this figure out, we're going to have our florins at an angle with our sulfur. We're gonna have our six electrons around floor and to complete the octet. And then we put the remaining two electrons on that sulfur. So sulfur can actually expand its octet because it's a group three or period three or below element. And so going to electronic activity trends, florian is more electro negative than sulfur. So we draw diet pills going that way and then we'll be examined our geometry. We say that our geometry for this shape is going to be bent and in a bent molecule, the dyp holes don't cancel out. And because they don't cancel out. We end up with a Diet paul moment overall and our molecule would be polar. So our answers are going to be answer choice to an answer choice for overall, I hope this helped, and until next time.